Maximum Load-carrying Capacity Research Articles

A Comparative Study on Hydrodynamic Analysis with and without Cavitation Modelling: A Study on Textured Slip Journal Bearing

In journal bearing modeling, the phenomenon of cavitation is very important to improve the accuracy of the simulation results. This is because cavitation will almost certainly occur because there are convergent and divergent geometries. The results of the simulation will be close to real conditions so that it can have a positive effect on researchers in order to design optimal journal bearings. The effect of modeling without cavitation and with cavitation on journal bearing modeling has a great influence on the lubrication performance of journal bearings. In modeling with cavitation, the maximum hydrodynamic pressure and load carrying capacity that the journal bearing is capable of relying on has a fairly rapid increase. The modeling results also relate to the friction force that occurs in the journal bearing. The aim of the present study is to explore the effect of inclusion of modeling of the Hydrodynamic pressure. The finite volume method based on software is used to compare the result with and without cavitation. Here, The mixture multiphase cavitation is adopted. The numerical result show t he effect of modelling without cavitation and with cavitation on journal bearing modelling has a great influence on the lubrication performance of journal bearings. In modelling with cavitation, the maximum hydrodynamic pressure and load cmarrying capacity that the journal bearing is capable of relying on has a fairly rapid increase. The modelling results also relate to the friction force that occurs in the journal bearing.

Performance analysis of columnar convex-concave compound microtexture thrust bearing

PurposeThis study aims to enhance the lubrication performance of thrust bearings. The influence of columnar convex–concave compound microtexture on bearing performance is investigatedDesign/methodology/approachBased on the compound microtexture model of thrust bearings, considering surface roughness and turbulent effect, the variation of lubrication characteristics with the change in the compound microtexture parameters is studied.FindingsThe results indicate that, compared with circular microtexture, the maximum pressure of compound microtexture of thrust bearings increases by 7.42%. Optimal bearing performance is achieved when the internal microtexture depth is 0.02 mm. Turbulent flow states and surface roughness lead to a reduction in the optimal depth. The maximum pressure and load-carrying capacity of the bearing decrease as the initial angle increases, whereas the friction coefficient increases with the increase in the initial angle. The lubrication performance is best for bearings with a circumferential parallel arrangement of microtexture.Originality/valueThe novel composite microtexture with columnar convex-concave is proposed, and the computational model of thrust bearings is set. The influence of surface roughness and turbulent flow on the bearing performance should be considered for better conforming with engineering practice. The effect of microtexture depth, arrangement method and distribution position on the lubrication performance of the compound microtexture thrust bearing is investigated, which is of great significance for improving tribology, thrust bearings and surface microtexture theory.

An experimental investigation and cost analysis of flexural or shear strengthening pre-damaged RC beams

This study conducted a series of experimental works to repair and strengthen beams with different flexural and shear damage levels using various repair/strengthening techniques such as carbon fiber-reinforced polymer (CFRP), steel plate (SP), and mechanical steel stitches (MSS). Within the scope of the study, post-strengthening performances of pre-damaged shear beams and flexural beams were investigated. For this, 1/2 geometrical scaled 20 reinforced concrete rectangular cross‐section beams, with dimensions of 125/250 mm and a span of 2500 mm, were produced. Half of these beams (type-SB) were designed to meet shear damage due to insufficient shear reinforcement, while the other half (type-BB) was designed to undergo flexural damage (sufficient shear reinforcement). Subsequently, a reference beam was produced in both shear and bending test groups, the other beams were strengthened with different techniques, and four-point bending tests were performed. Reference (non-damaged) bending and shear beams were vertically loaded and comprehensive data for these specimens were obtained. Later, the flexural beams (type-BB) were vertically loaded until reaching mid-displacement/span length (δu/L) ratios of 1%, 2%, and 3% of the flexural reference beam, while the shear beams (type-SB) were loaded up to 50%, 65%, and 85% of the maximum load-carrying capacity (Pmax) of the shear reference beam to induce different damage levels. Then the specimens were strengthened with three strengthening methods (CFRP, SP, and MSS). The data obtained from the experiments were compared, considering each group specimen's strength, displacement ductility, stiffness, and energy dissipation capacity. In addition, the cost of each strengthening type was calculated, and the ratio of the strengthening costs / the production cost of the element itself was determined. According to load carrying capacity and ductility behavior, experimental studies have shown that CFRP has proven to be more effective for type-BB beams (3% pre-damaged level), whereas MSS has proven to be more effective for type-SB beams (85% pre-damaged level) than other methods. While both MSS and SP have been effective for all damage levels in BB beams, CFRP has only shown effectiveness for a damage level of 3%. In the case of shear beams, the load-carrying capacity has increased for various damage levels with CFRP, SP, and MSS. However, typical bending beam behavior was exhibited for CFRP 85%, SP 65%, and MSS 85% load levels. It was also determined that SP and MSS contributed to the ductility orientation for the 65% damage level. However, in terms of cost, CFRP was the most expensive, whereas MSS was the least expensive strengthening method. CFRP was approximately twice as costly as SP and three times more costly than MSS. Finally, due to its ease of application and low cost, MSS, which is a relatively new strengthening technique, has been found that the MSS method is a better alternative than other methods, especially for the strengthening of beams that have received shear damage.

