Chai, et. al (2005)

Minimum thickness for ductile RC structural walls

Reinforced concrete structural walls are generally recognized as efficient lateral force resisting systems for multi-storey buildings, due to their ability to control drift demand under service load conditions as well as their inherent ductility capacity under ultimate seismic conditions. Large tensile strains are a cause for concern since the stability of the wall depends on the magnitude of the tensile strain imposed on the wall. The minimum wall thickness is outlined in this paper and results are presented for a number of parameters including the ground motion intensity, longitudinal reinforcement ratio, floor weight, wall-to-floor area ratio and number of

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stories. The minimum wall thickness is compared with recommendations in current building codes. Study in this paper also indicated that the minimum wall thickness is not sensitive to the tributary floor weight. The minimum wall thickness is rather sensitive to the wall height, or equivalently, the number of stories. The increase in wall thickness is due to the changing shape of the elastic response acceleration spectrum, which generally indicates a softening of the site for decreasing a/v ratio

Rana, et. al (2004)

Pushover analysis of a 19 story concrete shear wall building

Pushover analysis is a useful tool of Performance Based Seismic Engineering to study post-yield behaviour of a structure. It is more complex than traditional linear analysis, but it requires less effort and deals with much less amount of data than a nonlinear response history analysis. Pushover analysis was performed on a nineteen story concrete building with shear wall lateral system and certain unique design features. Normally, loads on these structures are low and result in elastic structural behaviour. However, under a strong seismic event, a structure may actually be subjected to forces beyond its elastic limit. The plastic rotations of the hinges developed, as calculated by SAP2000, were checked and found to be within the limits suggested by FEMA and ATC guidelines for the intended design objective of life safety.

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Sud, et.al (2014) Effect of different shear wall configurations on seismic response of a moment-resisting frame

Use of shear walls in RC buildings is one of the most commonly used strategies for earthquake mitigation. a five-storey RC building located in seismic zone-V is considered with four shear walls. These frames are analysed for seismic forces to assess performance in terms of base shear, storey drift, member forces and joint displacements. The frame with shear walls at core and centrally placed at exterior bays showed significant reduction of order 29% to 83% in lateral displacement. The reduction in bending moments is approximately 70% to 85% for interior and perimeter columns respectively. Shear and axial forces in columns have reduced by 86% and 45% respectively.

Henry, et.al (2013)

Assessment of the minimum vertical reinforcement limits for RC walls

The crack width that is required to accommodate the inelastic displacement of the building resulted in fracture of the vertical reinforcing steel. This type of failure is characteristic of RC members with low reinforcement contents, where the area of reinforcing steel is insufficient to develop the tension force required to form secondary cracks in the surrounding concrete. A series of moment-curvature analyses were conducted for an example RC wall based on the Gallery Apartments building in Christchurch. The analysis results indicated that even when the NZS 3101:2006 minimum vertical reinforcement limit was satisfied for a known concrete strength, the

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wall is still susceptible to sudden failure unless a significant axial load was applied.

Yuen, et. al (2014)

Axial compression effect on ductility design of RC structural wall

Reinforced concrete walls can render medium- to high-rise buildings excellent lateral stability and ductility, modern building design often lead to the vertical structural members subjected to very high axial compression ratio (ACR), which can deprive the inherent ductility. a comprehensive statistical analysis with 474 sets of experimental data has been conducted. Stipulated limits on ACR and their evaluation methods in various design codes are then compared. the ductility of the walls is generally diminishing with increasing of ACR and this trend is particularly noticeable for slender walls with aspect ratio greater 1.5. Provisions on the limits of ACR stipulated in various codes are then compared and the expected attainable ductility of RC walls designed to different codes are evaluated against the statistical analysis results. The ACR limits for slender walls may be relaxed, whereas the ACR limits for squat walls are seemingly needed to be tightened up.

Choudhary (2014)

Pushover analysis of RC frame building with shear wall

The present study pushover analysis has been done on two multi-storeyed R.C. frame building. The paper highlight the effect of shear wall on R.C frame building when shear wall providing along the longer and shorter side

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of the building. The base shear and displacement will decreases of building. The comparative study has been done for base shear, story drift, spectral acceleration, spectral displacement, story displacement. Provision of shear wall results in a huge decrease in base shear and roof displacement both symmetrical building and un-symmetrical building. The performance based seismic design obtained satisfies the acceptance criteria for immediate occupancy and life safety limit states for various intensities of earthquakes Dai, et. al (2014)

Ductile design of slender reinforced concrete structural walls

Slender reinforced concrete structural walls are commonly used in mid- to high-rise buildings as a main lateral load resisting element in earthquake regions. The damage sustained by concrete walls in recent earthquakes has demonstrated that current design requirements of these walls may need modifications. A simplified computational method to estimate force-displacement response of a structural wall, utilizing the moment-curvature relationship, was developed and validated using experimental data. The influence of the following six design parameters on the structural behaviour of slender rectangular walls was investigated: aspect ratio; longitudinal reinforcement ratio; volume ratio of spiral reinforcement in wall boundary elements; length of confined wall boundary elements; axial loading ratio; and distribution of longitudinal reinforcement. The results of the analytical study found that the current code requirements for boundary element length and amount of the transverse reinforcement are not sufficient and need to be increased for improved performance.

