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In the context of green building and sustainable urban development, understanding the mechanical behavior of structural components like concrete-filled steel tube (CFST) columns is crucial due to their improved load-bearing capacity, energy efficiency, and optimized material usage, which enhance structural resilience and sustainability. This research addresses the complex development of confining stress and its impact on the concrete core (CC) behavior within these columns, which are essential for urban infrastructure. Through extensive numerical studies, this study proposes a model to estimate the confining stress in axially loaded CFST short columns. Study findings reveal that the confinement effectiveness is influenced by variables such as compressive strength (CS) of the concrete, cross-sectional shape, and depth-to-wall thickness percentage. Additionally, the confinement is also significantly affected by the yield strain of steel εy/εc to the peak strain of unconfined concrete εc. A three-dimensional finite element model (FEM) was built for the simulation of the columns' nonlinear behavior and was rigorously validated against experimental data. This model aids in the design and implementation of more efficient and resilient urban structures, supporting the principles of sustainable construction. The study underscores the importance of structural integrity in sustainable urban development and provides valuable insights for improving the design of green building materials. [ABSTRACT FROM AUTHOR]

This article investigates the influence of porosity distributions on the nonlinear behavior of two-directional functionally graded porous plates (TDFGPP) made from four distinct materials for the first time. A simple and effectual approach is established based on the improved generalized shear deformation plate theory (GSDPT) and von Karman's assumptions. The GSDPT incorporates transverse shear strains with a higher order polynomial to avoid shear locking. The TDFGPP constitutes four different materials, and the modified power-law function is employed to vary the material properties continuously in both transverse and longitudinal directions. The governing equations are obtained using a nonlinear finite element approach in conjunction with Hamilton's principle. Then, the direct iterative and Newmark's methods are incorporated to accomplish the numerical results. Finally, the influence of volume fraction grading indices, porosity distributions, porosity volume, thickness ratio, and aspect ratio for different support conditions provides a thorough insight into the linear and nonlinear responses of the porous plate. In addition, this study emphasizes the influence of the volume fraction gradation profiles with four different materials on the linear frequency, nonlinear frequency, and deflections of the TDFGPP. The numerical analysis reveals that the frequencies and nonlinear deformations can be significantly regulated by changing the volume fraction gradation profiles in specified directions with appropriate materials. Hence, two-directional functionally graded materials panels can overcome the drawbacks of the functionally graded materials with a gradation of properties in a single direction. [ABSTRACT FROM AUTHOR]

Featured Application: Behavior prediction of channel shear connectors in normal and high-strength concrete (HSC) without conducting costly experiments. Channel shear connectors are known as an appropriate alternative for common shear connectors due to having a lower manufacturing cost and an easier installation process. The behavior of channel connectors is generally determined through conducting experiments. However, these experiments are not only costly but also time-consuming. Moreover, the impact of other parameters cannot be easily seen in the behavior of the connectors. This paper aims to investigate the application of a hybrid artificial neural network–particle swarm optimization (ANN-PSO) model in the behavior prediction of channel connectors embedded in normal and high-strength concrete (HSC). To generate the required data, an experimental project was conducted. Dimensions of the channel connectors and the compressive strength of concrete were adopted as the inputs of the model, and load and slip were predicted as the outputs. To evaluate the ANN-PSO model, an ANN model was also developed and tuned by a backpropagation (BP) learning algorithm. The results of the paper revealed that an ANN model could properly predict the behavior of channel connectors and eliminate the need for conducting costly experiments to some extent. In addition, in this case, the ANN-PSO model showed better performance than the ANN-BP model by resulting in superior performance indices. [ABSTRACT FROM AUTHOR]

Evaluation of the parameters affecting the shear strength and ductility of steel-concrete composite beam is the goal of this study. This study focuses on predicting the future output of beam’s strength and ductility based on relative inputs using a soft computing scheme, extreme learning machine (ELM). Estimation and prediction results of the ELM models were compared with genetic programming (GP) and artificial neural networks (ANNs) models. Referring to the experimental results, as opposed to the GP and ANN methods, the ELM approach enhanced generalization ability and predictive accuracy. Moreover, achieved results indicated that the developed ELM models can be used with confidence for further work on formulating novel model predictive strategy in shear strength and ductility of steel concrete composite. Furthermore, the experimental results indicate that on the whole, the newflanged algorithm creates good generalization presentation. In comparison to the other widely used conventional learning algorithms, the ELM has a much faster learning ability. [ABSTRACT FROM AUTHOR]

