A drift-based design procedure for RC buildings considering the effect of shear wall-floor slabs junction

The natural vibration characteristics of a structure play a significant role in estimation of seismic behaviour of a structure. The principal natural vibration characteristic, namely the natural period of vibration, is experimentally estimated by either carrying out ambient vibration studies or from the observed seismic behaviour of the building. The design guidelines of different countries also provide some estimate of the natural period by prescribing empirical expressions. Reinforced Concrete (RC) frame buildings with structural walls are commonly prescribed for highrise buildings in regions of strong earthquake shaking. Currently, the Indian Earthquake Code IS:1893 (Part 1): 2002 does not prescribe any expression for estimation of natural period of an RC frame building with structural wall. The present study is intended to prescribe such an expression based on parametric studies of structural walls in RC frame buildings. In the current study, a symmetrical plan RC frame building is modeled in the computer program SAP2000. The beams and columns have been modeled as frame elements and the slabs and shear walls have been modeled as shell elements. The building is assumed to be founded on rocky stratum with the restraint of all translational and rotational degrees of freedom of the nodes at the bottom of the columns. The investigations were carried out varying three parameters of the structural wall, namely (a) height, (b) modulus of elasticity of concrete, and (c) thickness. Modal analysis was carried out for each building model for obtaining the fundamental natural period of vibration. Based on the regression analysis of the results of parametric studies, an expression is proposed for obtaining the fundamental period of vibration of RC frame buildings with structural walls.

Reinforced Concrete (RC) structural walls are commonly used in tall RC frame–wall buildings in severe seismic zones for enhancing lateral strength and stiffness of the buildings. Conventionally, the structural walls in multi-storeyed buildings are designed in the same way as isolated shear walls. However, due to the presence of floor slabs at different levels, there is an increase of stiffness locally at each slab–wall junction, which may lead to a significantly different response of the assemblage as compared to the isolated shear wall. Also, the floor slabs tend to partition the slender wall into a number of smaller panels between successive floor slabs. The present study aims to investigate the seismic behaviour of such multi-storeyed slab–wall assemblage using non-linear time history analyses of three different models under ground motions recorded during a past earthquake.

Efficient seismic analysis of high-rise building structures with the effects of floor slabs

Extensive research has been carried out in the past on the behaviour of shear walls for earthquake loading. The junction region of reinforced concrete (RC) wall and floor slab in multistoried buildings plays an important role in transfer of forces to the wall during earthquake shaking. However, extensive investigations on seismic behaviour of structural wall–slab assemblage have not been carried out. In the current study, the possible seismic response of an exterior shear wall–slab junction is investigated through nonlinear static and dynamic analyses of RC wall–slab assemblage. The stresses developed in the wall–slab junction are monitored to investigate the tensile damage. Nonlinear static analysis showed higher values of stresses and tensile damage at the junction region than the dynamic analyses under the selected ground motions.

For construction of reinforced concrete buildings over four stories, structural walls are the predominant form for lateral load resistance under earthquakes. Current Indian seismic code for design of frame shear wall buildings (FSWB) do not explicitly consider the forces transferred from the floor slabs to the shear wall for seismic design. To assess stress concentration at the wall-slab junction region of the building and to observe the extent of possible damages in wall, slab and their junction region, nonlinear static analyses is carried out using ABAQUS program. Further, a wall-slab sub-assemblage is also analyzed to stimulate the observed behavior of the walls in the multistoried buildings and the behavior is compared with the isolated cantilever shear wall. The main intention of the study carried out is to study the behavior of the junction region between the shear wall and the floor slab and to develop a simplified but efficient analytical model to analyse a shear wall - floor slab junction. It is observed that the presence of floor slab at different levels along the height of slender shear wall tends to partition the wall into squat wall panels between two consecutive floors. Thus, an overall seismic design methodology for damage avoidance behavior of floor slabs in multistoried RC frame-wall building needs to be evolved.

Structural robustness evaluation of steel frame buildings with different composite slabs using reduced-order modeling strategies

Reinforced Concrete (RC) structural wall is widely used in multistoried RC frame buildings to enhance lateral stiffness and lateral strength for earthquake resistance. One of the possible failure modes, observed during strong earthquake shaking, is the buckling of longitudinal steel reinforcement in the boundary elements of the wall. This also assumes importance in establishing damage states for seismic fragility analysis of RC wall. Although a few past studies have focussed on longitudinal bar buckling in RC members, detailed parametric study is absent particularly for such instability of bars in the boundary elements of the wall. In the present study, displacement-controlled nonlinear static analysis of several wall specimens is carried out using fibre-discretization of cross-section and distributed plasticity modelling in OpenSEES. Here, 27 different models of the isolated slender wall are created considering variations in six structural parameters, namely (a) length ratio of the boundary element to the wall, (b) axial force ratio, ratios of (c) longitudinal steel in web, and (d) transverse steel and (e) longitudinal steel in the boundary elements. The effect of wall thickness is accounted for through variation in axial force ratio. Using the analytical results from the nonlinear analysis of the wall models, the trends in drift ratio at the onset of longitudinal bar buckling damage states as functions of various key structural wall properties, has been investigated.