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Shayanfar, et.al (2011)

Numerical investigation failure mechanism of slender structural walls

The overall behaviour of the slender structural wall is determined by the behaviour of the plastic hinge region at the wall base. A slender structural wall subject to a lateral load is damaged at the wall base. The failure of a slender structural wall with confined end-zones is caused by the crushing of the confined concrete, crushing of the unconfined concrete, fracture and buckling of the flexural re-bars, and fracture of the lateral re-bars. The slender structural walls have flexural behaviour and the behaviour of bending members can be explained by moment–curvature relation. The moment-curvature relation for a section is determined using an analysis procedure that satisfies the requirements of strain compatibility, equilibrium of forces, and the stress-strain relations. The occurrence of each failure modes depends on the quantity of confinement reinforcement, the depth of compressive zone, the depth of confined zone and properties of concrete and steel.

Islam, et.al (2015)

Displacement based evaluation for confinement requirement of boundary elements of shear wall and retrofit design using carbon fiber sheet(CFS)

An analytical procedure to determine the need for concrete confinement at the boundaries of the RC structural walls subjected to earthquake load is presented by relating the displacement demand of the building system to the local deformation in the wall cross section. The primary variables used to determine the need for confinement are the ratio of wall cross sectional

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area, the wall axial load and the wall reinforcement ratio. The evaluation of need for confinement at the boundaries of the shear wall, evaluate the effectiveness of using externally bonded carbon fiber sheet (CFS) to increase the confinement of boundary elements of the shear wall. With the confinement of CFS, a desirable ductile flexural failure mode rather than a brittle shear failure mode can be achieved. The ultimate deformation capacity of the fully wrapped wall and wall retrofitted in the boundary region only with anchoring was increased by 22% and 70% respectively than the baseline specimen.

Beyer (2011)

Shear deformations of slender reinforced concrete walls under seismic loading

Slender reinforced concrete (RC) walls, which are designed to have a larger shear resistance than flexural resistance, and whose behaviour is therefore controlled by flexure rather than shear, behave in a ductile flexural mode when loaded beyond the elastic limit. The inelastic seismic behaviour of such walls can be analysed using advanced models that account for the biaxial in-plane stress state in the RC elements. The distribution of shear strains within the walls and the variation of shear deformations with top displacements is discussed. It is shown that for shear walls whose shear-transfer mechanism is not significantly deteriorating, the ratio of shear-to flexural deformations remains approximately constant over the entire range of imposed displacement ductilities, whereas for walls whose shear-transfer mechanism is significantly degrading, the ratio of shear-to-flexural

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deformations increases. For RC walls forming a flexural hinge and a stable shear-transfer mechanism, the ratio of shear-to-flexural displacement remains approximately constant over the entire ductility range once the walls have reached their nominal strength.

Carrillo (2014)

Displacement ductility for seismic design of RC walls for low rise housing

The paper compares and discusses displacement ductility ratios of reinforced concrete walls typically used in one and two story houses. Ductility is investigated by assessing response measured on 39 walls tested under shaking table excitations and quasi-static lateral loads. Variable studied were the height-to-length ratio and walls with openings, type of concrete and steel ratio and type of web reinforcement. An equation to estimate the available ductility of a wall is proposed. The available ductility of structural elements an system controlled by shear deformations should be assessed using realistic experimental techniques. The maximum drift ratio for evaluating ductility capacity is associated with one of the two following scenarios, when a 20% drop in peak strength is observed or when web shear reinforcement is fractured. Measured data revealed that displacement ductility ratios varying between 1.63 and 2.92 may be achieved for walls with web shear reinforcement made of deformed bars, and between 1.39 and 2.71 for walls with welded-wire mesh.

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Hagen (2012)

Performance based analysis of a reinforced concrete shear wall building

According to the new fib Model Code 2010 the design shear resistance of a reinforced concrete (RC) structure can be evaluated through analytical and numerical calculation methods that fall into four different levels of approximations; the complexity and the accuracy of the calculated shear resistance increases with increasing the level of approximation. Nonlinear finite element (NLFE) analyses belong to the highest level of approximation (Level IV) thanks to their advantage to take into account real material properties and “hidden” capacities of the structure. The analytical and numerical results obtained have been compared with experimental results. Parametric studies have also been carried out on the slabs in order to focus on the main sensitive parameters that influence the results obtained from numerical simulations and in order to obtain reliable and, at the same time, safe results.

