Band 32, Heft 1

Fire is considered one of the main risks leading to building collapse. Lightweight concrete comprises a variety of components, each of which has a distinct behavior under the effect of temperature change. A total of 16 concrete mixtures were investigated in this article. A reference mix of concrete comprising simply ordinary Portland cement and ten mixes having varying percentages of fine and coarse lightweight aggregates (pumice), which were replaced gravel and sand by fine pumice and coarse aggregates pumice by 20, 40, 60, 80, and 100%, respectively. In addition, the study focused on the effects of adding fibers to lightweight aggregate concrete mixtures. Polypropylene fibers, carbon fibers, and steel fibers were employed as fiber additions. The binary mixture had higher density than the remaining mixtures containing one substitute. The behavior of six concrete mixes in addition to the reference mix of ordinary concrete after exposure to temperatures 100, 250, 350 and 450°C for 2 h and then cooled in two ways (water and air) as well as examined directly and the results showed that the concrete mixes containing fiber had better behavior compared to other mixtures, especially at high temperature. If left to cool in the air, the lightweight concrete containing volcanic pumice can recover its compression strength after being exposed to high temperatures.

Buildings subjected to elevated temperatures or thermal shock can be exposed to many changes in their properties, such as phase transformation and weight loss; therefore, the thermomechanical stability of mortars is essential to maintain their properties. In this work, different ratios of partially stabilised nano-zirconium oxide (ZrO 2 ) were used as a partial replacement by weight of kaolin to prepare a refractory mortar. Five ratios (5, 7.5, 10, 12.5, and 15%) of ZrO 2 , as well as unfired kaolin, water, and internal lubricant (potassium silicate) were applied to increase the specimen’s cohesion. The results showed that ZrO 2 additives are suitable to be used for the production of refractory mortar as a result of increased physical and mechanical strength.

Thermosetting epoxy resin polymer with cycloaliphatic amines curing agent has been widely used for a composite matrix with carbon fiber reinforcement. The utilization was increased due to the superior performance of this epoxy resin compared to other polymers. However, a changing operational environment has potentially reduced composite performance, which most likely begins with matrix degradation. This research applies thermal treatment by the quenching process sequence to the epoxy resin matrix and its reinforced carbon fiber composite (CFRP). The composite is made by epoxy resin diglycidyl ether bisphenol-A, curing with cycloaliphatic amine as matrix and strengthening carbon fiber mat/woven. Three times quenching treatment was performed by heating the specimen around the glass transition temperature and then dipped immediately in fresh water. After quenching treatment, the epoxy resin shows a reduction in tensile strength and elongation. Under infrared observation, epoxy resin does not significantly show changes in functional groups. Investigation under X-ray refraction also indicates no difference in a crystalline structure; this epoxy resin stays in an amorphous form before and after quenching. In contrast to the matrix, the quenching treatment of the CFRP composite above the epoxy resin s glass transition temperature revealed an increase in the interlaminar shear strength (ILSS). The matrix ductility reduction after quenching should be carefully considered for application in the form of epoxy resin sheets or CFRP composite construction materials.

This research work is related to the use of environment friendly materials like fibers of coir, polypropylene and jute in concrete. An economical reinforced concrete is produced by reducing the diameter of steel bar by using fiber ropes. We have examined the compressive and flexural strength of fiber-reinforced concrete. In this study, concrete mix is prepared by using coir fibers. Although instead of using only conventional steel bars, reinforced concrete behavior was investigated with the combination of polypropylene fiber and jute fiber ropes along with steel bars for a constant water binder ratio. These fiber ropes are wound around steel bar with the help of Zepoxy 300 for proper bonding of fiber ropes and steel bar. The results demonstrate that properties of concrete are enhanced by using fibers. Fiber ropes with steel bar in coir concrete increased the flexural strength and compressive strength by 6 and 7%, respectively. Furthermore, it is observed that the addition of fibers in concrete changes the cracking pattern of reinforced concrete beams.

A number of destructive and non-destructive tests were conducted on rock samples collected from various zones in northern Iraq. So far, for Iraqi rocks, few studies have correlated Schmidt hammer rebound ( R ) with both unconfined compressive strength (UCS) and Brazilian tensile strength (BTS). In this study, the objective is to develop a relationship between the rebound number of Schmidt hammer surface hardness (rebound number) and both the BTS and the unconfined compressive strength (UCS) of different types of northern Iraqi rocks. The required relationship should be based on measured values of the UCS, BT, and Schmidt hammer hardness. To determine the relationship between R and both the UCS and BTS, 120 intact rock samples were prepared and tested using a uniaxial compressive test machine, a Brazilian test apparatus, and an L-type Schmidt hammer test (BTS). Three different types of rock samples (sandstone, claystone, and limestone) were collected from several locations in northern Iraq (Domeez, Baadra, and Zawita). For the three types of rocks, a new linear correlation with a high value of the regression coefficient R 2 is presented, linking the UCS and BTS separately versus R . For the three types of rocks studied, the correlation between UCS and R is better than the correlation between Brazilian tensile strength (BTS) and R .

In this study, the effects of calcined diatomaceous earth (CDE), polypropylene fiber (PF), and glass fiber (GF) on the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) were observed, and a total of 33 UHPFRC mixtures, consisting of 3 mixtures without fiber, 15 mixtures with PF, and 15 mixtures with GF were prepared. Subsequently, the fresh concrete mixtures were tested for flow, while the hardened concrete specimen’s mechanical properties were analyzed. These tests include compression, splitting tensile, and flexural tests. The test results showed that the use of 5 and 10% CDE as a binder for cement replacement improved the compressive strength, splitting tensile strength, and flexural strength of the UHPFRC. Furthermore, the addition of PF and GF contents of up to 1% of the concrete volume increased the compressive strength of the UHPFRC, while their contents of up to 1.5% improved their splitting tensile strength and flexural strength. It is also important to note that the workability of the UHPFRC reduced as the fiber and CDE contents increased. Finally, based on the experimental data tested in this study, the relationship between splitting tensile strength, flexural strength, and compressive strength of the UHPFRC containing PF and GF were proposed. Moreover, the reduction in flow value, which is a function of the volumetric content of both PF and GF, with the CDE contents was also proposed.

The need for wood in the ship building industry continues to grow every year. An alternative raw material is needed to replace wood at a more affordable price, namely, bamboo laminated boards. However, bamboo has a weak connection between its segments, with a maximum length between components of less than 40 cm. To reduce these weaknesses, the connection between bamboo segments with laminated boards is carried out as follows: scarf joint, butt joint, finger joint, desk joint, and tongue and groove joint. The study aims to determine the connection’s effect on each connection variation’s strength. Tensile tests and bending tests were carried out on the test specimens. The average results obtained were quite varied for the tensile test, which were in the range of 81.36–118.62 MPa, while the results of buckling test were in the range of 395.28–475.89 MPa. This study revealed that the connection of the specimen with seven layers had a value of 118.62 MPa in the tensile strength test and 475.89 MPa in the buckling strength test, while 3 layers finger joint samples with the lowest buckling tensile strength value had a value of 81.36 MPa tensile strength and 395.28 MPa bending strength.

Due to subgrade-related concerns, the performance of Indonesia’s ballasted track continues to be significant impediments for the Indonesian railway stakeholders’ intention to increase the speed of passenger train operations. This study aims to examine the vertical compressive stress in the subgrade of Indonesia’s ballasted track and two asphaltic rail track designs, asphaltic overlayment and asphaltic underlayment, under various cyclic loading conditions based on three different train speeds, 120 (low speed), 240 (medium speed), and 360 kph (high speed). The AC layer thicknesses for each asphaltic rail track design are as follows: 0.1, 0.2, 0.3, and 0.4 m for asphaltic underlayment, and 0.075, 0.15, 0.225, and 0.3 m for asphaltic overlayment. 2D finite element models and simulations were used to capture and predict the subgrade’s vertical compressive stress performance. The most obvious finding to emerge from this study is that the asphaltic overlayment track has a greater capacity for transmitting and decreasing stresses from the top structure to subgrade layer than the asphaltic underlayment track and the Indonesia’ ballasted track, respectively. This research can shed light on the prospective application of asphaltic rail track to the Indonesian rail network for the faster passenger trains operation.

