Behavior Of Walls Research Articles

CFRP-strengthened shear walls: Combined effects of CFRP and reinforcement ratio

This study presents a three-dimensional numerical model based on the Hashin damage criteria to assess the seismic performance of Carbon Fiber Reinforced Polymer (CFRP)-strengthened Reinforced Concrete (RC) shear walls, accurately capturing the rupture of CFRP strips. The effectiveness of various CFRP-concrete interface modeling methods in capturing CFRP debonding was initially discussed. A series of numerical simulations were then conducted to investigate the combined effects of the CFRP ratio and the horizontal reinforcement ratio on the seismic behavior of CFRP-strengthened shear walls. The results indicate that an increase in the CFRP ratio reduces the failure degree of shear walls, as the shear damage shifts progressively from the concrete and horizontal reinforcement to the CFRP strips. However, an increase in the horizontal reinforcement ratio counterproductively weakens the shear-strengthening effect provided by the CFRP strips. To specifically evaluate the shear contribution of the CFRP strips, a novel coefficient was proposed and validated, capturing the combined effect of the CFRP ratio and the horizontal reinforcement ratio on the shear contribution of the CFRP strips. This coefficient provides a quantitative measure to optimize the reinforcement design of RC shear walls.

Soil structure interaction studies on earth retaining wall

Abstract The paper offers a brand-new analytical technique for figuring out retaining wall natural frequencies, which are essential for seismic design. Using translational and torsion springs to account for soil-backfill interaction and foundation flexibility, the approach applies the theory of beams on elastic foundations. There are three closed-form techniques offered for figuring out the natural frequencies of flexural and stiff modes. The analytical model takes into account several kinds of retaining walls and the interactions between soil and structure that go along with them, such as active, passive, and dynamic earth pressures. To make the analysis simpler, certain assumptions are made about the behaviour of the structure and the state of the soil. The suggested technique provides a trustworthy means of assessing retaining wall behaviour during seismic events, which is crucial for guaranteeing structural stability and averting failure.

Seismic behavior of a hollow precast concrete shear wall with insulation under high axial compression ratios

A hollow precast concrete shear wall (HPCSW) with multiple vertical hollow cores that is advanced in lightweight and thermal insulation is studied in this paper. Novel tapered grouted sleeves (TGSs) are developed to connect the adjacent shear walls, which can avoid grouting defects through visible grouting processes. Seven full-size specimens with an aspect ratio of 3.3, including three solid precast shear walls, three hollow precast shear walls, and a cast-in-place (CIP) shear wall, were subjected to cyclic loading tests, which considered different and high axial compression ratios (ACRs) of 0.3, 0.45, and 0.6. The results show that the solid precast shear wall with the TGS connection displays comparable failure mode and seismic behavior with the CIP one. In contrast, the HPCSW suffers hollow core crushing under high ACRs, leading to a significant reduction in deformation and energy dissipation capacity. Finally, numerical models of HPCSW specimens with different layouts of the hollow cores were established using ABAQUS to evidence the test results and optimize the structure. The results show that the configuration of the outer hollow cores influences the seismic behavior of the HPCSW vastly. It is recommended that the concrete is partially filled into the outer hollow cores to obtain good insulation and seismic capacity simultaneously, with the filling height greater than the predicted crushing height.

Behaviour of a Cold-Formed Steel Shear Wall with Centre-Corrugated Steel Sheathing under Cyclic Loading

