Effect of foundation rocking on the seismic response of shear walls

2003 ◽  
Vol 30 (2) ◽  
pp. 360-365 ◽  
Author(s):  
Donald L Anderson
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Reduction Factor ◽  
Foundation Soil ◽  
Soil Response ◽  
Minimum Reinforcement ◽  
Seismic Shear ◽  
Fixed Base ◽  
R Value ◽  
Lift Off

Some designers have long known that elastically responding shear-wall or core-wall type high-rise structures will not overturn if the footing size is smaller than that required to resist the elastic forces. Most shear walls are designed and built with a yield hinge mechanism at the base using a relatively high value of the force reduction factor R, and the foundation should be stronger than the yield hinge strength if the wall is to perform as designed. Many walls, however, built with R = 2 are stronger than they need to be because of reasons such as architectural sizing and minimum reinforcement requirements. If for these cases the foundation is to be stronger than the wall, then it will in effect be designed for forces corresponding to an R value of <2. This study looks at the effect on the displacement of a shear-wall type structure if the footing is allowed to rock. The structure is kept elastic and the footing is sized to correspond to R values ranging from 1.0 to 3.5. The analysis uses gap elements to model the foundation soil response so that the footing can lift off the soil. Soil stiffness and strength are modelled for a rock and a firm clay site. The response of 7-, 15-, and 30-storey structures to 11 different acceleration records, modified to match a spectrum given in the 1995 National Building Code of Canada (NBCC) for Vancouver, is determined for the different footing dimensions. The results indicate that a footing sized for an R value of 2 does not result in a significant increase in displacement when compared with the fixed base elastic case. In the next version of the NBCC it is suggested that footings need not be designed for forces corresponding to R < 2.Key words: seismic shear walls, overturning, liftoff, rocking footings.

Stiffness and energy degradation of wood frame shear walls

1998 ◽  
Vol 25 (3) ◽  
pp. 412-423 ◽  
Author(s):  
Harry W Shenton III ◽  
David W Dinehart ◽  
Timothy E Elliott
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Oriented Strand Board ◽  
Test Procedure ◽  
Shear Walls ◽  
Shear Wall ◽  
Effective Stiffness ◽  
Seismic Shear ◽  
Wall Stiffness ◽  
Wood Frame

Tests have been conducted on wood frame shear walls to characterize the degradation of stiffness and energy dissipation that occurs under cyclic loading. A total of eight walls were tested, four sheathed in plywood and four sheathed in oriented-strand board. The tests were conducted in accordance with a draft test procedure recently proposed by the Structural Engineers Association of Southern California, which is based on a sequential phased displacement command input. The results indicate that effective stiffness decreases linearly with continued cycling at the same displacement and decreases with increasing amplitudes of displacement. Furthermore, the energy dissipation capacity of the wall decreases by 15-20% with the first cycle at a given amplitude, then decreases slightly with continued cycling at the same amplitude. The changes in effective stiffness and energy dissipation are generally independent of the type of sheathing for loads less than the wall ultimate, suggesting that the wall performance under cyclic loading is influenced more by the fastener and frame behavior. The results presented should be useful for design and for verifying hysteretic models of the shear wall behavior.Key words: cyclic, dynamic, energy dissipation, experimental, seismic, shear wall, stiffness, testing, timber, wood frame.

Seismic shear demand of ductile cantilever walls: a Canadian code perspective

1994 ◽  
Vol 21 (3) ◽  
pp. 363-376 ◽  
Author(s):  
André Filiatrault ◽  
Danilo D'Aronco ◽  
René Tinawi
Keyword(s):  
Time History ◽  
Shear Walls ◽  
Analytical Investigation ◽  
Reduction Factor ◽  
Seismic Shear ◽  
Force Reduction Factor ◽  
Force Reduction ◽  
Shear Failures ◽  
Nonlinear Time History ◽  
Shear Demand