In this work, the influence of using hybrid fibers on the mechanical properties of two types of concrete: high-strength concrete (HSC) and lightweight concrete (LWC) was studied. Using hybrid fibers instead of using only one type reduced the negative effect on concrete mechanical performance. The glass fiber (GF) and polypropylene fiber (PPF) were used in different contents ranged from 0.2 to 1% as weight % of binder content. Moreover, combinations of both fibers “GF + PPF” were used in contents % of “0.3 + 0.5%,” “0.5 + 0.5%,” “0.3 + 1%,” and “0.5 + 1%.” LWC mixes were prepared by replacing 40% of the coarse aggregate of reference mix with volcanic material (pumice) as a volumetric replacing. To produce HSC, the water-to-cement ratio was reduced to 0.3, 10% silica fume was added, and 1% super plasticizer was used to obtain the consistency. Compressive strength, splitting strength, and flexural strength tests were carried out. The results showed that using 0.7% GF displayed the highest increases in compressive, splitting tensile, and flexural strength of HSC and LWC mixes. Furthermore, GF exhibited better performance and higher values in compressive, splitting tensile, and flexural strength tests in comparison with PPF. The optimum hybrid fiber content displaying the highest increment of all tested properties in both concrete types, HSC and LWC, was “0.5% GF + 0.5% PPF.”

This article aims to simulate the behavior of reinforced concrete (RC) tapered columns subjected to static loads. The experimental data used in the study are from the literature. Two of the simulated columns are slender columns tested under uniaxial eccentric loads. The third one is a short column and was tested concentrically. The concrete damaged plasticity (CDP) model offered in the Abaqus software, which accounts for stiffness degradation of concrete in both compression and tension, was used. The modulus of rupture of concrete and the value of the cracking strain proposed by the Abaqus analysis user’s manual were used as the parameters of tension stiffening. The modified Hognestadʼs model was used for the compressive behavior of concrete. The Static Riks analyses were performed with an activated geometric nonlinearity. The numerical failure load is 100.125, 99.297, and 102.16% of the experimental failure load for Models 1, 2, and 3, respectively. The agreement of the numerical results with the experimental results has confirmed the efficiency of the CDP model to simulate the concrete behavior, and has also revealed the validity of the numerical models.

Calcined diatomaceous earth (CDE) with a maximum grain size of 143 μm was used to partially replace 5 and 10% of cement in ultra-high-performance concrete (UHPC) mixtures. The other materials used in producing the concrete include Ordinary Portland Cement, iron ore powder, and river sand with maximum grain sizes 112.5, 231, and 766.2 μm, respectively. Moreover, the UHPC specimens designed with a water–cement ratio of 0.2 and a superplasticizer of 1.5% from the cement weight were tested for flow, compressive strength, flexural strength, splitting tensile strength, durability against NaCl and Na 2 SO 4 attack, and resistance to 400, 500, and 600°C temperatures. The results showed that the use of 5 and 10% CDE to replace cement was able to increase the compressive strength, flexural strength, splitting tensile strength, the durability of UHPC against NaCl, and Na 2 SO 4 , as well as its resistance to high temperatures but reduced the mixture flow.

The current study aims to evaluate the rutting resistance of warm miox asphalt (WMA) taking into consideration the influence of production temperature. Rediset WMX, Sasobit, and Rediset LQ were used to manufacture WMAs. WMA was manufactured at 125°C (for a modified soft binder, 100/150) and 135 and 145°C (for a modified hard binder, 40/60), while the control hot mix asphalt (HMA) was manufactured at 145 and 155°C for soft and hard binder, respectively. Although WMAs manufactured using hard binder (40/60) were successfully produced at a temperature 20°C lower than that for the control HMA, its rutting performance was inferior to that of the control HMA with both Rediset LQ and Rediset WMX; while the rutting performance of the Sasobit-modified hard binder–asphalt mixture was equal to that of HMA because Sasobit increases the stiffness of binder. On the other hand, all WMAs produced at a temperature of 145°C performed better than or equal to HMA. In summary, binder grade has an important role in the dosage of additive, performance, and the reduction of the manufacturing temperature of WMA; on the other hand, WMA additives delay the degradation of rutting rate for mixes, the results also showed that WMAs have an equal performance to or better performance than that of conventional HMA.

The main objective of this study was to analyze the microstructural characteristics and strength performance of dissimilar AISI 431 steel/AISI 1018 steel joints developed using rotary friction welding. The microstructural characteristics of different regions of dissimilar rod-to-plate joints were analyzed using optical microscopy. The tensile properties and microhardness of dissimilar rod-to-plate joints were evaluated to assess the joint performance. The microhardness distribution across the cross-sectional region of dissimilar rod-to-plate joints was recorded and correlated with the tensile failure. Scanning electron microscopy was used to analyze the fractured region of dissimilar rod-to-plate tensile specimens. Results showed that the dissimilar AISI 431 steel/AISI 1018 steel joints steel exhibited a tensile strength of 650 MPa, a yield strength of 452 MPa, and a % elongation of 18%. The microhardness of the weld interface (WI) was higher up to 515 HV 0.5 . The grain growth and resulting lower hardness in heat-affected zone (HAZ) are mainly responsible for the failure of the joints in HAZ only. The superior tensile properties and greater interface hardness of dissimilar AISI 431 steel/AISI 1018 steel joints are correlated with the evolution of finer grain microstructure in the WI zone.

In this study, the wear performance of boron carbide (B 4 C) and graphene (Gr) particles reinforced Al–Cu alloy composites was investigated. The composite samples were made using the solid-state manufacturing process. The wear performance was assessed using a pin-on-disc tribometer. The Taguchi optimization approach was used to determine the performance of each parameter. All experiments were carried out using the L27 array, which included three sets of parameters such as applied load, disc speed, and reinforcement percentage. The ANOVA approach was used to examine the impact of each parameter. According to the findings, the weight on the pin has the greatest influence on wear, followed by sliding speed and reinforcing percentage. The addition of B 4 C particles improves the wear resistance, and the Gr functions as a self-lubricating agent while in use. Scanning electron microscope analysis of worn-out samples revealed an abrasive type of wear process.

The present study describes the peristaltic flow of Jeffrey fluid with nanomaterial bounded under peristaltic waves in a curved channel. Silver (Ag) is the nanomaterial used for this purpose, and base fluid is water. The diversity of peristaltic waves is captured under four different wave profiles traveling along the curved channel. The consequences of heat generation and mass concentration are also taken. The problem is modeled under physical laws and then simplified using the lubrication technique. The obtained system is sketched in graphs directly using a numerical scheme. The physical outcomes of involved parameters on axial velocity, temperature variation, concentration profile, and streamline patterns are discussed in the last section.

The use of thin film-coated micro-tool electrode introduced a new technical solution to bring the best technical–economic efficiency in the field of non-conventional machining processes. Multi-objective optimization of process parameters in micro-electrical discharge machining (EDM) is very limited with the help of thin film-coated micro-tool, which brought benefits for the industry. In this research work, the technological parameters such as voltage ( V ), spindle rotation, and capacitance ( C ) in micro-EDM using carbon-coated electrode were optimized, and Z -coordinate depth of cut and tool wear rate were selected as response variables. Taguchi is combined with Deng’s method to solve this multi-objective decision problem. The results showed that Taguchi–Deng’s method is the right solution for multi-target decision in micro-EDM using the coated electrode. C is the strongest influence on optimal efficiency, and it is the smallest with V . The machining quality under optimal conditions is improved.