Experimental Study and Bearing Capacity Calculation of Compression-Reinforced Concrete Columns Strengthened with Ultra-High-Performance Concrete

A total of five ultra-high-performance concrete (UHPC)-strengthened reinforced concrete (RC) columns and one RC column were built and subjected to eccentric compression testing to examine the force performance of UHPC-strengthened eccentrically compressed plain RC columns. This experimental study examined the crack progression, the damage morphology, the deformation ability, the maximum load-carrying capacity, and the ductile properties of the eccentrically compressed columns. It also investigated the impacts of eccentricity, the reinforcement thickness, and the addition of steel fibers on the effectiveness of reinforcement. The cracking load, peak load, and ductility coefficient of the UHPC-reinforced specimens were increased by 100.28%, 172.30%, and 56.30%, respectively, compared with the RC column at an initial eccentricity of 50 mm. As the eccentricity distance increased, the bearing capacity of the UHPC eccentrically compressed specimens decreased, and the deformation capacity increased. Increasing the steel fiber dosage within the appropriate range decreased the crack width of the specimen. The addition of 2% steel fiber resulted in a 24.8% increase in cracking load, an 8.96% increase in peak load, and a 2.60% increase in ductility coefficient compared to the addition of 1% steel fiber. However, the reinforcing effect of UHPC was weakened under high eccentric pressures. Based on the theory of concrete structure and mechanical principles, the formula for calculating the compressive bearing capacity of RC columns strengthened with high-performance concrete was proposed. The results of calculating the positive section bearing capacity of eccentrically compressed RC columns reinforced with high-performance concrete are in good agreement with the test values. The results of this paper provide an experimental basis and theoretical foundation for the cross-sectional design of UHPC eccentrically compressed columns.

Retrofitting of squat RC column by using TRM strip under axial load

This study investigates the retrofitting of reinforced concrete columns with TRM strips. Seventeen test specimens were produced, and one was chosen as a reference test specimen. Damaged by loading up to 50% of their maximum axial load-carrying capacity test specimens were retrofitted with two different carbon textiles. In addition to the textile type, TRM strip width, strip spacing, and the use of anchors were determined as experimental variables. Maximum bearing capacity, displacement at bearing capacity, initial stiffness, displacement ductility ratio, and energy consumption capacity were calculated using the axial load-displacement graphs obtained from the experimental study. Depending on the obtained results, the effects of experimental variables on the behavior of damaged reinforced concrete columns were interpreted and compared. It has been determined that the retrofitting method presents very successful results. It has been observed that the fan-type anchor, which is rarely used in literature studies, significantly increases the maximum bearing capacity and energy consumption capacity values of test specimens. Finally, the experimental results were compared with those obtained from the numerical models created by the ABAQUS finite element software.