Pavements porous concrete is a noble structure design in the urban management development generally enabling water to be permeated within its structure. It has also capable in the same time to cater dynamic loading. During the technology development, the quality and quantity of waste materials have led to a waste disposal crisis. Using recycled materials (secondary) instead of virgin ones (primary) have reduced landfill pressure and extraction demanding. This study has reviewed the waste materials (Recycled crushed glass (RCG), Steel slag, Steel fiber, Tires, Plastics, Recycled asphalt) used in the pavement porous concretes and report their respective mechanical, durability and permeability functions. Waste material usage in the partial cement replacement will cause the concrete production cost to be reduced; also, the concretes' mechanical features have slightly affected to eliminate the disposal waste materials defects and to use cement in Portland cement (PC) production. While the cement has been replaced by different industrial wastes, the compressive strength, flexural strength, split tensile strength and different PC permeability mixes have depended on the waste materials' type applied in PC production. [ABSTRACT FROM AUTHOR]

The behavior of concrete slabs in composite beam with C and L shaped angle shear connectors has been studied in this paper. These two types of angle shear connectors' instalment have been commonly utilized. In this study, the finite element (FE) analysis and soft computing method have been used both to present the shear connectors' push out tests and providing data results used later in soft computing method. The current study has been performed to present the aforementioned shear connectors' behavior based on the variable factors aiming the study of diverse factors' effects on C and L shaped angle in shear connectors. ANFIS (Adaptive Neuro Fuzzy Inference System), has been manipulated in providing the effective parameters in shear strength forecasting by providing input-data comprising: height, length, thickness of shear connectors together with concrete strength and the respective slip of shear connectors. ANFIS has been also used to identify the predominant parameters influencing the shear strength forecast in C and L formed angle shear connectors. [ABSTRACT FROM AUTHOR]

This paper investigates the behaviour of C-shaped and L-shaped angle shear connectors embedded in solid concrete slabs. An effective finite element model is proposed to simulate the push out tests of these shear connectors that encompass nonlinear material behaviour, large displacement and damage plasticity. The finite element models are validated against test results. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength and connector dimensions. The finite element analyses also confirm the test results that increasing the length of shear connector increases their shear strength proportionately. It is observed that the maximum stress in L-shaped angle connectors takes place in the weld attachment to the beam, whereas in the C-shaped angle connectors, it is in the attached leg. The location of maximum concrete compressive damage is rendered in each case. Finally, a new equation for prediction of the shear capacity of C-shaped angle connectors is proposed. [ABSTRACT FROM AUTHOR]

According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. [ABSTRACT FROM AUTHOR]

Steel pallet rack (SPR) beam-to-column connections (BCCs) are largely responsible to avoid the sway failure of frames in the down-aisle direction. The overall geometry of beam end connectors commercially used in SPR BCCs is different and does not allow a generalized analytic approach for all types of beam end connectors; however, identifying the effects of the configuration, profile and sizes of the connection components could be the suitable approach for the practical design engineers in order to predict the generalized behavior of any SPR BCC. This paper describes the experimental behavior of SPR BCCs tested using a double cantilever test set-up. Eight sets of specimens were identified based on the variation in column thickness, beam depth and number of tabs in the beam end connector in order to investigate the most influential factors affecting the connection performance. Four tests were repeatedly performed for each set to bring uniformity to the results taking the total number of tests to thirty-two. The moment-rotation (M-θ) behavior, load-strain relationship, major failure modes and the influence of selected parameters on connection performance were investigated. A comparative study to calculate the connection stiffness was carried out using the initial stiffness method, the slope to half-ultimate moment method and the equal area method. In order to find out the more appropriate method, the mean stiffness of all the tested connections and the variance in values of mean stiffness according to all three methods were calculated. The calculation of connection stiffness by means of the initial stiffness method is considered to overestimate the values when compared to the other two methods. The equal area method provided more consistent values of stiffness and lowest variance in the data set as compared to the other two methods. [ABSTRACT FROM AUTHOR]