Due to their excellent thermal conductivity, lightweight, and ease of processing, aluminum alloys are the material of choice for piston manufacture in internal combustion engines. Nanoparticles (NPs) of alumina (Al 2 O 3 ) with a size of 25 nm were incorporated into an aluminum piston alloy to examine the effect of the NP addition on wear resistance and fatigue behavior. The stir casting method has been utilized to manufacture experimental samples of the composite material by altering the particle weight ratio of aluminum to the matrix alloy to 2, 4, and 6 wt%. The surface morphology of the samples has been examined using an electronic scanning microscope. The results of the wear and fatigue tests indicate that the addition of Al 2 O 3 to the composite enhanced its fatigue resistance and wear strength, with the exception of 6 wt% weight ratio. The best improvement in wear resistance and fatigue strength occurs at 4 wt% Al 2 O 3 particles, which are 12.13 and 67.5%, respectively, more significant than the pure metal and other composites. The mechanical properties of the alloy samples have been enhanced by adding Al 2 O 3 NPs of 25 nm size into the piston’s aluminum matrix alloy. Stir casting was employed to produce the needed composites by incorporating Al 2 O 3 NPs at varied weight percentage ratios of 0, 2, 4, and 6 wt% into the master alloy. Before the composite alloy reached 6 wt%, including Al 2 O 3 NPs, the alloy’s hardness and tensile strength improved, according to the experiment results.

Fiber accumulation due to printing ink inconsistency makes additive manufacturing (AM) of reinforced thermoset syntactic foam composites difficult. This study predicts and analyzes the mechanical properties of AM-made carbon fiber-reinforced syntactic thermoset composites to overcome experimental limitations. Thus, an adaptive neuro-fuzzy inference system (ANFIS)-based model creates an accurate mechanical behavior prediction under a variety of conditions without experimental inquiry. Compression and flexure tests assessed the ANFIS model’s validation. The model’s predictions were very close to reality, validating the approach taken to improve the technical assessment of the created composites, which are perfect for weight reduction, mechanical improvement, and product complexity.

Purpose This article aims to investigate the structural behavior of beam–column joints subjected to axial force. The geometry used is the addition of a number of beam connections to the column, and the differences in the numbers of beams used are 1, 2, 4, and 4, denoted as V1, V2, V3, and V4, respectively. Design/methodology/approach In this work, the analysis was performed using the numerical finite element method with ABAQUS software. A benchmarking analysis was also conducted to validate the numerical results. Findings Several numerical simulations showed that of the variations tested, the V2 model demonstrated the highest force value among the four test models, at 130.883 kN. The displacement caused by the force was 227.32 mm, which was the lowest value among the four test models. On the other hand, the V3 model received the smallest force value among the four test models, at 24.576 kN, with a displacement of 227.49 mm. The displacement value was greater than that for the V2 model, further indicating that the V2 model was the stiffest of the four models tested. Originality/value This study shows that the influence of beam–column joint geometry is not limited to double-extended end-plate bolted connections.

Since the cost of electrodes in electrical discharge machining (EDM) is usually too high, it leads to a significant increase in the production cost. Hence, it is important to conduct research aimed at reducing the manufacturing cost of electrodes. Currently, coated electrodes are a new process solution in EDM. It can improve the economic and technical efficiency of this technology. In this article, the efficiency of the graphene-coated aluminum (Al) electrode in the EDM for Ti–6Al–4V was analyzed and evaluated. Material removal rate and tool wear rate were used as quality indicators in this work. The research results have shown a significant improvement in quality characteristics in EDM with coated electrodes compared to EDM with uncoated electrodes. The surface quality of the specimen with coated electrodes in EDM was also improved.

A novel low-cost polyurethane (PU) elastomeric material reinforced with mat-form fiberglass for alternative ship material was developed. The hand lay-up technique was used to prepare samples with glass fiber contents of 0, 7, 9, 11, and 15% by weight. Several tests, including density, tensile, and hardness tests, have been conducted to investigate the effect of fiber content on the material properties of the developed materials. The test results found that only composites with 0% (PU) and 7% (PFg-7) fiberglass had met all Lloyd’s Register criteria. PFg-7 has a density of 1,098 kg/m 3 , a hardness of 66.15 shore-D, a tensile strength of 21.32 MPa, and an elongation at break of 47.06%, a higher hardness, elastic modulus, and yield strength than PU. PFg-15 achieved the highest density, hardness, tensile strength, elastic modulus, and yield strength, which were 1,228 kg/m 3 , 68.85 shore-D, 32.13, 2,176, and 30.89 MPa, respectively. The elastic modulus and yield strength of PFg-15 were 5.6 times and 3 times higher than those of PU but PFg-15 did not meet the elongation at break criteria. PFg-9, PFg-11, and PFg-15 showed brittle properties, as indicated by relatively high hardness, elastic modulus, and yield strength compared to the results from various references.

Evaluating the subground properties during the initial stage of a construction of building is important in order to estimate the suitability of soil quality to the technical requirements of bearing capacity, resistance to stress, and strength. This study presented the evaluation of the geotechnical properties of soil intended for the construction of Max IV facility of Lund University, performed in fieldwork and laboratory. The in situ methods included drilling boreholes, core sampling and assessment, crosshole measurements, and borehole logging. The laboratory-based measurements were performed at Swedish Geotechnical Institute and combined seismic measurements of drill cores, determination of the uniaxial compressive strength (UCS), and examination of material property: sieve analysis and natural moisture content. UCS was evaluated with regard to velocities of elastic P-waves. The synchronous light test by X-ray diffraction was performed for qualitative analysis of mineral composition of samples. The study applied integrated approach of the diverse geophysical methods to solve practical tasks on the evaluation of foundation strength and geotechnical parameters. This study demonstrated the benefits of integrated seismic and geophysical methods applied to soil exploration in civil engineering for testing quality of foundation materials.

Blood flow in narrow channels such as veins and arteries is the major topic of interest here. The Casson fluid with its shear-thinning attribute serves as the blood model. Owing to the arterial walls, the channel is configured curved in shape. The activation energy and nonlinear thermal radiation aspects are highlighted. The channel boundaries are flexible with peristaltic wave travelling along the channel. The mathematical description of the problem is developed under physical laws and then simplified using the lubrication technique. The obtained system is then sketched in graphs directly using the numerical scheme NDSolve in Mathematica software. The physical interpretation of parameters on axial velocity, temperature profile, concentration, and streamline pattern is discussed in the last section.

The photovoltaic sector needs a high-throughput slicing method that produces minimal waste to meet rising demand. Wire electric discharge machining (WEDM) has emerged as an alternative slicing method in recent research efforts. Polycrystalline silicon is sliced using the WEDM process with a zinc-coated electrode of Ø0.25 mm in diameter. Experiments were planned and conducted according to Box Behnken’s design of experiments. As inputs, seven different process parameters were used: pulse on time (PONT), pulse off time (POFFT), peak current (PC), spark gap voltage (SGV), wire feed (WF), wire tension (WT), and water pressure (WP). Response parameters measured were cutting speed (CS), surface roughness (SR), and kerf width (KW). Various process parameters have also been analyzed with ANOVA methods for predictive modeling. Based on experimental data, this study determines the appropriate optimal solutions via desirability functions. During the WEDM process, the PONT, POFFT, PC, and SGV significantly influence the discharge energy on the sliced surface. As a result of this study, CS of 0.78 mm 2 /min, SR of 2.87 μm, and KW of 0.70 mm were observed at the optimal settings of PONT of 119 μs, POFFT of 42 μs, PC of 38A, SGV of 36V, WF of 3 mm/min, WT of 2 kg and WP of 6 kg/cm 2 . Surface morphology was determined using scanning electron microscope and Energy dispersive X-ray to investigate the surface characteristics.

The high-temperature corrosion of turbine blades poses a serious threat to the efficiency of electrical gas power stations, which results in heavy economic losses. In the present study, the Inconel 738 low-carbon steel utilized in the turbine blades was coated on alumina (Al 2 O 3 ) in a variety of percentages of carbon nanotubes (4, 6, and 8 wt%) using the plasma spray technique. The behavior of the Inconel 738LC alloy with and without artificial ash (67 wt% H 2 SO 4 and 33 wt% V 2 O 5 ) at different temperatures (650, 750, 850, and 950°C) was investigated. The cycles of hot corrosion and oxidation were achieved in an electric furnace for 10 cycles of 5 h each. After each cycle, the weight changes were measured and recorded. The SEM and XRD achieved for all the specimens were noted, before and post the corrosion.