A cold-formed steel shear wall with centre-corrugated steel sheathing (CCSS-CFS shear wall) was innovatively developed to meet the requirement of earthquake resistance for multi-rise CFS structures in regions at high seismic risk. This wall exhibits superior seismic performance in comparison with the conventional CFS shear wall. Five full-size specimens were tested under cyclic loading to evaluate their failure mode, shear strength, lateral stiffness, ductility, energy dissipation, as well as degradation of bearing capacity and stiffness. Additionally, the effects of CFS frame structure forms, screw spacing, and corrugated steel sheet thicknesses on the behaviour and failure mechanism of shear walls were analysed. The seismic performance objectives corresponding to intact, slight, moderate, and severe damage were also determined. The results revealed that the main failure modes of shear walls were plastic buckling of corrugated steel sheathing and local buckling of the end composite stud. Optimising configurations such as setting up stiffening plates on the end composite stud, installing transverse braces, and increasing screw spacing between composite studs and sheathing significantly improved their behaviour. The strength of corrugated steel sheathing after plastic buckling should be taken into consideration for the lateral design of the CCSS-CFS shear wall. A calculation method was also proposed in order to determine the elastic global buckling shear strength of the CCSS-CFS shear wall – which exhibited high accuracy. Finally, nominal shear strength, a resistance factor, and a safety factor were recommended.

Identifying failure connection area on wall for deep excavation based on system stiffness influence factor

In this study, a methodology to identify weak or failure connection area on the wall of deep excavation was proposed based on the system stiffness influence factor (IF), which can be beneficially utilized for wall-collapse prevention and forecasting system. Irregular excavation configuration common in urban areas and various weak-connection locations were considered. Three-dimensional finite element analyses with full consideration of actual staged excavation and strut-waler connection condition were performed. It was found that wall deflection and ground movement increased as the location of weak connection became deeper. It was also found that the influence of weak connection on the wall behavior became more pronounced as it located towards the center of the wall. The effects of weak connection on wall deflection were evaluated and quantified using IF. A modification procedure for IF was introduced to consider the effects of depth and horizontal weak-connection locations. The modified IF was adopted to establish a method for quantifying and identifying weak or failure connection area on the wall based on measured wall deflection from field monitoring. Case examples were selected to check the validity of the proposed method. The compared results showed that monitored and predicted locations of weak connection were in close agreement.

Study on Seismic Behavior and Component Vulnerability of Corroded RC Shear Walls Subjected to Flexural Shear Failure

ABSTRACT The impact of corrosion degree, axial compression ratio, reinforcement ratio of longitudinal bar and horizontal distribution rebar, and stirrup of boundary column on seismic performance of RC shear walls were investigated. The corrosion forms (rust expansion cracks and corroded steel bars), failure process, hysteretic characteristics, bearing capacity, and deformability were compared. Subsequently, a numerical model of corroded RC shear walls was established adopting shell elements. Finally, according to the numerical simulation method, considering the uncertainty of corrosion degree and material parameters, the vulnerability models of RC shear wall components with different corrosion degrees were built. The results show that the mechanical properties of the shear wall were seriously deteriorated due to the corrosion of steel bars, and the ultimate displacement and ductility coefficient of severely corroded specimens were reduced by 28.5% and 12.27% respectively, compared to non-corroded specimens. A proposed numerical modeling method for corroded RC shear walls based on shell element is accurate, and the bearing capacity error and energy dissipation error of the simulation and test results were less than 20%. As the degree of corrosion grew, the probability of shear wall components experiencing more severe failure added significantly. When the displacement angle was 1/120 (This is the limit value of elastic-plastic displacement angle specified in the code), the probability of DS3 and DS4 occurring in the shear wall with a corrosion degree of 0% were 56% and 39.44%, and the probability of DS4 and DS5 occurring in the shear wall with a corrosion degree of 10% were 41.1% and 38.44%.

Evaluation of interactional behavior of suspended ceilings and partition walls through shake table tests

Earthquakes cause seismic losses due to direct and indirect effects of damage to structural and nonstructural elements in buildings. Suspended ceiling-to-partition wall (SCPW) systems, the most earthquake-vulnerable nonstructural elements, may suffer severe damage under earthquakes even with low and moderate intensities. However, there is still limited research on investigating the seismic performance of SCPW systems in buildings located at low- or moderate-seismicity regions. This study aims to experimentally evaluate the seismic response of SCPW systems using shake-table test program and to deeply investigate the interaction between a partition wall and a ceiling. To do this, the shake table program was carried out using a full-scale specimen employing SCPW systems and its results were summarized and analyzed. The frequencies measured at the partitions were similar to those measured at the test frame whereas the fundamental frequency of the suspended ceiling was decoupled to the floor acceleration of the test frame. The full-height partitions presented relatively good seismic response because of the sufficient lateral support at the top of the partition, whereas severe damage was mainly concentrated on the ceiling elements due to pounding effects. The partial-height partitions with improper anchor detailing to adjacent suspended ceiling suffered severe damage. Such poor seismic performance is because they suffer pounding effects resulting from the interactional behavior which are magnified in partition walls with lack of sufficient lateral supporting. Both partial-height partitions and ceiling elements were seriously damaged.