During severe earthquakes, ductile flexural walls are expected to exhibit inelastic flexural behaviour while other brittle deformation mechanisms, such as shear, should remain elastic. The philosophy of the Canadian seismic provisions for flexural walls is based on the assumption that the force reduction factor is applicable to both flexure and shear. If the bending moments are limited because of the flexural strength of a wall, then the shear forces are considered to be limited by the same ratio. Recent case studies have not confirmed this philosophy. Brittle shear failures in walls are still possible even if their shear strengths are established by the Canadian standards. This paper presents an analytical investigation on the shear demand of ductile flexural walls designed for three different seismic zones in Canada. For each zone, an ensemble of code compatible historical earthquake ground motions is identified. The shear demand of each structure, under each earthquake record, is obtained by nonlinear time-history dynamic analyses. In 77% of the cases, the computed dynamic shear demand is higher than the current code shear strength. To address this issue, a force modification factor for shear, different from the one for flexure, is suggested for the Canadian code. Key words: earthquake, seismic response, shear walls.

scholarly journals Parametric Study of Buildings with and Without Shear Walls for Seismic Performance

2020 ◽  
Author(s):  
P.N. Pagare ◽  
P. R. Bhosale ◽  
A.P. Birar ◽  
V.D. Hayatnagarkar ◽  
D.C. Sawant
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Frame Structure ◽  
Dual Frame ◽  
Lateral Loads ◽  
Structural System ◽  
Soft Storey ◽  
High Rise ◽  
Seismic Shear ◽  
Earthquake Load

Shear walls are structural systems which provide stability to structures from lateral loads like wind, seismic loads. As shear wall resist major portions of lateral loads in the lowest portions of the buildings and the frame supports the lateral loads in the upper portions of the building which is suited for soft storey high rise building. The properties of these seismic shear walls dominate the response of the building and therefore, it is important to evaluate the seismic response of the walls appropriately. In this present study, main focus is to determine the solution for shear walls behavior in multi-storey building. Effectiveness of shear walls has been studied with the help of six different models. Model one is bare frame structural system, model two is dual frame structural system and model three is a complete shear wall structural system with internal walls in y-direction and model four is a similar model having internal shear walls in x-direction, model five is again a dual frame having columns at exterior and shear walls in interior placed in y-direction and model six is also an dual frame structure having columns at exterior and shear walls at interior placed in x-direction. An earthquake load is applied to a building of G+15 stories located in zone III, type of soil II and various other factors are considered. Parameters like displacement and storey drift are calculated in all the cases replacing column with shear walls and their locations.

Features of Elastic-plastic Deformation of Reinforced Concrete Shear-wall Structures under Earthquake Excitations

2020 ◽  
pp. 18-28
Author(s):  
Oleg Kabantsev ◽  
Karomatullo Umarov
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Nonlinear Dynamic Analysis ◽  
Shear Walls ◽  
Shear Wall ◽  
Reduction Factor ◽  
Reinforced Concrete Structures ◽  
Structural Elements ◽  
Plastic Deformations ◽  
Seismic Force

The article provides the results of studies the process of formation and development of plastic deformations in reinforced concrete structures with shear-wall under earthquake excitations. The studies are carried out by numerical methods using nonlinear dynamic analysis. The results of the research shown: that in the shear-wall elements of reinforced concrete structures the level of plastic deformations should be significantly reduced in relation to the normative level of plastics in other structural elements of the carrier system. The completed studies substantiated the introduction of differentiated values seismic-force-reduction factor for different types of structural elements on shear-walls reinforced concrete structures of earthquake-resistant buildings.