The focus of this work is to study the influence of flexoelectric phenomenon on the electromechanical response of graphene-reinforced nanocomposite (GNC) nanorods. An analytical model has been derived by utilizing the Timoshenko beam theory and the principle of variational work by incorporating flexoelectric effects. The GNC nanorod is subjected to a concentrated load acting downward for clamped-free and simply supported support types. The GNC is reinforced with a defective graphene sheet as it is known to show enhanced polarization. The elastic properties of defective graphene sheets have been evaluated using molecular dynamic simulations. The outcome of our model shows that the flexoelectric effect must be considered for accurate modeling of nanostructures. Irrespective of the support type, flexoelectric effect improves the stiffness of the nanorod. We also observed that the stiffness of the nanorod is significantly influenced by the support type. This work presents an opportunity for the development of high-performance graphene-based nanoactuators/sensors.

Various process nonhomogeneities in the cold rolling lead to an uneven distribution of deformation across the strip cross-section, resulting in the induction of residual stresses. This study investigates the longitudinal residual stresses in cold-rolled EN AW-5083 aluminum alloy strips using the finite element method (FEM) to achieve reliable predictions. The impacts of process parameters, including the reduction ratio, coefficient of contact friction, and front and back tensions, were analyzed. Changes in residual stresses, depending on the process parameters, were determined by the distribution of linear and shear strains, as well as the strain hardening conditions at the exit part of the deformation zone. An increase in the reduction ratio from 20 to 50%, as well as an increase in the friction coefficient from 0.1 to 0.2, resulted in decreased stress values. The residual stresses on the strip surface, determined by the experimental deflection method, were consistent with the results obtained by FEM simulation. Under the impact of back and/or front tensions, there is a reduction in longitudinal residual stresses, with the front tension exerting the greatest influence. The research results show that the FEM is a reliable tool for predicting residual stresses in cold-rolled strips.

Ocean thermal energy conversion (OTEC) is a floating platform that generates electricity from seawater heat. The cold water pipe (CWP) used in OTEC has a length of 1,000 m and a diameter of 10 m, making it susceptible to bending loads from ocean currents. To find suitable geometry and material for the CWP, the finite element method was used to model the real-world geometry. In the D / t variation, lower ratios (increased thickness) result in higher critical moments, maximum stress, strain, and displacement. D / t 50 was chosen for the CWP. In the L / D variation, the critical moment’s impact on L / D ratio was minimal, while reducing L / D (shorter pipe) increased strain, and larger L / D geometries had higher displacements. L / D 10 was selected as it balanced critical moments and reduced the number of stiffeners needed. For diameter size variation, larger diameters increased critical moment and strain, but smaller diameters (larger L / D ratios) also showed high strain due to necking at two points. A diameter of 12 m was chosen for its exceptionally high critical moment. Steel was selected as the suitable material due to its higher critical moment and maximum stress, despite its higher weight and lower maximum strain than composites. Capital shape imperfections had a minimal effect on the CWP’s structure as they were localized.

This work demonstrates deformation in hygrothermoelastic medium with an overlying non-viscous fluid of uniform thickness. A constant mechanical force is applied along the fluid-layer. The normal-mode analysis technique is applied to solve the governing equations of the medium. The analytical expressions of displacement, moisture concentration, temperature distribution, and stresses are obtained for the hygrothermoelastic medium and depicted graphically for different values of fluid-layer depth. The finding of this work is that the values of the aforementioned physical quantities decrease with an increase in the fluid-layer, which justifies the decaying nature of waves with depth. The novelty of the problem is that no research has been carried out so far for analyzing hygrothermoelastic medium subjected to thermoelastic deformation.

Recently, Cu–Au core–shell nanowires have been extensively used as conductors, nanocatalysts, and aerospace instruments due to their excellent thermal and electrical conductivity. In experimental studies, various methods have been presented for producing, characterizing, and strengthening these structures. However, the mechanical behavior and plastic deformation mechanisms of these materials have not been investigated at the atomic scale. Consequently, in the present study, we carried out uniaxial tensile tests on Cu–Au nanowires at various tension rates and temperatures by means of the molecular dynamics approach. The Cu–Au interface was found to be the main site for nucleation of perfect dislocations, Shockley partials, and stacking faults due to the stress concentration and high potential energy arising from the atomic mismatch between shell and core layers. It was observed that an increase in the strain rate from 108 to 1,011 s −1 shortened the time required for the nucleation of dislocations, decreasing the dislocation density. This emphasizes that dislocation nucleation and slip mechanisms are time-dependent. Moreover, it was found that the interaction of Shockley partials can lead to the creation of lock dislocations, such as Hirth, Frank, and Stair-rod dislocations, imposing obstacles for the slip of other dislocations. However, as the tension temperature rose from 300 to 600 K, opposite-sign dislocations removed each other due to thermally activated mechanisms such as dislocation climb and dislocation recovery. Furthermore, the combination of Shockley partial dislocations decreased the stacking fault density, facilitating the plastic deformation of these structures. The yield strength and elastic modulus of the samples increased with the strain rate and substantially decreased as the temperature rose.

As aggregate material typically comprises 65–75% of concrete volume and has a significant effect on its mechanical properties, aggregate type considerably affects concrete behavior at high temperatures. In this study, 80 concrete cylinders and 60 cubes were cast to investigate the residual strength of normal concrete that contains lightweight expanded clay aggregate (LECA) with different volumetric replacement ratios (0, 10, 20, and 30%) of the coarse aggregate. After the fire flame exposure effect of steady-state temperatures (300, 400, 500, and 600°C), and a sudden cooling process, the mechanical tests (compressive strength, tensile strength, and modulus of elasticity; Ec), as well as mass loss and thermal conductivity, were carried out on the specimens. The results indicate that increasing the LECA content in the mixture leads to better strength retention after exposure to fire. After exposure to a steady-state temperature of 600°C, the amount of decrease in mass, residual compressive and tensile strengths, and the residual amount of Ec were 7.61, 7.5, 7.16, and 6.24%; 57.1, 66.8, 69.8, and 72.0%; 22.4, 32.7, 41.8, and 48.6%;, and 16.0, 22.3, 23.4, and 24.3%, respectively, for the considered volumetric replacement ratios of 0, 10, 20, and 30%. Also, the values of the thermal conductivity were 1.4889, 1.1667, 1.0912, and 1.0410 W/m K, respectively.

Cement has shaped the modern built environment, but its production generates substantial carbon dioxide emissions. Consequently, there is an urgent need to identify alternative cementitious building materials for sustainable construction. In this study, cement mortars (CMs) were produced by partially replacing cement with nanoclay (NC) and granite dust (GD). The replacement proportions (% by weight of cement) of these materials were 1.5, 3, and 4.5% for NC and 10, 20, and 30% for GD. For mortars containing NC but not GD, the strength was maximized when the NC replacement proportion was 3%. To evaluate the combined effect of partially replacing cement with both NC and GD on the fresh and hardening properties of cement-blended mortars, ternary binder mixtures containing 3% NC together with 10, 20, or 30% GD were prepared, and their workability, bulk density, compressive strength (at 7, 28, and 90 days), and flexural strength were measured. Increasing the content of NC and/or GD reduced the flowability of these mortars relative to that of the reference mortar mix because it increased the content of fine materials. CM containing 3% NC and 10% GD had the highest compressive strength at 7, 28, and 90 days while also having the greatest flexural strength when compared to the control mix. This is most likely due to the high silica and alumina content of NC and GD, as well as their high specific surface area, which would improve the maturity and density of the matrix when compared to cement alone.