Thermo-Mechanical Behaviour of a New SIP Wall Under Axially Compressive Load

Thermo-Mechanical Behaviour of a New SIP Wall Under Axially Compressive Load

Experimental and numerical investigation on seismic performance of SFRC shear walls with CFRP bars

In order to investigate the seismic performance of steel fiber reinforced concrete (SFRC) shear walls with CFRP bars, quasi-static tests were conducted on six full-scale shear walls with a shear span ratio of 2.0, including one steel bars reinforced ordinary concrete (RC) shear wall, one CFRP bars reinforced ordinary concrete (CRC) shear wall and four CFRP bars reinforced SFRC (CSFRC) shear walls. The variables included steel fiber volume fraction (SFVF), axial load ratio and concrete strength grade. The experimental results showed increasing the SFVF could significantly decrease the concrete damage level and improve repairability. Meanwhile, the bearing capacity, ductility, and energy dissipation capacity all improved, and the stiffness degradation slowed. Compared to RC shear wall, the peak load of the CSFRC shear wall with SFVFs of 0 %, 0.75 % and 1.5 % increased by 16.36 %, 30.06 % and 46.01 %, respectively. The residual drift ratio decreased by 54.75 %, 61.61 %, and 52.98 % at 2.2 % drift ratio, respectively. Compared to CRC shear wall, the cumulative energy dissipation of the CSFRC shear wall with SFVFs of 0.75 % and 1.5 % increased by 39.54 % and 94.10 %; and the ductility increased by 5.12 % and 18.06 %, respectively. These improvements indicated that applying SFRC with SFVFs of 0.75 % and 1.5 % to shear walls reinforced with CFRP bars could effectively improve the seismic performance and compensate for the shortcomings of resilient shear walls. In addition, increasing the axial load ratio improved the bearing capacity, but decreased deformation capacity and accelerated stiffness degradation. An increase in concrete strength significantly improved the bearing capacity, stiffness and energy dissipation but reduced ductility. Meanwhile, the stability of lateral loads at large drift ratios weakened. Additionally, a detailed finite element model (FEM) was established using DIANA and the accuracy was verified by comparing the simulation and experimental results. Subsequently, parametric analyses were carried out to study the effects of shear span ratio, CFRP bar ratio, and wall thickness on the seismic behaviour of CSFRC shear walls.

Behavior of steel plate shear walls reinforced with stiffened FRP plates

Steel plate shear walls require retrofitting due to factors such as corrosion, long–term loading and functional changes. In an effort to modernise the technology used for strengthening and retrofitting steel plate shear walls, fibre–reinforced polymer (FRP) plates with additional stiffeners are employed to enhance the shear capacity of steel structures. In this study, the static properties of steel plates reinforced with these stiffened FRP plates were experimentally investigated. The application of this strengthening methodology substantially enhanced the out–of–plane stability, shear stiffness and bearing capacity of the plates, while also reducing fatigue damage. Equations for estimating the buckling and ultimate load of steel plates reinforced with stiffened FRP plates have been derived, enabling predictions of their practical performance. Finite element models incorporating the potential failure of epoxy at the FRP–steel interface were developed for further analysis. A numerical study was performed to investigate the optimal thickness of the FRP stiffener. The analysis revealed that stiffener thicknesses exceeding 6 mm did not significantly contribute to the enhancement of the load–bearing capacity or to the prevention of debonding. When the FRP rib thickness exceeds 6 mm, the economy was poor. The aforementioned findings are of considerable engineering importance, especially in the context of improving fatigue properties and shear load–bearing capacity of thin steel plates.