Axial compressive behavior of recycled aggregate concrete steel composite columns

In this Study the axial load-carrying capacity and behavior of a “Axial Compressive behavior of Recycled Aggregate Concrete Steel Composite Columns” (RACSCC) is investigated experimentally and simulated numerically. The study emphasizes the utilization of materials contributing to the circular economy in construction, specifically integrating steel and recycled aggregate into concrete. The environmentally sustainable concrete columns are formed by filling square steel tube sections with recycled aggregate concrete (RAC). The study includes six SRACC specimens and one bare conventional steel column. The specimens are subjected to axial compressive loading using the displacement control method. The investigation explores the impact of different coarse aggregate sizes of 12 mm, 16 mm, 22.4 mm, 25 mm, and 30 mm, obtained through sieving of demolished buildings materials. The study aims to address the impact of varying aggregate sizes on parameters such as maximum load-carrying capacity, strain, stress, lateral displacement, and failure patterns. The experimental results are validated and compared with the maximum load-carrying capacity, Strain, Stress, Lateral displacement, and failure patterns using numerical simulations conducted with the Ansys Workbench tool. The SRACC column comprises a hollow tube with 20 mm to 22.4 mm and 22.4 mm to 25 mm recycled aggregate and has a maximum load carrying capacity of 610.28 kN at 10 mm displacement. The local buckling failure occurred near the area load applied. The numerical simulations result for the composite columns agreed well with the experimental results. The results show the recycled aggregate concrete (RAC) have a massive potential for construction support in circular economy. To create composite columns using the RAC as an alternative building material that will help to create an environmentally Sustainable construction

Experimental Investigation of High-Force-To-Volume Extrusion Damper Subjected to Cyclic and Time History Loading

Abstract The ability of energy dissipation from earthquake force in a controlled and iterative manner will play a vital role in maintaining structural reliability for various forces. High force-to-volume (HF2V) extrusion damper is a promising technology with simple designs, high damping force and achieving design requirements. This paper develops HF2V extrusion damper with multiple toothing configuration for seismic application. The experimental verification has been undertaken on lead extrusion dampers with various frequency range of 0.5 to 2 Hz. The maximum load-carrying capacity is 10.48 kN with strokes up to 5mm are observed with hysteresis loop with some recentering capability has a stiffness value up to 2*106 N/m, and force levels up to 2-10 kN. The maximum load carrying capacity for time history loading for Northridge earthquake is 11.57 kN. The overall findings suggest that silicone sealant may be employed to build and characterize extrusion dampers with maximum energy dissipation and high force/volume interactions. The suggested device may be a potentially effective way to provide additional energy dissipation to structures in seismic zones, according to the mechanical characteristics to the frequency. Additionally, the system can withstand for earthquake time histories, and ensuring maintenance-free operation even in the midst of frequent ground vibration.

Monotonic and cyclic behaviour of deficient reinforced concrete slabs retrofitted with externally bonded carbon fibre reinforced polymer

Fibre reinforced polymer (FRP) retrofitting of reinforced concrete (RC) slabs has been widely investigated; however, the flexural behaviour of deficient RC slabs retrofitted with FRP under cyclic loading are limitedly explored. Towards this aim, this study experimentally and theoretically investigated the behaviour of RC slabs retrofitted with carbon fibre reinforced polymer (CFRP) under monotonic/cyclic loadings. Seven full-scale RC slabs, including one control slab and six slabs retrofitted by 1/2 and one CFRP layer, namely retrofitting types I and II, were tested under monotonic and cyclic loadings until failure. The results indicated that FRP retrofitted slabs failed by CFRP debonding while the control slab failed by steel yielding. CFRP retrofitted slabs exhibited tri-linear behaviour. CFRP retrofitting types I and II improved the yield load-carrying capacity by 43.5% and 83.5%, and the maximum load-carrying capacity by 81.9% and 217.4% compared with the capacity of the control slab, respectively. The stiffness of the retrofitted slabs increased significantly, leading to a substantial reduction in the deflection capacity. Although the ductility decreased, the safety factors based on load-carrying capacity of CFRP retrofitted slabs were much higher than the safety factor of the control slab. Cyclic loading caused a marginal strength degradation while it slightly reduced the ultimate deflections. Finally, a model to compute the moment capacity of CFRP retrofitted slabs was proposed, which can be useful for engineers in practice due to its simplicity and reasonable accuracy.