Shear wall structure is one of the options as an appropriate lateral load-bearing system for new structures or as a means of retrofitting existing buildings. There are many types of shear walls, including steel plate shear walls (SPSWs). In enhancing its function, a thin SPSW is added with a stiffener. However, steel shear walls with stiffeners increase construction costs due to the time-consuming factor and the high cost of welding thin plates. Therefore, the infill shape was modified to increase the energy dissipation capacity of the SPSW. This study conducted simulations by varying the geometry, mesh, load factor, and materials used in SPSW. The specimen was modeled and tested using the ABAQUS application’s finite element analysis. The simulation was done by ignoring welded joints, fish plates, and bolts. The result that was the output of the simulation was hysteresis behavior. In addition, the contours that occurred were also observed in this study. The H1 shape had the best hysteresis force–displacement graphics among the nine other geometric shapes. Ten mesh sizes were tested, starting from 25 mm and increasing by multiples of 10 up to 115 mm. The results showed significant differences, with a 33.3% increase at the 115 mm size, which was considered irrational. The load factor represented the applied load in each substep, and a load factor of 2 means the load was doubled compared to a load factor of 1. Seven materials were tested, and high carbon steel outperformed others as it can handle loads up to 1,000 kN, demonstrating excellent energy dissipation capabilities. Graphical abstract

This research investigated the largest magnitude of displacement and horizontal tensile strain in several critical locations within the asphalt concrete (AC) layer in both the flexible pavement highway (FPH) and asphaltic overlayment track (AOT) structure using the numerical modeling method. The role of the hauling loads, speed, and loading cycles of freight truck’s dumps and freight train’s wagons on the mechanical behavior of FPH and AOT in terms of the permanent deformation and fatigue cracking was examined. Furthermore, the performance of the FPH and AOT in terms of permanent deformation and fatigue cracking characteristics due to various magnitudes of hauling loads, speed, and loading cycles of freight truck’s dumps and freight train’s wagons was compared to determine the optimum infrastructure for the freight coal transportation, based on the hauling capacity as well as the magnitude of permanent deformation and the horizontal tensile strain of the AC layer. According to the findings of this study, it is suggested to choose the AOT structure with fourth or sixth loading systems to run the freight coal transportation with the highest magnitude of the hauling capacity of 360,000 tons, since it produces the minimum magnitude of the permanent deformation and fatigue cracking of the AC layer. Future research should be conducted to examine the potential and the characteristics of fatigue cracking due to the contact between the edge of the sleeper and the surface of the AC layer in AOT.

In numerous engineering applications, metal matrix composites strengthened by ceramic particles have played an important role. For this purpose, an aluminum (Al 7075) nanocomposite has been fabricated, and nano-zirconium oxide of particle size 40 nm (0, 0.8, 1.6, and 2.4) wt% reinforced Al 7075 alloy was produced using a stir-casting process. The effect of ZrO 2 NPs loading on mechanical properties along with the detailed characterization were demonstrated. The performance of Al with ZrO 2 nanocomposite was investigated by Vickers hardness tester, scanning electron microscopy, energy-dispersive X-ray, compression test, Lee’s disc, and Shore D instruments were utilized to determine the hardness, structural morphology, composition of the elements, Young’s modulus, thermal conductivity, and roughness values of the samples, respectively. The hardness (120.3–177) HV, compression strength (624.2–878.6) MPa, yield modulus (38–70) MPa, surface roughness (0.876–0.606) µm, thermal conductivity (2.0–2.39) W/m 2  °C improved by increasing the wt% of ZrO 2 NP reinforcement particles. The implication of these findings shows that 5 wt% nano-ZrO 2 -reinforced Al 7075 composites yielded better performance than pure Al 7075 alloy. To sum up, this investigation demonstrated that the ZrO 2 reinforcement enhanced the mechanical properties of Al 7075.

Titanium alloys are broadly used in the medical and aerospace sectors. However, they are categorized within the hard-to-machine alloys ascribed to their higher chemical reactivity and lower thermal conductivity. This aim of this research was to study the impact of the dry-end-milling process with an uncoated tool on the produced surface roughness of Ti6Al4V alloy. This research aims to study the impact of the dry-end milling process with an uncoated tool on the produced surface roughness of Ti6Al4V alloy. Also, it seeks to develop a new hybrid neural model based on the training back propagation neural network (BPNN) with swarm optimization-gravitation search hybrid algorithms (PSO-GSA). Full-factorial design of the experiment with L27 orthogonal array was applied, and three end-milling parameters (cutting speed, feed rate, and axial depth of cut) with three levels were selected (50, 77.5, and 105 m/min; 0.1, 0.15, and 0.2 mm/tooth; and 1, 1.5, and 2 mm) and investigated to show their influence on the obtained surface roughness. The results revealed that the surface roughness is significantly affected by the feed rate followed by the axial depth. A 0.49 µm was produced as a minimum surface roughness at the optimized parameters of 105 m/min, 0.1 mm/tooth, and 1 mm. On the other hand, a neural network having a single hidden layer with 1–20 hidden neurons, 3 input neurons, and 1 output neuron was trained with both PSO and PSO–GSA algorithms. The hybrid BPNN–PSO–GSA model showed its superiority over the BPNN–PSO model in terms of the minimum mean square error (MSE) that was calculated during the testing stage. The best BPNN–PSO–GSA hybrid model was the 3–18–1 structure, which reached the best testing MSE of 3.8 × 10 −11 against 2.42 × 10 −5 of the 3–8–1 BPNN–PSO hybrid model.

Glasses constructed, (1 − x ) (0.6595P 2 O 5 –0.0958ZnO–0.2447PbO) ·  x Sm 2 O 3 with x = 0.00, 0.0045, 0.0089, 0.0132, and 0.0261 mol%, had been created to investigate the attenuation of longitudinal ultrasonic waves at 2, 4, 6, and 14 MHz frequencies between 120 and 300 K. At a variety of temperatures, clear peaks of a large absorption curve have been seen. These peaks are dependent on the structure of the glass as well as the switching frequency. Maximum peaks have been shown to shift to higher temperatures, and the increase in overall frequency points to the presence of some kind of relaxation process. A thermally induced relaxation process is responsible for producing a calm approach, which has been identified as a result of this mechanism. A quiet approach has been defined as a consequence of a thermally triggered relaxation mechanism. The variance of the mean energy of activation of the mechanism counts on primarily the amount of Sm 2 O 3 mol%. Such dependency has been evaluated based on the loss of normal linear solid form, attaining low dispersion, and a large allocation of Arrhenius kind relaxation through temperature-autonomous relaxation power. The measured acoustical energy of activation values have been quantifiably represented based on the number of loss centers (amount of oxygen atoms that now move at a double-well potential).

Making environmentally friendly, long-lasting roller compacted concrete (RCC) was the primary focus of the laboratory experiments using disposed waste material (demolished buildings) and lowering the amount of fine aggregate adopting the ACI 327. The best way to dispose waste materials of demolished buildings such as ceramic tiles, clay bricks, and thermostone hollow blocks without using a sanitary landfill was to collect them, crush them with a crushing machine, and grade them by sieving to a fine aggregate. Reference mixture (RM) and six other environmentally friendly, long-lasting RCC mixtures were produced with partial fine aggregate volume replacements of 10 and 20% waste material. Following the production of the mixtures, the strength (compressive, splitting tensile, and flexural), porosity, absorption of water, and dry density were all tested. The results in accordance with the study’s conclusions are the RCC containing (20%) by ceramic tiles as fine aggregate increases RCC’s durability up to (5.76%) (2.96%) (2.83%) of strength (compressive, splitting tensile and flexural) at 28 days of testing, in opposition to the typical blend, then the blend that includes (10%) of ceramic tiles as fine aggregate with % growth up to (3.39%) (1.64%) (1.42%). While the clay bricks with 10% can be adopted, the results were slightly lower than the RM but still in the specification range (minimum recommendation of ACI 327 = 28 MPa). For the mixtures with 10 and 20% thermostone blocks fine aggregate, the results showed reduction in strength compared to the RM.

The utilization of eggshell (ES) waste as a composite filler has increased significantly in the last 5 years. This increase in usage took place due to its unique characteristics, which improve the properties of the resulting composite. Adding a weight fraction of ES particles into a composite can improve its mechanical properties, although not all studies have shown this phenomenon. Studies on these composites’ thermal and tribological properties are still limited, so more in-depth studies could be carried out. The degradation of composite performance due to friction or exposure to humidity and hot temperature is another area that is worthy of further study. In this work, we discuss changes in composites’ mechanical, thermal, and tribological properties associated with the addition of ES particles, examining both untreated particles and those treated with carbonation. This work can serve as a guide for the utilization of ES particles as an environmentally friendly composite material.