Cyclic Behavior of Partially Prefabricated Steel Shape-Reinforced Concrete Composite Shear Walls: Experiments and Finite Element Analysis

Due to the higher lateral stiffness, load-carrying, and energy dissipation capacities compared with traditional reinforced concrete (R.C.) shear walls, steel shape-reinforced concrete (SRC) shear walls, in which steel profiles are encased in the boundary elements, have been widely applied in high-rise buildings. In order to simplify the on-site construction procedure, this paper proposes a novel partially prefabricated steel shape-reinforced concrete (PPSRC) shear wall using throat connectors. Based on the pseudo-static tests of two large-scale specimens, the effect of construction methods (prefabricated or cast in place) on the cyclic behavior of PPSRC shear walls was investigated by the hysteretic loops, skeleton curves, stiffness degradation, energy dissipation, and deformation decomposition. The test results indicated that PPSRC shear walls could exhibit a comparative cyclic response with the cast-in-place SRC shear walls, and the proposed throat connectors could effectively transfer the stress of the longitudinal reinforcements. Finally, a macro-modeling of PPSRC shear walls based on the multi-layer shell elements in OpenSees 3.3.0 was established and validated by the test results, and the parametric analysis of the axial compression, steel ratio, and concrete strength of prefabricated and cast-in-place parts was then conducted.

Behaviour of sheet pile wall on sloping ground for strip footing as surcharge with coir geotextile reinforced backfill soil

Behaviour of sheet pile wall on sloping ground for strip footing as surcharge with coir geotextile reinforced backfill soil

Structural Performance of Ferrocement Hollow Shear Walls Subjected to Lateral and Compressive Axial Loads

In this study, ten shear walls were experimentally tested to examine behaviour of ferrocement hollow shear walls subjected to axial and lateral loads. Ferrocement mortar (FM) was used to build eight walls, while normal concrete (NC) was used to build two controls. Walls were lateral reinforced using conventional stirrups, two layers of welded wire mesh (WWM), and expanded steel mesh (ESM). Two specimens lacked lateral reinforcement except for one transverse web in the center of the inner hole. Two symmetric groups of five walls each were created by dividing the walls. While the other group was loaded laterally, one group was loaded axially. In each group, the load–displacement relationship, maximum load and associated displacement, stiffness, ductility, and failure mechanism of FM and NC walls were compared. The results showed that FM walls provided with ESM and WWM had ultimate axial loads that were, respectively, 36% and 19% higher than NC control walls. Ultimate lateral loads and related ultimate drifts of FM walls reinforced with two layers of WWM and ESM were, respectively, 68% and 39%, 96% and 43.5%, larger than control NC wall. For lateral loads greater than those applied to the NC control wall, stiffness increase ratios for FM walls ranged from 2.5% to 89.5%, and for axial loads, they ranged from 20% to 150.5%. The ductility of FM walls increased when compared to NC walls by 58.5% and 158.8% for axial and lateral loading, respectively, when two layers of WWM were utilized to lateral reinforce FM walls. When two layers of ESM were applied to laterally reinforce FM walls in comparison to an NC wall, this increased the walls' ductility under axial and lateral loads by 110.5% and 214.7%, respectively.

Conjugate heat transfer analysis of developing region of square ducts for isothermal and isoflux boundary conditions

Purpose This paper aims to present a comprehensive analysis of conjugate heat transfer phenomena occurring within the developing region of square ducts under both isothermal and isoflux boundary conditions. The study involves a rigorous numerical investigation, using advanced computational methods to simulate the complex heat exchange interactions between solid structures and surrounding fluid flows. The results of this analysis provide valuable insights into the heat transfer characteristics of such systems and contribute to a deeper understanding of fluid–thermal interactions in duct flows. Design/methodology/approach The manuscript outlines a detailed numerical methodology, combining computational fluid dynamics and finite element analysis, to accurately model the conjugate heat transfer process. This approach ensures both the thermal behaviour of the solid walls and the fluid flow dynamics are well captured. Findings The results presented in the manuscript reveal significant variations in heat transfer characteristics for isothermal and isoflux boundary conditions. These findings have implications for optimizing heat exchangers and enhancing thermal performance in various engineering applications. Practical implications The insights gained from this study have the potential to influence the design and optimization of heat exchange systems, contributing to advancements in energy efficiency and engineering practices. Originality/value The research introduces a novel approach to study conjugate heat transfer in square ducts, particularly focusing on the developing region. This unique perspective offers fresh insights into heat transfer mechanisms that were previously not thoroughly explored.