Seismic shear demand on wall segments of ductile coupled shear walls

2000 ◽  
Vol 27 (3) ◽  
pp. 506-522 ◽  
Author(s):  
O Chaallal ◽  
D Gauthier
Keyword(s):  
Amplification Factor ◽  
Shear Walls ◽  
Reduction Factor ◽  
Dynamic Amplification Factor ◽  
Overstrength Factor ◽  
Seismic Shear ◽  
Force Reduction Factor ◽  
Force Reduction ◽  
Dynamic Amplification ◽  
Shear Demand

This paper presents the results of nonlinear dynamic analyses carried out on ductile coupled shear walls (CSWs) to investigate the seismic shear demand on wall segments. The objectives of the present study were to evaluate the dynamic amplification and establish a code-format force reduction factor for shear, applicable in Canada. The study considered three Canadian seismic zones (4, 5, and 6), five numbers of storeys (6, 10, 15, 20, and 30), three degrees of coupling (low, medium, and high), and 10 historical earthquake records encompassing a broad range of frequency contents. Overall, 450 analyses were performed. Results indicate that the New Zealand amplification factor βv presently used in Canada overestimates the dynamic amplification. Additionally, the use of the overstrength factor for shear γp for tension walls may underestimate their shear resistance and result in a shear failure. Conversely, the use of γp for compression walls provided a reasonable factor of safety. Finally, for the shear design of CSWs, two alternative approaches are suggested. The first involves the use of a force reduction factor for shear, Rv, including the dynamic amplification factor γd and the overstrength factor γp as follows: Rv = 2.0 for Za > Zv, Rv = 1.0 for Za < Zv, and Rv = 1.3 for Za = Zv, where Za and Zv are acceleration- and velocity-related zonal identifiers. The second approach implies the use of the overstrength factor γp of the compression wall for both walls of CSWs and βv = 1.0.Key words: coupled shear walls, reinforced concrete, degree of coupling, seismic, frequency content, shear demand, dynamic amplification factor, force reduction factor for shear.

scholarly journals Numerical study on the seismic performance of hybrid steel moment frames with CLT balloon shear walls

2020 ◽  
Author(s):  
◽  
Mehdi Khajehpour
Keyword(s):  
Numerical Study ◽  
Time History ◽  
Shear Walls ◽  
Shear Wall ◽  
Hybrid Structure ◽  
Reduction Factor ◽  
Base Shear ◽  
Moment Frames ◽  
Response Modification Factor ◽  
Capacity Curves

A proposed hybrid lateral load resisting system combining a moderately ductile steel moment resisting frame (SMRF) with Cross-laminated Timber (CLT) balloon-framed shear walls is investigated on 8, 12 and 16-storey case-study buildings using equivalent static, linear dynamic (modal), nonlinear static (push-over) and nonlinear dynamic (time history) analyses. First, a SMRF is designed using ETABS, then the hybrid structures are analysed in OpenSees. By adding the CLT shear wall to steel moment frame, the period of structure decreased and its stiffness increased. The time history analyses result revealed that by adding the CLT shear wall the maximum drift decreased, while the maximum base shear in hybrid structure slightly increased. The hold down uplift forces under earthquake records are reported and compared to each other. Using push-over capacity-curves, a ductility reduction factor of 3.6, an over strength factor of 1.57 and a seismic response modification factor of 5.67 are derived.

Effects of openings on the seismic behavior and performance level of concrete shear walls

2019 ◽  
Author(s):  
Hossein Alimohammadi ◽  
Mostafa Dalvi Esfahani ◽  
Mohammadali Lotfollahi Yaghin
Keyword(s):  
Static Analysis ◽  
Cross Section ◽  
Seismic Behavior ◽  
Shear Walls ◽  
Shear Wall ◽  
Constant Cross Section ◽  
Added Resistance ◽  
Different Shapes ◽  
And Performance ◽  
Abaqus Software

In this study, the seismic behavior of the concrete shear wall considering the opening with different shapes and constant cross-section has been studied, and for this purpose, several shear walls are placed under the increasingly non-linear static analysis (Pushover). These case studies modeled in 3D Abaqus Software, and the results of the ductility coefficient, hardness, energy absorption, added resistance, the final shape, and the final resistance are compared to shear walls without opening.