The main objective of this review is to study the effect of post-processing treatments on the mechanical performance of cold sprayed coatings. The cold spray (CS) process is an evolving technology for the rapid production of coatings at almost low temperatures, creating a thin, dense layer of coatings and a massive level of the additive manufacturing process with low-phase transition and less oxidization. In this process, powder particles are quickened by a process gas to supersonic velocity and impinge on the substrate, thereby establishing a higher adhesive bond between the substrate and the plastically deformed condition and eventually producing a deposition with the texture of the layer. However, the cohesive behaviour and metallurgical bonding is lower because of the lowest atomic diffusion among various splats of CS process with defects like pores, voids, and micro-cracks in the coating surface. It affects the properties of coating. In order to enhance the surface properties of coating, post-treatments are required. Heat treatment, friction stir processing, laser remelting, and shot peening are advanced treatments used to improve the performance of CS coatings. As a result, the mechanical, tribological, and electrochemical properties of post-treated samples are improved compared to coated samples.

This article presents an overview of the research on the effects of internal curing (IC) on ultra-high-performance concrete (UHPC). The process of adding a curing ingredient to the concrete mixture to serve as a water reservoir is known as internal curing. IC is a viable technique for supplying additional water for curing cement-based material with lower water-to-binder concrete. It is distinct from externally applied curing. The water meant for internal water curing is dispersed within the concrete after it hardened and facilitated the hydration process. It was used to minimize self-desiccation and shrinkage in UHPC. Based on the reviewed literature, an exchange between mechanical characteristics and autogenous shrinkage for concrete was observed for internally cured UHPC. Even though IC affects the mechanical characteristics, after 28 days, it was possible to achieve a compressive strength of over 150 MPa. Thermal curing was found to exhibit a remarkable effect on the development of UHPC strength. Experimental findings revealed that using pre-saturated aggregates for IC improves the tensile strength of UHPC. The scanning electron microscope images revealed that the bulk of the voids within the super-absorbent polymer cavities are filled with portlandite.

Skirted footings are used to increase the final carrying capacity of shallow foundations resting on unstable soil and to decrease settling by limiting the soil beneath them. Skirted footings are utilized as an alternative to pile driving in poor strength soils at the top layer, such as gypseous soil, to save project costs and time spent installing piles while maintaining excellent performance. The settling of circular skirted footings resting on gypseous soil subjected to loading, infiltration, and collapsing stages was investigated using numerical calculations in this research study to determine their stability under environmental loadings. Finite element analyses were carried out using the commercially available software GEO-STUDIO. The stage of gypseous soil and variable skirt depth to footing diameter ratios ( d / D ) were taken into consideration. The findings reveal that both the soil stage and the skirt embedment ratio have a substantial impact on the ultimate bearing capacity and the settlement of weak soil, with the skirt embedment ratio increasing resulting in superior skirted footing performance. Furthermore, the improvement in settlement for the loading stage is the smallest, whereas the value for the collapsing soil stage is the largest.

Improvements in mechanical characteristics of soils treated by nano-materials (NMs) have been proved in the last three decades. The improvements are mainly attributed to changes in the soil fabric where a noticeable rise in shear strength has been obtained. This work, therefore, addressed a numerical study on the influence of the soil fabric changes due to the NMs enhancement on a slope stability problem using an upper bound discretization scheme. A parametric study was carried out at seven different inclination angles from 15 to 45° and with a variety of combinations of angle of shearing resistance ( ϕ ) and cohesion ( c ) values. This was carried out for two different types of slopes on purely frictional materials and c – ϕ materials. A noticeable increase in stability was obtained, based on a set of re-generated design charts, due to NMs enhancement (attributed to soil fabric changes). The re-generated design charts did not require iterative procedures and extended both x and y boundaries when compared with other available charts in the literature. Examination of the influence of the NM on the failure modes, to provide an insight into different failure mechanisms due to the soil fabric changes, was also considered.

Collapsible soils are almost found in unsaturated states and involved significant engineering problems. Geotechnical challenges of such soils are represented by the hydro-mechanical behaviour during wetting–drying cycles due to the humidity and climate conditions. The main objective of this paper is to investigate the soil–water characteristic curve (SWCC) of unsaturated collapsible soils. In this study, three types of collapsible soils were investigated such as natural soils of sandy gypseous, silty loess, and artificial soil of gypsum–sand mixture. Determination of soil–water characteristic curve represented by wetting and drying paths has been done using a combination of the axis-translation technique ( i.e . pressure plate device) and vapour equilibrium technique ( i.e . salts solution desiccators) to cover a wide range of applied suction. The test results show that the air-entry value for all soils occurs at a very low suction range. At the boundary effect zone, the coarse grain size of the soil mass cannot hold the water molecules in the pore space, even with a low value of imposed suction. Moreover, the amount of hysteresis varied based on the geological formation and homogeneity of the soil fabric. Furthermore, SWCC has been interpreted by insignificant volume change and a slight reduction in void ratio, especially at high applied suction.

Sand raining is among the popular techniques used in the laboratory for preparing sand samples. Factors like the deposition intensity (DI) and the falling height (HF) affect the produced relative density (RD) in this technique. Studies showed that the RD increase as the HF increases. This is, however, applicable up to a critical HF beyond which the RD seems unaffected. According to previous experiments, the maximum RD achieved using the sand raining is about (70 ± 5)%. The preparation of samples with higher RD is a prerequisite required in many experimental models. In the present article, a new raining system, which is capable to prepare sand samples with a very high RD and with a fast sand flow, is introduced. The new system was used to examine the relationship between the HF and the RD under different trapped air pressures and using rain nozzles with three different opening diameters. The new system was found appropriate for reconstituting SP-SM with very dense specimens (RD > 99%) with achieving higher DI values and a reduction in preparation time of more than 90% in comparison to the classic raining technique. It is time-saving and very suitable to reconstitute large model soil specimens effectively and quickly.

Al-Ruhbah region is located in the southwest of Najaf Governorate. A numerical model was created to simulate groundwater flow and analyze the water quality of the groundwater, by developing a conceptual model within the groundwater modeling system software. Nineteen wells were used, 15 for pumping and four for observation. A three-dimensional model was built based on the cross-sections indicating the geologic layers of the study area, which were composed of five layers. When a distance of 1,000 m between the wells was adopted, 135 wells can be operated simultaneously. These wells were hypothetically operated at 6, 12, and 18 h intervals, with a discharge of 200, 430, and 650 m 3 /day, respectively, and the maximum drawdowns of 12.5, 15, and 21 m were achieved. Water was also extracted from five wells in the study area to evaluate the quality of water for irrigation purposes and to characterize the type of water in these wells based on the Food and Agriculture Organization and Iraqi standards. The results of the laboratory tests revealed that the water suffers from different salinity concentrations, so for a large part of the study area, the water is suitable for some plants that can withstand high salt ranges between 3,000 and7,500 µc/cm.

Increasing salinity in the Shatt Al-Arab River (SAR), south of Iraq, causes a serious issue with its water quality. In the current work, the proposed inflatable rubber dam was tested and verified for its feasibility and suitability on the SAR, Southern Iraq. The proposed rubber dam investigated its performance in reducing the salt front resulting from the seawater of the Arabian/Persian Gulf. Also, the inflatable rubber dam was feasibly compared with other types of hydraulic structure regulators and discussed the probable effect and benefits for each. Results of performance evaluation on the water quality were expressed in three groups: hydraulic, geotechnical, and economic performance. Results of the analyses of hydraulic indicators showed that the tide phenomenon has a significant impact on the water quality of the SAR. The geotechnical performance was assessed in terms of soil layers and was satisfactory. Analysis of the economic performance indicators showed that the inflatable rubber dam was feasible for the SAR problem compared with other types. Finally, a proposed design indicates the viability of inflatable rubber dam technology in controlling the salt front and improving the quality of the Shatt Al-Arab River water by reducing the salinity.

The building sector benefits from high-strength lightweight concrete (HSLWC) in various aspects, particularly in reducing the structure’s dead load. Incorporating waste materials into HSLWC encourages sustainable practices, reduces their environmental effect, and decreases product’s costs. This research focuses on producing sustainable HSLWC using a pumice stone and additive materials such as sugar molasses, silica fume, and high-range water reduction. The physical and mechanical properties and structural efficiency were investigated. The results demonstrate that the inclusion of additive material is the primary factor controlling the properties of the concrete. Also, using pumice stone instead of gravel in high-strength concrete significantly reduced weight and increased thermal insulation by 19.31 and 43.55%, respectively. Furthermore, the addition of steel fibers in HSLWC improved the compressive strength, tensile strength, ductility, and structural efficiency.