High-accurate FE simulation on compressive behavior of steel cruciform column with welding imperfection

Due to its various advantages, welding is commonly used in the construction for steel connection. However, the local temperature difference in the welding causes welding deformation and residual stress. The welding deformation and residual stress can significantly impact the load-bearing performance of members. Therefore, it is important to evaluate those behaviors with high precision. In the previous studies, thermal elastic-plastic analysis was used to evaluate welding deformation and residual stress in simulated welded specimens and the compressive simulation was applied to obtain, for example, the load-bearing performance. Nevertheless, there are limitations in assessing structures made up of thin plates. This is because the simulation of welding is typically modeled using solid elements, while the simulation of loading analysis uses shell elements. As a result, these analysis steps are not directly related, leading to deficiencies in the evaluation process. In this study, the solid element model and shell element model were modeled to simulate the welding deformation and residual stress. The corresponding load-bearing capacity results obtained from the continuous loading analysis were compared with the results from experiment to verify the consistency. According to the results, shell models that perform welding analysis simulation followed by continuous compressive analysis are better able to replicate experimental results in terms of out-of-plane deformation and maximum load-carrying capacity under compressive analysis. This is in contrast to solid models, which fall short in reproducing the same results. Moreover, the shell model is also more efficient than the solid model in terms of time saved during analysis and calculation.

Shear strength model for steel shape-reinforced concrete girders considering compatible steel–concrete interaction

Steel shape-reinforced concrete (SRC), also known as concrete-encased steel, offers numerous benefits compared with conventional reinforced concrete (RC) or bare steel due to its combination of RC and structural steel sections; therefore, SRC members find extensive use as transfer elements or girders in engineering applications. When evaluating SRC girders’ shear resistance, the direct strength superposition of RC and structural steel is basically used in most design codes, ignoring the steel–concrete interaction under shear, which has proven unreasonable because of the brittle shear behavior of RC. This paper suggests a novel method for assessing SRC girders’ shear resistance mechanism. The proposed method involves modeling the RC portion by a hybrid truss-arch analogy; in addition, based on the strain compatibility condition, the steel profile’s contribution is determined by applying the yielding criterion. Finally, the rationality of the proposed model is validated through a comprehensive comparison with previously published models and a set of 45 experimental test data samples available in the existing literature, and the results show that the proposed model can reasonably predict the maximum load-carrying capacity of SRC girders and is superior to existing shear strength models and code-based equations.

Vibration characteristics of turbocharger rotor system considering internal thread texture parameters of semi-floating ring bearing

The internal thread texture causes changes in the dynamic characteristics of the oil film of the semi-floating ring bearing, which affects the amplitude of vibration and operating life of the turbocharger rotor system. Based on the fluid lubrication theory, the oil film governing equation of a semi-floating ring bearing with surface texture parameters is derived. The effects of the texture depth, position, and number of turns of the internal thread on the dynamic characteristics of the bearing oil film, such as the maximum pressure, load-carrying capacity and stiffness damping, are analyzed. Taking a type of turbocharger as an example, a hydrodynamic model is established to analyze the oil film lubrication in the semi-floating ring bearings, and the dynamic characteristic of the oil film is analyzed by computational fluid dynamics method. The results show that the maximum pressure, bearing capacity, and stiffness damping coefficient of oil film increase firstly and then decrease with the increase of texture depth and the number of thread turns in the range of journal rotation speed from 1000 to 20,0000 r/min. Compared with the non-texture bearings, the dynamic characteristics coefficients of the oil film such as bearing capacity and stiffness damping increase the most, when the depth of texture is 0.006 mm and the number of thread turns is 9. Secondly, the dynamic characteristic coefficient of oil film is improved when the texture is distributed in the middle than on both sides. The thread texture with appropriate parameters can suppress the rotor system vibration amplitude. The conclusion can provide a reference for the design of textual parameters of semi-floating ring bearings.