scholarly journals Lateral resistance of mass timber shear wall connected by withdrawal-type connectors

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Sung-Jun Pang ◽  
Kyung-Sun Ahn ◽  
Seog Goo Kang ◽  
Jung-Kwon Oh
Keyword(s):  
Experimental Data ◽  
Seismic Design ◽  
Shear Walls ◽  
Shear Wall ◽  
Vertical Load ◽  
Lateral Resistance ◽  
Kinematic Models ◽  
Mass Timber ◽  
Timber Shear Walls ◽  
Timber Shear Wall

AbstractIn this study, the lateral resistances of mass timber shear walls were investigated for seismic design. The lateral resistances were predicted by kinematic models with mechanical properties of connectors, and compared with experimental data. Four out of 7 shear wall specimens consisted of a single Ply-lam panel and withdrawal-type connectors. Three out of 7 shear wall specimens consisted of two panels made by dividing a single panel in half. The divided panels were connected by 2 or 4 connectors like a single panel before being divided. The applied vertical load was 0, 24, or 120 kN, and the number of connectors for connecting the Ply-lam wall-to-floor was 2 or 4. As a result, the tested data were 6.3 to 52.7% higher than the predicted value by kinematic models, and it means that the lateral resistance can be designed by the behavior of the connector, and the prediction will be safe. The effects of wall-to-wall connectors, wall-to-floor connectors and vertical loads on the shear wall were analyzed with the experimental data.

Study on Seismic Behavior of the L-Shape Steel Reinforced Concrete Short-Pier Shear Wall with Different Concrete Strength

2013 ◽  
Vol 353-356 ◽  
pp. 1990-1999
Author(s):  
Yi Sheng Su ◽  
Er Cong Meng ◽  
Zu Lin Xiao ◽  
Yun Dong Pi ◽  
Yi Bin Yang
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Behavior ◽  
Concrete Strength ◽  
Shear Walls ◽  
Shear Wall ◽  
Simulation Software ◽  
Steel Reinforced Concrete ◽  
Shrinkage Effect

In order to discuss the effect of different concrete strength on the seismic behavior of the L-shape steel reinforced concrete (SRC) short-pier shear wall , this article analyze three L-shape steel reinforced concrete short-pier shear walls of different concrete strength with the numerical simulation software ABAQUS, revealing the effects of concrete strength on the walls seismic behavior. The results of the study show that the concrete strength obviously influence the seismic performance. With the concrete strength grade rise, the bearing capacity of the shear wall becomes large, the ductility becomes low, the pinch shrinkage effect of the hysteresis loop becomes more obvious.

Study on the shear wall structure with combined form of replaceable devices

2017 ◽  
Vol 21 (9) ◽  
pp. 1327-1348
Author(s):  
Cong Chen ◽  
Renjie Xiao ◽  
Xilin Lu ◽  
Yun Chen
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Performance Comparison ◽  
Wall Structure ◽  
Structural Part ◽  
Coupled Shear Wall ◽  
Wall Structures ◽  
Strength And Stiffness ◽  
Energy Dissipated ◽  
Resilient Structure

Structure with replaceable devices is a type of earthquake resilient structure developed to restore the structure immediately after strong earthquakes. Current researches focus on one type of the replaceable device located in the structural part that is most likely to be damaged; however, plastic deformation would not be limited in a specific part but expand to other parts. To concentrate possible damage in shear wall structures, combined form of replaceable devices was introduced in this article. Based on previous studies, combined form of replaceable coupling beam and replaceable wall foot was used in a coupled shear wall. Influences of the dimension and location of the replaceable devices to the strength and stiffness of the shear wall were investigated through numerical modeling, which was verified by experimental data. Performance comparison between the shear walls with one type and combined form of replaceable devices and the conventional coupled shear wall was performed. In general, the shear wall with combined form of replaceable devices is shown to be better energy dissipated, and proper dimensions and locations of the replaceable devices should be determined.

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