A Constitutive Framework for Modeling of the Visco-Hyperelastic Materials: Application to the Mechanical Behavior of Cylinders Made of the Rate-Dependent Elastomers

In this paper, the formulation of the mechanical behavior of visco-hyperelastic materials is developed in a thermo-dynamically compatible framework. In this viewpoint, the stress power is assumed to be equal to the sum of the reversible (elastic) energy rate stored and the irreversible energy rate dissipated. Based on this assumption and using the second law of thermodynamics, the constitutive modeling framework is obtained for the rate-dependent materials. Inspired by the constitutive law of a Newtonian fluid and also, models of density strain energy of an elastic material, a framework for the dissipative energy rate related to the irreversible part is proposed for viscoelastic materials. In this framework, the reversible energy part is considered a function of the right Cauchy–Green deformation tensor, and the irreversible energy part is considered a function of the same tensor’s rate. To evaluate the proposed model for nonlinear viscoelastic behavior modeling, the results of tests performed on non-compressible materials at different rates are used, and the proposed model provided acceptable results. Finally, the proposed model is implemented to find a closed-form analytical solution for mechanical behavior modeling of the thick-walled cylindrical shells made of visco-hyperelastic materials, also, stress and stability analyses are assessed for these types of cylinders. To achieve this goal, the effect of pre-stretch on the stability of cylinders has been substantially investigated. Furthermore, based on the proposed model, the effect of the parameters such as the wall thickness and behavior of the material used in the cylinder are examined on the stability of open-ended and closed-ended cylinders.

Estimate the impact of deep excavation construction in high-rise buildings on neighboring structures

The estimation of diaphragm wall displacements and soil movement around the deep excavation of a high-rise building during the construction of basement floors plays a crucial role in limiting risks that may cause damages to human lives and property during the construction process. This study proposes the use of Finite Element Analysis (FEA) to accurately predict the behavior of soil and diaphragm walls in deep excavations of high-rise buildings. The model is based on advanced soil models and considers the interaction between diaphragm walls and soil, enabling the prediction of adverse impacts during the construction process, as well as negative effects on adjacent buildings. Additionally, the study will analyze and highlight the primary parameters that negatively impact the excavation process and neighboring constructions.

Cyclic behaviour of Glulam, LVL and GLVL shear walls and their base connections

This paper presents an experimental study aimed at characterizing the lateral cyclic behaviour of Glulam (GL), Laminated Veneer Lumber (LVL), and Glued Laminated Veneer Lumber (GLVL) shear walls anchored to the foundation by means of conventional hold downs and angle brackets, which are fastened to the timber walls with annular ring nails. Monotonic and cyclic tests are conducted on these mechanical anchors, with hold down connections tested under tensile loads and angle bracket connections under shear loads. Withdrawal tests on annular ring nails embedded in GL, LVL, and GLVL elements are also conducted, to investigate the withdrawal response of the fasteners. The experimental tests reveal that the lateral behaviour of GL, LVL, and GLVL shear walls is similar to that of Cross-Laminated Timber (CLT) shear walls, primarily governed by the wall base connections and by the wall geometry. Hold down and angle bracket connections exhibited a mechanical behaviour governed by the steel-to-timber joints, to large extent comparable with that of typical hold downs and angle brackets fastened to CLT elements. Generally, higher ductility and lower load carrying capacity were reached by hold downs and angle brackets fastened to GL elements compared to those reached by hold downs and angle brackets fastened to LVL and GLVL elements. All quantities relevant for the seismic design, such as stiffness, load carrying capacity, ductility, and overstrength factors are calculated and discussed through the paper. These quantities are then compared with results from different experimental investigations on hold downs and angle brackets fastened to CLT elements available in the literature. Finally, an analytical model for the calculation of the lateral load carrying capacity of the shear walls is presented and used to verify that the same calculation models used for CLT shear walls can be adopted for GL, LVL, and GLVL shear walls.