This study reports testing results of the transient response of T-shape concrete deep beams with large openings due to impact loading. Seven concrete deep beams with openings including two ordinary reinforced, four partially prestressed, and one solid ordinary reinforced as a reference beam were fabricated and tested. The effects of prestressing strand position and the intensity of the impact force were investigated. Two values for the opening’s depth relative to the beam cross-section dimensions were inspected under the effect of an impacting mass repeatedly dropped from different heights. The study revealed that the beam’s transient deflection was increased by about 50% with greater amplitudes for response oscillations due to impact loading as the impact force increased twice. The results showed that the transient strains in the reinforcement and concrete increased when increasing the opening depth with higher amplitudes for the response oscillations, whereas it had a minimal effect on the beam’s transient deflection. The reinforcement and concrete strain results indicated a higher damping for the strains as the prestressing strands were introduced. Comparison with solid deep beam response showed remarkable increase in the beam deflection and strains with greater amplitudes for response oscillations when large openings were introduced in the web.

Based on published test findings, this article outlines the use of artificial neural networks (ANNs) to forecast the efficiency factor of shear transfer strength in concrete. Backpropagation neural networks with feed-forward have been employed. The ANN model was created by incorporating a huge experimental database and carefully selecting the architecture and training procedure. The presented ANN model offered a more accurate tool to compute R (where R is a measure of the closeness of association of the points in a scatterplot to a linear regression line based on those points) and capture the impacts of five primary parameters: concrete compressive strength, steel reinforcement ratio, steel yield strength, fiber volumetric ration, and steel fiber aspect ratio are given from experimental data. The obtained results reveal that the first important parameter is concrete compressive strength. In addition, ρ y f y parameter represents the normalized tensile force in steel reinforcements of section, whereas the smallest importance parameter L / D is aspect ratio of steel fibers. Also, the current study illustrated the facilities of using generalized artificial neural networks on predicting the shear transfer strength across the concrete sections, whether they are fibrous or not. From the results, the correlation factor ( R 2 ) is estimated to be about 83%, which means it had a good correlation within the input parameters. In addition, the mean absolute percentage error was 2.06.

This study aims to simulate and assess the hydraulic characteristics and residual chlorine in the water supply network of a selected area in Al-Najaf City using WaterGEMS software. Field and laboratory work were conducted to measure the pressure heads and velocities, and water was sampled from different sites in the network and then tested to estimate chlorine residual. Records and field measurements were utilized to validate WaterGEMS software. Good agreement was obtained between the observed and predicted values of pressure with RMSE range between 0.09–0.17 and 0.08–0.09 for chlorine residual. The results of the analysis of water distribution systems (WDS) during maximum demand hours showed that the pumps unit capability cannot cover the high water demand during that time and resulted in a loss of pressure values, which were ranged between 0.2 and 2.1 bar. Moreover, the simulated results of the residual chlorine levels were within the permissible limits of 0.4–0.7 ppm, in different locations in the network. Providing good quality and adequate water supply is an important component for human life development. Modeling WDS is an efficient method of gaining a true understanding of the functioning of the network and determining the factors and conditions affecting the performance of the network.

The jet grouting method for soil improvement represents an innovative geotechnical alternative for problematic soils when the classic foundations’ designs cannot be appropriate, sustainable solutions for these soils. This study’s methodology was based on producing column models using a low-pressure injection laboratory setup designed and locally manufactured to approximate the field-equipment operation. The setup design was inspired by the works of previous researchers, where its functioning was validated by systematically performing unconfined compression tests (UCTs). Two soil improvement techniques were investigated, one by low-pressure injection of a mixture of water and ordinary Portland cement (OPC) with 0.8, 1, and 1.3 W/C ratios. The other type uses silica fume (SF) as a chemical additive with 10% of the cement weight added to the water and cement mix with 1, 1.3, and 1.6 W/C ratios. The study revealed that the UCT results of SF column model samples were higher than those of OPC with an equal W/C ratio. For each binder type, the UCT sample results increase with a decrease in the W/C ratio.

This study reports the effect of the magnetization process on the chemical and electrical properties of tap water (TW). Also, a step in the direction of gaining a better understanding of the influence of magnetizing technique on the physicochemical properties of water exposed to several intensities of magnetic field (MF). The TW sample used in this study passed through four intensities of the MF (2,000, 4,000, 6,000, and 8,000 G) under the same conditions of temperature and pressure. Magnetized water was tested and evaluated for physical and chemical qualities after being cycled through a magnetization device for 6 h. Following the increase in the intensities of the MF, the alteration in water properties has been depicted. The results showed increase in the pH value, electrical conductivity, and some of the chemical properties. The optimum change in the properties of water were obtained when the intensity of MF reached 8,000 G. However, to assess the obtained modification of water quality from the magnetization process, the results are compared with the guideline standards of the World Health Organization. To reduce the treatment costs and increase the long-term viability of the process, the study findings suggested a strategy of water magnetization as an effective treatment technology with reduction in energy and material usage (green technology).

Numerical models for impact load assessment are becoming increasingly reliable and accurate in recent years. The processing time duration for such analysis has been decreased to an acceptable level when combined with modern computer hardware. The aim of this study was to represent a simulation technique and to verify the validity of modern software in measuring the response of reinforced concrete beam strengthened by carbon fiber-reinforced polymer (CFRP) sheet subjected to impact loads at the ultimate load ranges. In this investigation, ABAQUS/Explicit Software’s nonlinear finite element modeling had been used. The response of the impact force–time history and the displacement–time history graphs were compared to the existing experimental results. The adopted general-purpose finite element analysis is verified to be capable of simulating and accurately forecasting the impact behavior for structural systems. In addition, a parametric analysis was carried out to gain a better knowledge of the performance of reinforced concrete beams under impact loading. Four parameters had been changed among the analyzed beams such as impact velocity, impact mass, CFRP sheet thickness, and compressive strength of concrete. Generally, it has been found that using a CFRP sheet in strengthening reinforced concrete beams can greatly improve the members’ impact behavior by improving stiffness as well as increasing load-carrying capacities. The enhanced performance characteristics of strengthening beams under impact loads correlate with the applied kinetic energy and CFRP thicknesses. Finally, for beams with high compressive strength, the deflection values were reduced because of the increase in stiffness.

The purpose of this study is to investigate the effect of an elastic wall on the peristaltic flow of Carreau fluid between two concentric cylinders, where the inner tube is cylindrical with an inelastic wall and the outer wall is a regular elastic sine wave. For this problem, cylindrical coordinates were used, and a short wavelength “relative to channel width for its length,” as well as the governing equations of Carreau fluid in the Navier–Stokes equations. Then, the analytical solution has been investigated by using the regular perturbation technique. The solutions obtained by this perturbation are up to the fourth-order in dimensionless Weissenberg number ( W e {W}_{{\rm{e}}} ). The performed computations of various parameter values such as velocity, shear stress, and wave frame streamlines are discussed in detail for different values of the Weissenberg number ( W e {W}_{{\rm{e}}} ). The obtained results demonstrate that the fluid velocity increases with the increase in the value of W e {W}_{{\rm{e}}} and some features of the wall, while the opposite behavior is observed with the increase in other features of the wall. Hence, the presented numerical analysis reveals many aspects of the flow by considering a non-Newtonian Carreau fluid model, and the presented model can be equally applicable to other bio-mathematical studies. The results were evaluated using the Mathematica software program. The Mathematica program was used by entering various data for the parameters, where the program showed the graphs, then the effect of these parameters became clear and the results were mentioned in the conclusion.