In this paper, an Adaptive nerou-based inference system (ANFIS) is being used for the prediction of shear strength of high strength concrete (HSC) beams without stirrups. The input parameters comprise of tensile reinforcement ratio, concrete compressive strength and shear span to depth ratio. Additionally, 122 experimental datasets were extracted from the literature review on the HSC beams with some comparable cross sectional dimensions and loading conditions. A comparative analysis has been carried out on the predicted shear strength of HSC beams without stirrups via the ANFIS method with those from the CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94 codes of design. The shear strength prediction with ANFIS is discovered to be superior to CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94. The predictions obtained from the ANFIS are harmonious with the test results not accounting for the shear span to depth ratio, tensile reinforcement ratio and concrete compressive strength; the data of the average, variance, correlation coefficient and coefficient of variation (CV) of the ratio between the shear strength predicted using the ANFIS method and the real shear strength are 0.995, 0.014, 0.969 and 11.97%, respectively. Taking a look at the CV index, the shear strength prediction shows better in nonlinear iterations such as the ANFIS for shear strength prediction of HSC beams without stirrups. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ductility performance for angle shear connectors in HSC was inadequate. [•] A small amount of fatigue energy dissipation under fatigue loading was detected. [•] All push-out specimens experienced connector fracture failure subjected to monotonic and fatigue loading. [Copyright &y& Elsevier]

Highlights: [•] Required ductility was not achieved for angle shear connectors embedded in HSC. [•] Angle connectors in HSC under low cyclic loading showed very low strength degradation (0.1%–1.4%). [•] Angle connectors embedded in HSC, experienced angle fracture type of failure in both static and cyclic loading. [•] The current equations estimated the shear capacity of angle connectors in HSC either are conservative or overestimate. [Copyright &y& Elsevier]

Abstract: Channel shear connectors are used to transfer longitudinal shear forces through the steel–concrete interface in composite beams. Angle shear connectors without bottom flange compared to channel shear connectors could be cheaper and more economic by saving more steel material. This paper presents an experimental evaluation for comparison of the behaviour of channel and angel shear connectors under monotonic and fully reserved cyclic loading based on 16 push-out tests. The connection shear resistance, ductility and failure modes are presented and discussed. By comparing the channel and angle shear connectors, it was concluded that angle shear connectors showed 7.5–36.4% less shear strength than channel shear connectors under monotonic loading and 23.6–49.2% under fully reversed cyclic loading. Connector’s fracture type of failure was experienced for both channel and angle connectors. After the failure, more cracking was observed in slabs with channels compared to slabs with angles. Furthermore, in despite of sufficient ductility for all channel connectors, angle connectors showed less ductility. The results indicate that the angle shear connector gave good behaviour in terms of the ultimate shear capacity; however, this type of connector cannot satisfy the ductility criteria imposed by some codes. In the end, the shear load capacities obtained from the experiments are compared with those suggested by the design codes. [Copyright &y& Elsevier]

Steel-Concrete Composite floor systems are one of the essential components in the construction industry. Recent studies have shown that fire-induced problems damage shear connectors and change the behavior of composite systems. To predict the performance of connectors, experimental tests are generally conducted at elevated temperatures or fire conditions. However, these tests need plenty of time, cost, and effort. This paper aims to propose a soft computing (SC) approach to predict the behavior of angle shear connectors at elevated temperatures. For this purpose, an adaptive neuro-fuzzy inference system (ANFIS), a particle swarm optimization (PSO) algorithm, and a genetic algorithm (GA) are hybridized and a novel ANFIS-PSO-GA model is proposed. To evaluate the performance of the ANFIS-PSO-GA model, a radial basis function network (RBFN) along with an extreme learning machine (ELM) are also developed. Finally, the performance of the ANFIS-PSO-GA, RBFN, and ELM are compared in the terms of different statistical indicators. The results of the paper show that the SC approach is applicable in the behavior prediction of angle connectors at elevated temperatures. Besides, it was concluded that the ANFIS-PSO-GA model can provide better estimations of load and slip in comparison with those of RBFN and ELM models. [ABSTRACT FROM AUTHOR]