Nakashi, et al (1992)

Experimental study on deformation capacity of reinforced concrete shear walls after flexural yielding

Multi story shear walls installed in high rise reinforced concrete buildings effectively reduce seismic vibration. In order to improve the seismic performance of such shear walls, it is best that the failure modes of the shear walls are flexural as a flexural mode is the most ductile kind of failure mode. Lateral loading tests on five shear walls were conducted. The

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relationship between the compressive ductility of the boundary columns and panels and the deformation capacity of shear walls was the analysed. The concrete confinement of the boundary columns were observed to illustrate by the compressive crumbling of the boundary columns or panels. The deformation capacity of the shear wall increased as the ratio of the horizontal reinforcing in the panels increased. The confinement of the concrete using the confining reinforcing in the panels had a significant effect on the deformation capacity.

Taylor, et.al (1996)

Experimental verification of displacement based design procedures for slender RC structural walls

The paper presents the results of experimental studies of large scale wall specimens with rectangular, tee shaped and barbell shaped cross sections to verify displacement based design procedure. The procedure evaluates the need for special transverse reinforcement at the wall boundaries to provide concrete confinement and suppress buckling of the longitudinal reinforcement. Six wall specimens were tested under reverse cyclic loading and a constant axial load of approximately .10Agfc’. It was found that the displacement based design is a flexible design tool, special attention is to be required for the design of walls with tee-shaped cross sections. In areas of high seismic risk, structural walls were not designed to remain elastic during a severe earthquake, therefore in elastic deformations were expected, usally at the base of the wall. In order to exhibit stable, inelastic behavior, the wall must be specially detailed, that is transverse reinforcement must be

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provided in regions of high strain. The study shows that the displacement based design methodologies are an effective tool for evaluating structural wall behavior.

Wallace (2012)

Performance of structural walls in recent earthquake and test and implications for US building codes

Design and construction practice for structural walls has evolved significantly over the last 20 years and engineers have pushed design limits in recent years, optimizing economy and design. In earthquakes, structural wall damage included boundary crushing, reinforcement fracture, and global wall buckling. Recent laboratory tests also have demonstrated inadequate performance, indicating a need to review code provisions, identify shortcomings and make necessary revisions. Wall performance in recent earthquakes and laboratory tests is reviewed and American Concrete Institute 318 provisions are reassessed to identify possible shortcomings. The findings suggest a number of issues that require more in-depth study, particularly for thin walls, as well as approaches that could be implemented to address these issues. A limit on slenderness, e.g., tw ≥ hs/16 is recommended, along with commentary to note that a lower ratio many be needed to avoid lateral instability at the web boundaries of flange walls.

Shokrzadeh, et. al (2012)

Study on Nonlinear static analysis of RC frames retrofitted with steel plate shear wall

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This paper concentrates on analytical studies of steel plate shear walls (SPSWs) added to concrete frames. Several tested concrete frames are considered. The practical application of nonlinear Seismostruct material models in the analysis of RC structures is considered. A series of analysis for a frame with different material models is performed. The results are compared and suitable material types are chosen. In addition, the ability of the two finite element programs (Seismostruct, SAP2000) to perform nonlinear static analysis is compared. It can be concluded that the proposed FE modelling can accurately represent many of the main features of the behaviour of concrete frames retrofitted by SPSWs. The pushover curves were shown to be equally well predicted by a monotonic pushover analysis using a FE model, when comparing to the experimental results.

Mathews, et. al (2013)

Structural behavior of shear wall based on nonlinear analysis

The objective of the paper is to study the nonlinear behavior of a reinforced concrete shear wall under lateral earthquake load. For this a model of six storied RC structure is considered. The nonlinear behavior of the reinforced shear walls is then studied by static pushover analysis using the general purpose FE-program ANSYS. In the pushover analysis lateral load is stepwise increased from zero to twice the design earthquake load. From the static pushover analysis it is possible to get information about crack pattern, initial cracks, tensile cracks and crushing. The crack widths calculated showed a gradual increase based on an increase in steel stress. The crack

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widths calculated by using the information from static pushover analysis seem to be promising and useful while designing and analyzing structures in seismic zones.

Irappa Kam,et. al (2015)

Nonlinear static analysis of asymmetric building with and without shear wall

The main objective of the paper is to study the performance level and behaviour of structure in presence of shear wall for plan irregular building with re-entrant corners. The parameters considered in this paper are Base shear, Displacement and performance levels of the structure. The seismic codes for irregularities are as per the clauses defined in IS-1893:2002 and pushover analysis procedure is followed as per the prescriptions in ATC-40. The model is analysed using SAP2000 software. The base shear of the building increase with the addition of the shear wall as the load resisting capacity increases. The addition of shear wall significantly reduces the displacement in the structures when compared with the structures without shear wall.

1.2 Critique

From above literature review we have seen that so many works has been done on shear wall for non-linear analysis and the behavior it performs under seismic response in RC structural walls.

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But the work has not been done on percentage reinforcement on boundary element and the thickness of boundary element for a particular height of the building.

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