Experimental and numerical investigations of tensile behavior of slip-critical blind bolts anchored in concrete-filled steel tubes

This paper presents experimental and numerical investigations of a Concrete-Anchored Slip-Critical Blind Bolt (CASCBB) system, which can be used to connect a steel beam to a concrete-filled steel tube column to form a rigid moment connection. A series of pull-out tests of CASCBBs embedded in concrete-filled steel square hollow section (SHS) is conducted with varying parameters such as with or without concrete infill, types of bolts, threaded or non-threaded anchor stud, tube thickness and bolt edge distance. A connection with a sufficiently thick SHS flange benefits significantly from its direct contribution to the total resistance even well before the anchorage failure. If the tube flange is too thin, the connection will possess no ductility as the concrete cone failure mode governs and dominates. A finite element methodology that resolves the difficulties of modelling the behaviour of infill concrete housing an anchored bolt is able to closely replicate the experimental responses. It is found from the finite element analysis that the contribution of the steel tube’s flange is independent of its thickness-to-width ratio but is a function of its thickness and the bolt edge distance. Placing the anchored bolt close to the SHS web can double the stiffness compared to placing it in the middle of the flange due to the greater contribution of the steel tube. It can also increase the maximum load-carrying capacity significantly. The finite element analysis results suggest that threading the anchor stud does not have noticeable effects on the anchorage failure load and the connection’s stiffness, in contrast to the apparent test results. In order to enable the plate separation to take place (at a load slightly higher than the bolt pretension), the column wall must be sufficiently thick. The wall thickness controls the maximum tensile capacity, the elastic stiffness and the ductility, but does not affect the initial stiffness.

Verification of Truss-Arch model unified for RC beams with stirrups using shear database

A shear strength analysis model called “Truss-Arch Model Unified (TAMU)” was proposed for shear-critical reinforced concrete (RC) beams with transverse reinforcement. The TAMU has its roots in the Compatibility Strut-and-Tie Model (C-STM) which is a computational modeling approach for the overall force–deformation analysis of deep beams. The TAMU simplified the C-STM so that a limited analysis can be executed by hand methods of analysis to predict the maximum load-carrying capacity of RC deep beams. While the tensile stress of concrete is generally taken into account to evaluate the shear strength of RC beams, the TAMU limit analysis focuses on the strength reduction of the principal diagonal concrete arch due to the transverse principal tensile strain. In the present study, a shear database is assembled from previous works reported in the literature to further substantiate the validity of the TAMU approach. The shear database consists of tested RC beams with shear reinforcement whose shear span-depth ratios (a/d) are between 0.5 and 4.5. Comparative TAMU analysis results show satisfactory agreement with the ultimate strengths observed in 460 RC beam tests regardless of D- and B-regions, demonstrating the method’s ability to predict the maximum load-carrying capacity for shear-critical beams. Additionally, the TAMU approach shows better accuracy and consistency against the database compared to AASHTO sectional shear design methods. The probability of reasonable prediction of the TAMU method is 92% in d-regions and 78% in B-regions, respectively, which is significantly higher than those of AASHTO sectional shear design methods, especially in d-regions. Thus, the TAMU method may be a viable improvement as an alternative strength analysis method for shear-critical RC beams with transverse reinforcement.

Influence of Isolated Resistance Exercise on Cardiac Remodeling, Myocardial Oxidative Stress, and Metabolism in Infarcted Rats.

Exercise is an important therapeutic strategy for preventing and treating myocardial infarction (MI)-induced cardiac remodeling and heart failure. However, the myocardial effects of resistance exercise on infarcted hearts are not completely established. In this study, we investigated the effects of resistance exercise on structural, functional, and molecular cardiac alterations in infarcted rats. Three months after MI induction or simulated surgery, Wistar rats were assigned into three groups: Sham (n = 14); MI (n = 9); and exercised MI (MI-Ex, n = 13). Exercised rats performed, 3 times a week for 12 weeks, four climbs on a ladder with progressive loads. Cardiac structure and left ventricle (LV) function were analyzed by echocardiogram. Myocyte diameters were evaluated in hematoxylin- and eosin-stained histological sections as the smallest distance between borders drawn across the nucleus. Myocardial energy metabolism, lipid hydroperoxide, malondialdehyde, protein carbonylation, and antioxidant enzyme activities were evaluated by spectrophotometry. Gene expressions of NADPH oxidase subunits were evaluated by RT-PCR. Statistical analyses were performed using ANOVA and Tukey or Kruskal-Wallis and Dunn's test. Mortality did not differ between the MI-Ex and MI groups. MI had dilated left atrium and LV, with LV systolic dysfunction. Exercise increased the maximum load-carrying capacity, with no changes in cardiac structure or LV function. Myocyte diameters were lower in MI than in Sham and MI-Ex. Lactate dehydrogenase and creatine kinase activity were lower in MI than in Sham. Citrate synthase and catalase activity were lower in MI and MI-Ex than in Sham. Lipid hydroperoxide concentration was lower in MI-Ex than in MI. Nox2 and p22phox gene expressions were higher in MI-Ex than in Sham. Gene expression of Nox4 was higher in MI and MI-Ex than in Sham, and p47phox was lower in MI than in Sham. Late resistance exercise was safe in infarcted rats. Resistance exercise improved maximum load-carrying capacity, reduced myocardial oxidative stress, and preserved myocardial metabolism, with no changes in cardiac structure or left ventricle function in infarcted rats.