The present study aims to get experimentally a deeper understanding of the efficiency of carbon fiber-reinforced polymer (CFRP) sheets applied to improve the torsional behavior of L-shaped reinforced concrete spandrel beams in which their ledges were loaded in two stages under monotonic loading. An experimental program was conducted on spandrel beams considering different key parameters including the cross-sectional aspect ratio ( i.e. , web height/web thickness), and the availability of the CFRP strengthening system. The ledge of the spandrel beams was exposed during testing to a very high eccentric load, which was transferred to the web of the spandrel beam causing high shear, torsion, and bending moments. Consequently, the applied load resulted in in-plane and out-of-plane deformations of the web accompanied by flexural and shear cracks. This article demonstrates the advantage of using CFRP sheets to strengthen the mentioned members. The applied CFRP sheets increased the failure torsional load by about 37% compared to the identical L-spandrels without strengthening. The outcomes indicate that using CFRP sheets show improvement in restricting the deflections and rotation of L-spandrels due to increasing spandrel stiffness. The reduction in the degree of rotation attained more than 33% in comparison to the spandrel beams without strengthening. The experimental program confirmed the applicability of the proposed strengthening technique for compacted and slender L-shaped spandrel-reinforced concrete beams.

Until recently, the behavior of connected piled raft foundation was not fully understood in the seismically active region due to the complex dynamic soil–pile–foundation structure interaction. This concern arises when the soil deposit-supported foundations are stratified or heterogynous and subjected to high ground motion intensity. In the current study, a series of numerical analyses using ABAQUS software have been conducted on a pile group of (3 × 3) arranged into a square pattern to investigate the seismic response of piled foundations embedded in dry sandy soil (homogenous and layered), and how the amplification of propagated waves affects the bending moment along piles. For mesh generation, an artificial boundary condition using the tied-nodes approach was adopted to simulate the free-field motion of soil under earthquake excitation. The structure used a single degree of freedom with a lumped mass. Moreover, Mohr–Coulomb and linear elastic models have been chosen for soil and pile–raft, respectively. The results demonstrate that the foundation rocking increases in stratified soil compared to homogenous soil, irrespective of the seismic intensity. The maximum bending moment was observed at the pile head in homogenous soil and shallow depths in layered soil because of the kinematic interaction at the soil interface. The results also indicated that the amplification factor (acceleration at a certain depth to the acceleration at bedrock) was found to be 203 and 189% in homogenous soil for PGA values of 0.1 and 0.33  g , respectively. Almost there were no effects of seismic intensity in layered soil on the amplified waves transmitted into the soil surface.

The dynamic response of the retaining structures is a complex issue, and a major challenge in their design, especially under seismic loading conditions. So a reliable and efficient solution following a computational approach, closer to reality, is required to obtain satisfactory results. Hence, this study came to clarify the effectiveness of the PLAXIS 3D program in predicting the performance, accuracy, and reliability of retaining walls. A case study of placing compressed materials as the backfill of the retaining wall soil is analyzed in this study using PLAXIS 3D software. The results are compared with the experimental results and the results of PLAXIS 2D software. The purpose is to predict the performance of retaining walls under seismic loads. As a result, the research stated that the displacement with time was less than the results recorded depending on the program PLAXIS 2D. According to the comparison of the different analytical tools, the researchers concluded that the adoption of the PLAXIS 3D program gives results that are closer to reality, more accurate, and more reliable.

In this study, the effect of location of surcharge load on the stability and behavior of the retaining wall under static and dynamic load has been considered. A cantilever retaining wall of 7 m height retained dry sandy soil with 50 kN/m 2 surcharge load. Several parameters were taken into account in the numerical analysis, including the horizontal distance ( X ) from the edge of the wall to the surcharge load expressed as a ratio to the heel width ( X/B h = 0, 0.25, 0.5, 0.75, and 1), as well as the effect of different values of the earthquake's horizontal component ( k h = 0.1, 0.2, and 0.3). Lateral earth pressure distribution decreases with increase ( X / B h ) in the upper one third of the wall. The effect of surcharge location at the top of the wall disappears at X / B h = 0.25. Under dynamic load, the maximum displacement at the top of the wall is obtained at X / B h = 0.5. It is increased by about 4 times at k h = 0.3. The possibility of sliding increases by about 4.8 times once the k h increases from 0.1 to 0.3. There is a maximum increase in rotation by 2 times at k h = 0.1. In the dynamic case, the differential settlement decreases with increase in X / B h , and increases with the increase in k h .

Organic soil is a problematic soil that needs to be treated before construction because of the low shear strength and high compressibility. Using by-product materials, such as fly ash (FA), to improve soils is a cost-effective and sustainable procedure. Because treatment with FA may lead to reduce shear strength, a FA-based geopolymer was used with a cohesive organic soil to substitute the reduction in strength. A series of unconfined compressive strength tests (UCS) were conducted on compacted specimens treated with FA and geopolymer. The geopolymer was produced by adding sodium hydroxide to activate the FA. Different levels of FA content, curing period, and temperature were applied to the specimens. The results indicate that for the FA treated specimens, the UCS decreased as the FA increased. For the geopolymer-treated specimens, as FA percentage in the geopolymer increased, the UCS increased and the axial strain at failure decreased. The optimum content of FA, in the geopolymer, was 20%, and the highest UCS was achieved at a curing period of 28 days at a temperature level of 65°C. Based on the obtained results, FA-based geopolymer can effectively be used to improve the strength of organic soils.

An earthquake is a random phenomenon in its intensity and frequency content. Since the earthquake is a signal that contains a band of frequencies, each frequency has a different energy. This means that the response of buildings to earthquakes depends not only on the intensity of the earthquake but on its frequency content as well. In this study, two different approaches have been used: deterministic approach which is the time history analysis to show how the intensity of earthquakes affects the building response, and the nondeterministic random vibration approach, which is to clarify the response in the frequency domain and to show the effect of dominant frequencies of the earthquake. Both a prototype and a 1:6 scaled model was used to simulate a two-story steel building. In the experiential part, a shaking table was used to simulate a 1:6 scaled El-Centro 1940 NS earthquake as a base excitation with different intensities (0.05, 0.15, and 0.32 g ). In the theoretical part, Abaqus software was adopted to simulate the numerical model of the building. The results showed that the deterministic approach may be a non-conservative approach.

Studies on the behavior of reactive powder concrete (RPC) columns under eccentric loading are limited. The effect of materials used in manufacturing these RPC columns has not yet been investigated. This research aimed to perform a nonlinear-finite-element analysis to determine the load-carrying capacity and displacement of RPC columns made of different RPC mixes and subjected to various loading eccentricities. This research investigates two types of parameters. The first parameter is the column’s geometric parameters (the height L and the load eccentricity distance e ). The second is the RPC material parameter (regarding the silica fume or fly ash used as pozzolanic material and the type of fibers used, whether steel or glass fiber). Results indicate that eccentric-loaded slender columns exhibit much less load-carrying capacity than the corresponding short columns. The 2 m-long columns with eccentricity ratio e / t = 0.2 resulted in a 65% average reduction in the ultimate load (Pu) compared to the corresponding 1 m-long columns. Using fly ash as a pozzolanic material instead of silica fume reduces the ultimate load (Pu) of an RPC column by an average of 60%. Using glass fibers instead of steel fibers also reduced Pu by 50%. The average percentage increase in the maximum vertical deflection (Δ y max ) of the short column ( L = 1 m) is found in the range of 18–31% for eccentricity ratio e / t = 0.1 but 45–69% for e / t = 0.2. In contrast, for a slender column ( L = 2 m), the percentage increase in Δ y max is in the range of 10–30% for both e / t = 0.1 and 0.2.

The application of two different lateral loads ( i.e., the first is static and the other is cyclic load) at the same time to pile group seems a complex problem. So, this study is concerned with the interaction of these loads together and includes laboratory tests to determine the effect of the static lateral load on the lateral cyclic capacity of the 2 × 2 pile group with three distances ( S / D = 3, 5, and 7). The experimental program included small-scale laboratory setup by using hollow piles of aluminum and sand rain method for the preparation of sandy soil medium. The results showed that increasing the static lateral load led to reducing the lateral displacement, and the average value of decrease for the three distances reaches 72%. It can also be concluded that the distance S / D = 3 is more affected by the increase in the static lateral load than other distances, where the average decrease in the lateral displacement was about 83, 74, and 60% when S / D = 3, 5, and 7 sequentially.