Material Quantities of Reinforced Masonry versus Reinforced Concrete Shear Walls

The Open Ground Story (OGS) building is a functional need of all urban areas so cannot be eliminated. According to studies from previous earthquakes, when there is severe earthquake shaking, Reinforced Concrete (RC) frame buildings with open ground levels function badly. In this work, four models of G+14 RC frame buildings with and without a shear wall, coupled sheal wall, and diagonal strut were modeled and analyzed using ETABS-2018 software's static and dynamic response spectrum method. Model 1 open ground story RC building without strut and the shear wall was compared to the other three models that included a shear wall, coupled shear wall, and diagonal strut. As a result of the findings, it has been determined that shear wall, coupled shear wall, and diagonal strut not only increased the stiffness but also reduced displacement. A model with a combination of shear wall and coupled shear wall showed a minimum base shear and overturning moment than all other models.

Reinforced concrete (RC) shear walls are considered as one of the main lateral load resisting structural members in RC buildings. Apart from acting as a lateral load resisting system, the RC shear walls tend to provide ductility, stability and stiffness to the structure. In the present work, an analysis is carried out to assess the residual response of a fire-exposed reinforced concrete structure, by considering the presence of RC shear walls contributing toward the stability of such a structure exposed to fire. The analysis carried out in the present work includes the study of the stability of a multi-storeyed RC building with and without shear walls exposed to high temperatures developed due to fire. The results from this study indicate that the inclusion of shear walls at different locations in the building has a predominant effect on the stability of the RC building in the event of a fire.

Shear walls are known for their contribution in improving the lateral stiffness and thus controlling the story drift of the Reinforced Concrete (RC) buildings against earthquake loading. Although substantial research is available on shear wall-frame buildings, a detailed parametric study which can help the designers and field engineers to obtain an optimum arrangement of shear walls is missing in the literature. In the present study, a multi-story RC building, square in plan and assumed to be located in a seismically active city of the Kingdom of Saudi Arabia, was laterally stiffened with the shear walls of different thickness, height, configuration, and opening location. The building was then subjected to seismic forces, and the influence of shear walls in controlling the lateral response of the building was studied by varying the above parameters. The earthquake was considered from one direction only while studying the effect of the first two parameters (i.e., thickness and height) as the building and shear wall arrangements were symmetric along the two orthogonal directions. However, in case of third and fourth parameters (i.e., shear wall configuration and opening location), earthquake was considered from the two directions separately as the shear wall configuration and opening location were not symmetric in the two orthogonal directions. The results of the present study are very useful for obtaining the optimum amount and arrangement of shear walls in a given RC frame building against a specified seismic loading.

Reinforced Concrete (RC) frame buildings with shear wall are widely used in severe seismic zones. Shear walls are bearing system elements that provide the greatest resistance against hori-zontal force under the effect of the earthquake, limit displacements, and prevent torsions. A re-inforced concrete shear wall is one of the most critical structural members in buildings, in terms of carrying lateral loads. However, irregular layouts cause torsional irregularity in buildings. For this purpose, different shear wall frame reinforced concrete building models are designed. The model buildings have a regular formwork plan. The shear wall layout has different variations in each plan. These structure plans were mainly classified into two classes according to their tor-sional irregularities as structures with torsional irregularities and Structures with non-torsional ir-regularities. Artificial intelligence (AI) has revolutionized industries such as healthcare, agricul-ture, transportation, and education, as well as a variety of structural engineering problems. Arti-ficial intelligence is transforming decision-making easier and reshaping building design process-es to be smarter and automated. Artificial intelligence technology of learning from an existing knowledge base is used to automate various civil engineering applications such as compressive strength estimation of concrete, project pre-cost and duration, structural health monitoring, crack detection, and more. In this study, it is aimed to determine the structures with torsional irregulari-ty using artificial intelligence methods. Besides, the study is expected to introduce and demon-strate the capability of Artificial intelligence-based frameworks for future relevant studies within structural engineering applications and irregularities.

Experimental investigation of unbonded reinforced concrete PT shear wall under lateral loading: A state-of-the-art review

Comparative analyses of reinforced masonry and reinforced concrete shear walls with different end configurations: Seismic performance and economic assessment

Reinforced concrete (RC) coupled wall systems, compared with RC shear wall without opening, have more complex nonlinear behavior under the extreme earthquake loads due to the existence of coupling beams. The behavior characteristics induced by nonlinear shear deformation such as shear–flexure interaction, pinching effect, strength and stiffness deterioration are clearly observed in numerous cyclic tests of RC coupling beams and shear walls. To develop an analytical model capable of accurately and efficiently assessing the expected seismic performance of RC coupled wall systems, it is critical to define the appropriate key components models (i.e., nonlinear models of RC wall piers/shear walls and coupling beams). Classic fiber beam element based on the theory of Euler–Bernoulli beam is frequently adopted to simulate the nonlinear responses of slender RC wall piers and coupling beams in the literature because it is able to accurately model the response characters from interaction of axial–bending moment at the section level. However, classic fiber beam element cannot capture the nonlinear behaviors of non-slender structures mainly controlled by nonlinear shear deformation. To overcome this shortcoming, a modified force-based fiber element (MFBFE) including shear effect is introduced and used as the analysis element of non-slender RC coupling beams and shear walls. At the section level, a novel shear model for RC coupling beams and an existed shear model for RC shear walls are respectively added to this fiber element to simulate nonlinear responses of these two key components. The analytical model for RC coupled walls hence is formed through integrating the proposed models of these two key components. The validations with different experimental results of cyclic tests including key components and structural system reported in the literature using these proposed models are performed. Good agreements are achieved for all of these proposed models via comparisons between predicted results and experimental data.