Numerical investigation on the shear behavior of slender reinforced concrete beams without shear reinforcement differed by various boundary and loading conditions

This paper presents a numerical investigation on the shear behaviour of reinforced concrete beams without shear reinforcement differed by two boundary conditions, i.e., cantilever and simply supported beam, and two loading configurations, i.e., one-point and uniformly distributed load. The finite element models are exactly constructed as specimens of an experimental program that investigates the effect of the bending moment on the shear response of members without shear reinforcement. Similar to the experimental observations, the finite element analyses show general differences in the shear resistance of members having the same cross-sectional properties but diverse M/V–combinations resulting from different support and loading conditions. For the same cross-sectional parameters, the shear resistance of the simply supported beam subjected to a uniformly distributed load is higher than that of cantilevers subjected to a concentrated load, and the shear resistance of the cantilevers subjected to a uniformly distributed load is higher than that of the simply supported beam. Through finite element analysis, more insight of this effect can be obtained by the investigations of the strain profile in the cross-section, the principal stress within the shear span, and the stress distribution at the longitudinal flexural reinforcement. Furthermore, the difference between the shear force at the critical shear crack formation and the maximum load-carrying capacity is distinguished by analyzing the governing load transfer mechanism. The validated FE models are used to investigate the influence of shear slenderness on the shear resistance of beams by various boundary and loading conditions. A comparison to the shear resistances predicted by design equations proposed in some codes of practice is also provided.

Stress–Strain Assessment of Honeycomb Sandwich Panel Subjected to Uniaxial Compressive Load

The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the structural integrity, economy, safety and environmentally friendly design of the ship’s hull structure. A new design solution may be represented by aluminium alloy honeycomb sandwich structures, both as plane panels or stiffened ones, which are characterised by excellent impact-absorption capabilities and a high stiffness-to-weight ratio. Still, their response to some conditions typical of ship structural design needs to be deeply investigated. Axial compressive loading is one of the most critical conditions that could impact the structural integrity of such light-weight solutions. Hence, the uniaxial compressive behaviour of aluminium honeycomb sandwich structures has to be deeply investigated to promote their integration in ship structural design. Within this context, the present work performs an experimental and numerical study of a honeycomb sandwich panel subjected to uniaxial compressive loads. The results will help develop models for predicting the uniaxial compressive load-carrying capacity of hybrid honeycomb sandwiches of aluminium alloy design.

Complibot: A compliant external pipe climbing robot

The article presents the design of Complibot, a robot with a novel gripper for pipe climbing. The mechanism of the gripper involves the use of a bistable buckled beam, which is a type of bistable compliant mechanism. The bistable buckled beam in the gripper is alternately actuated between its gripped and ungripped states using a camshaft and lever mechanism, which is powered by a single DC motor. The design parameters associated with the gripper are obtained both experimentally and numerically. A proper selection of design parameters helps in the efficient functioning of the gripper. After the design of the gripper, two such grippers are fabricated and attached to each other by two stepper motor-driven lead screws to make a pipe climbing robot with inchworm locomotion. The mobility of the robot is controlled by an Arduino Uno microcontroller after the electronic components have been integrated. Finally, Complibot is subjected to a series of tests to establish its maximum load-carrying capacity when climbing a polyvinyl chloride (PVC) pipe. Complibot is found to perform satisfactorily without slipping while climbing a PVC pipe with a diameter of 105–115 mm, a velocity of 0.2 m/min, a power consumption of 18.58 W, a maximum load-carrying capacity of 114.64 N, and a payload to weight ratio of 0.52.