Study on the Shear Behaviors and Capacity of Double-Sided Concrete-Encased Composite Steel Plate Shear Walls by Experiment and Finite Element Analysis

Concrete-encased composite plate shear walls (C-PSW/CEs) can realize the in-plane shear yielding of infill steel plate with the buckling restrained from the concrete panel. Concrete panels also additionally resist portions of lateral loading in C-PSW/CEs, whereby the shear stiffness and strength of the C-PSW/CE are improved. However, research on the in-plane behaviors of concrete panels and the interactions between structural elements is limited. In this paper, the mechanical characteristics and the interactions and the shear resistances of C-PSW/CEs with double-sided concrete encasements were studied. First, the effects of concrete thickness on the damage process, steel plate buckling, and shear resistances of C-PSW/CEs under lateral loading were tested. Then, finite element analyses of the internal forces of the horizontal and inclined cross-sections and the shear force–drift ratio responses of C-PSW/CEs were undertaken with the extended finite element method (XFEM) to simulate the cracking behaviors of concrete panels. A shear force–drift ratio model based on mechanics was developed by considering the lateral load resistances of concrete panels and their effects on steel plates in C-PSW/CEs.

Strength calculation method and numerical simulation of slender concrete shear walls with CFRP grid-steel reinforcement

A series of experimental research has demonstrated superior hysteretic behavior, damage mitigation, and self-centering properties of concrete shear walls incorporating CFRP grid-steel reinforcement. Developing comprehensive theoretical and numerical models becomes crucial to assess the performance of these novel walls for structural design and application purposes. Based on the preliminary experimental investigation, a strength calculation method and numerical model for slender concrete shear walls with CFRP grid-steel reinforcement were proposed in this study. The calculation method provided a stable estimation for the loading capacity and ultimate compressive strain of edge concrete for the slender CFRP grid shear wall. The fracture strain of outermost longitudinal CFRP grid and ultimate compressive strain of edge concrete were suggested for design. The numerical model integrated hybrid reinforcements and utilized MVLEM to simulate the nonlinear hysteretic behavior of CFRP grid shear walls, effectively considering specimen failure mechanisms. The model can well capture the hysteretic behavior of the specimen, involving the peak loading, envelope curve, residual deformation, and stiffness degradation. Finally, the parametric analysis was conducted to further investigate the effects of axial compressive ratio and aspect ratio on shear walls with CFRP grid-steel reinforcement.

Experimental shear behaviour of masonry walls reinforced with FRCM

The shear strength of piers and spandrels is a crucial factor in masonry buildings, affecting structural safety. Such a strength can be increased in several ways, particularly by using fiber reinforced cementitious matrix (FRCM) reinforcements. These reinforcements can be applied symmetrically on both sides of the wall or only on one side. As it is well known, the FRCM-to-substrate adhesive properties strongly affect the effectiveness of such reinforcements. Moreover, a complete covering of the reinforced surface with bidirectional mesh evenly distributes the stresses, improving the load-bearing capacity. Appropriate test methods, for example diagonal tests, can be effectively used to evaluate the shear capacity of masonry panels, even with externally bonded composite material reinforcements, and the corresponding failure mechanism. This paper describes the results of an experimental campaign involving masonry panels, made with three different types of mortar, also reinforced with a PBO-FRCM system, subjected to diagonal tests. Through the experimental results, it was possible to determine the shear capacity of the panels, identify the failure mechanisms and evaluate the effectiveness of the FRCM reinforcements. The predictive capability of design formulas proposed in the literature for evaluating the shear capacity of unreinforced and reinforced masonry panels has been analyzed in the paper.