• Effect of pumice powder and nano-clay as Portland cement replacement is investigated. • Pervious concrete with different percentages of recycled concrete aggregate (RCA) is produced. • Industrial and recycled fibers are incorporated in pervious concrete mixes. • Mix containing 50% pumice powder and 100% RCA meets the strength and permeability requirements of pervious concrete. • Pervious concrete with 50% RCA and 2% steel fiber can be used for structural application. Pervious concrete (PC) has been widely used to construct concrete pavements and to increase the permeable surfaces all over the world. With the boost in the use of PC, it is necessary to make it more environmental-friendly and cost efficient. This study investigates employing recycled concrete aggregate (RCA) and pozzolanic additives as a partial replacement (PR) of natural coarse aggregate (NCA) and Portland cement, respectively. For this purpose, the NCA was replaced with 10%, 25%, 50% and 100% RCA and the Portland cement was replaced with 10%, 25% and 50% pumice used in combination with 1–3% nano-clay (NC). The compressive and flexural strengths, void content, density, and permeability of concrete were evaluated. Moreover, the effect of adding three different types of fibers including steel fiber (STF), macro-fiber (MF), and waste plastic fiber (WPF) at volume fractions of 1% and 2% on the properties of concrete was studied. A total number of 7791 specimens from 371 mixtures were cast and tested. Using RCA decreased density, compressive strength (CS) (up to 58%) and flexural strength (FS) (up to 64%) and increased the void content and permeability (up to 15%) of concrete. The use of pumice generally reduced the early-age strength of concrete; however, using 10–25% pumice increased the mechanical strength at 90 days. Incorporating 1–3% NC also had positive effects on the strength properties and led to a minor reduction in permeability. STF performed better than MF and WPF, and adding 1% STF, MF, and WPF increased the 180-day FS of RC25 by 78.9%, 67.4% and 37.1%, respectively. The effectiveness of fibers declined with the increase in RCA content, which could be related to the poor compaction of concrete. According to the test results, the 90-day CS of mix RC50Pu25 with 2% STF and mix RC100Pu10NC1 was equal to the control mix. Therefore, it sounds that it is a feasible approach to significantly reduce the consumption of NCA and cement by using specific dosages of the other materials used in this study. [ABSTRACT FROM AUTHOR]

Urbanization and population growth have resulted in a significant increase in the amount of generated construction and demolition (C&D) waste worldwide. Improper C&D waste management has led to a tremendous landfilled C&D waste, which has placed a great concern over its adverse impacts on the environment and natural resources. Appropriate C&D waste recycling mechanism as a remedial action saves our resources from deterioration, which can be guaranteed through a systematic apportion of the construction projects to C&D waste recycling facilities. Previous studies in waste collection routing problem have almost exclusively assumed that parameters are deterministic; however, uncertainty associated with waste collection routing makes deterministic models inapplicable to real-life systems. To tackle this problem, this research proposes a novel simheuristic based on an integrated simulation-optimization approach, in which an efficient hybrid Genetic Algorithm (GA) is applied in order to optimize vehicle route planning for C&D waste collection from construction projects to recycling facilities. A comparative analysis with existing well-known approaches is performed to represent the strength and effectiveness of the proposed approach. The results demonstrate high performance of the proposed simheuristic algorithm. This study has also benefited from a real case of construction projects apportion to recycling facilities in Sydney, Australia for better evaluation. This research strongly contributes to academics by lighting up the ways to optimize future waste collection problems in a wider range and more precise manner. Meanwhile, this study recommends to C&D waste decision makers and practitioners to allocate generated C&D waste to recycling facilities precisely with respect to the capacity of produced C&D waste, capacity of recycling facilities, distances, and vehicle capacities. [ABSTRACT FROM AUTHOR]