Performance of Reinforced Concrete Gable Beam with Quadrilateral Openings of Different Side Inclinations

The existence of openings in a gable beam would have numerous advantages, the most important of which would be a reduction in the overall weight. These advantages include geometric flexibility, ease of handling when erected, and more. This study aims to investigate the flexural behavior of reinforced concrete gable beams with quadrilateral openings of different side inclinations; this goal has been specified with beam stiffness, the maximum load-carrying capacity, and strains of the beams. Beams are identical in their dimensions and reinforcement. The experimental program involved casting and testing four simply supported beams: a solid beam (reference beam) and others with quadrilateral openings. They were 3000mm long, 100mm wide, and 400 mm deep in the middle, tapering to 250 mm on both ends, concentrically loaded. The results demonstrate the load-carrying capacity is reduced by 6.1–12.9%, and the mid-span deflection is increased by 13–52% when openings exist compared to the solid gable beam. Enhancement represented by increases in strength and decreases in deflection was observed when the inclination of the quadrilateral side opening decreased from 90 to 60 and then 45o, respectively. In contrast, the total opening area was maintained. The creation of openings in concrete gable beams can reduce their weight by about 12.5%.

Analysis of Pollutant Load Carrying Capacity of the River Tapi Using QUAL2Kw for Surat City

River Tapi is the prime water body for Surat city, Gujarat, India. On a long stretch of 22.39 km in Surat city (Kamrej to Causeway) of the Tapi river, there are many identified and non-identified discharge points available. Excessive discharge from these points restricts the efficiency of the self-purification process which ultimately degrades the river water quality. In this paper, an attempt has been made to estimate the pollutant load-carrying capacity at different segments of the river Tapi using the QUAL2Kw tool. The study has been undertaken with different scenarios: First, the QUAL2Kw model was trained with available river water quality and hydraulic data of the Tapi river in which the complete river segment was divided into 21 reaches. The model was calibrated and validated with the actual concentrations of the pollutants entering. In the second phase, all the point source, non-point source, and headwater characteristics were considered and the pollutant load-carrying capacity of the river in terms of BOD, ISS, and N-nitrate was found. In the third phase, all the sources of pollutants entering the river have been removed and only headwater characteristics were considered for the study. The results indicate that reach no. 21 (21.23ºN, 72.82ºE) has the maximum load-carrying capacity of Biochemical Oxygen Demand (BOD) up to 2057.7 kg/day, Inorganic Suspended Solids (ISS) up to 85633.8 kg/day, and Nitrate (NO3) up to 31688.8 kg/day. However, reach no. 4 has the minimum load carrying capacity of BOD up to 1088.1 kg/day, reach 8 carries a minimum of ISS 205341.6 kg/day and NO3 10215.57 kg/day.

Performance of Sustainable Insulated Wall Panels with Geopolymer Concrete.

The increase in the population creates an increased demand for construction activities with eco-friendly, sustainable, and high-performance materials. Insulated concrete form (ICF) is an emerging technology that satisfies the sustainability demands of the construction sector. ICF is a composite material (a combination of expanded polystyrene (EPS) and geopolymer concrete (GPC)) that enhances the performance of concrete (such as thermal insulation and mechanical properties). To investigate the axial strength performance, five different types of prototypes were created and tested. Type I (without reinforcement): (a) hollow EPS without concrete, (b) alternative cells of EPS filled with concrete, (c) and all the cells of EPS filled with concrete; and Type II (with reinforcement): (d) alternative cells of EPS filled with concrete; (e) and all the cells of EPS filled with concrete. Amongst all the five prototypes, two grades of GPC were employed. M15 and M20 grades are used to examine the effectiveness in terms of cost. For comparing the test results, a reference masonry unit was constructed with conventional clay bricks. The main aim of the investigation is to examine the physical and mechanical performance of sandwich-type ICFs. The presence of polystyrene in ICF changes the failure pattern from brittle to ductile. The result from the study reveals that the Type II prototype, i.e., the specimen with all the cells of EPS filled with concrete and reinforcement, possesses a maximum load-carrying capacity greater than the reference masonry unit. Therefore, the proposed ICF is recommended to replace the conventional load-bearing system and non-load-bearing walls.