Modified response spectrum analysis to compute shear force in tall RC shear wall buildings

Khy, Kimleng; Chintanapakdee, Chatpan; Warnitchai, Pennung; Wijeyewickrema, Anil

doi:10.1016/j.engstruct.2018.11.022

Cited by 14 publications

(13 citation statements)

References 25 publications

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“…The authors indicated that shear forces obtained from MRSA matched with the corresponding demands from nonlinear response history analyses (NLRHA) with a reasonable degree of accuracy while shear forces obtained from RSA procedure were significantly lower than those from NLRHA for 20‐, 33‐ and 44‐story buildings. Khy et al [ 26 ] evaluated the accuracy of the RSA procedure in tall RC buildings designed according to ACI 318M‐14 [ 27 ] and ASCE 7‐10. [ 28 ] The authors emphasized that the shear values obtained from the RSA procedure should not be used in the design, as they are too small compared with the demand values obtained from nonlinear response history analysis (NLRHA).…”

Section: Introductionmentioning

confidence: 99%

A new approach for the computation of design shear force in reinforced concrete walls subjected to seismic loads

Seçkin

Doran

2022

Structural Design Tall Build

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Summary This paper investigates the dynamic shear amplification in reinforced concrete shear walls designed according to the seismic provisions of the current Turkish Building Earthquake Code (TBEC‐2018). Shear walls with a high ductility level and different aspect ratios are examined to evaluate the design shear force calculated by using the dynamic amplification factor (βv) and overstrength factor (D) defined in TBEC‐2018. For this purpose, response spectrum analyses (RSAs) are first carried out on two‐dimensional cantilever shear walls with heights of 30, 45, and 60 m and with lengths of 1.5, 3, and 4.5 m in the plan. Then, a total of 198 nonlinear time history analyses (NLTHAs) are performed with real and simulated ground motions matched to the elastic design spectrum defined in TBEC‐2018. The comparison of the design shear forces obtained from RSA and the shear demands obtained from NLTHA along the heights of the walls reveals that the design shear forces calculated according to TBEC‐2018 may underestimate the actual shear demands from studied ground motions. Moreover, the applicability of the updates proposed to TBEC‐2018 for the design shear force and shear force diagram along the wall height in reinforced concrete shear wall‐frame systems to cantilever shear walls is also examined.

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Section: Introductionmentioning

confidence: 99%

A new approach for the computation of design shear force in reinforced concrete walls subjected to seismic loads

Seçkin

Doran

2022

Structural Design Tall Build

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“…Several studies have shown the inappropriateness of this analysis in true estimation of the story shears and moments of tall buildings with RC wall core. [17][18][19] Some reasons have been reported for this incorrectness. Khy et al [19] believed that use of a single response modification factor (R) to reduce elastic forces contributed from all modes in the RSA procedure is the primary cause.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] Some reasons have been reported for this incorrectness. Khy et al [19] believed that use of a single response modification factor (R) to reduce elastic forces contributed from all modes in the RSA procedure is the primary cause. In addition to this reason, Munir and Warnitchai [17] described that the flexural yielding in the plastic hinge at the wall base can effectively suppress the seismic demands of the first mode.…”

Section: Introductionmentioning

confidence: 99%

Comparative study on the effect of outrigger on seismic response of tall buildings with braced and RC wall core. I: Optimum level and examining modal response spectrum analysis reliability

Samadi

Jahan

2021

Structural Design Tall Build

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Summary Designers usually use modal response spectrum analysis (MRSA) in design of tall buildings. This paper studies the reliability of this technique in predicting real seismic behavior of tall buildings with outrigger and belt truss. Four tall buildings utilizing either braced or reinforced concrete shear wall core with 28 and 56 stories were designed as the base models according to current design codes. Outrigger and belt truss were added at quarters of the structure height generating 44 structural models. Results obtained from MRSA of these models are discussed and compared to those obtained from nonlinear time history analysis (NLTHA). It was observed that MRSA unrealistically overestimates beneficial effects of outrigger on drift reduction of tall buildings with braced core. NLTHA showed that the maximum lateral displacements of the structures with braced core are less than those of buildings with RC shear wall, but they experience more residual displacements. Adding outrigger could reduce maximum lateral displacement of buildings with RC shear wall core (in excess of 30%) but had minor effect on this index in structures with braced core (less than 10%). Outrigger did not consistently reduce maximum drift under all records, except for the story where it is located. Although outrigger could not reliably decrease residual drift of structures with braced core, it significantly decreased this index when applied at any level of buildings with RC shear wall core, under all studied records. Applying outrigger increased story shears and NLTHA showed that it creates a sudden jump in shear at its placement story.

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“…The over-strength factor resulted from a flexural strength design of beams and columns is also used to determine shear forces for use in design of beams and columns in the moment resisting frame [5][6][7][8]. The over-strength factor is also related to shear-amplification problem in shear walls as it can increase shear forces of RC shear walls [9][10][11]. Therefore, accurate estimation of the over-strength factor is important to compute the design forces of those structural elements.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Different Sources of Over-Strength in Seismic Design of a Reinforced Concrete Tall Building

Khy¹,

Chintanapakdee²

2019

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An over-strength factor in seismic design plays an important role in computing actual forces in a structural member designed to remain elastic. However, sources contributing to this over-strength have not yet been systematically quantified for tall buildings. This paper aims to investigate the contribution from different sources of the over-strength factor in a reinforced concrete (RC) tall building. The effect of how floor slabs are modeled in nonlinear structural models to compute lateral load capacity of the building is also investigated. 39-story RC building subjected to earthquake ground motions in Bangkok was first designed according to the current building codes. Then, pushover analysis was conducted to compute lateral load capacity of the building with three different specified strengths: design strength (with  factor), nominal strength (without  factor), and actual strength (with material over-strength). It was found that modeling floor slabs by elastic shell elements in nonlinear structural model should not be used in computing the ultimate lateral load capacity of the building because the contribution from slab-column framing action is unrealistically large at large roof displacement. When floor slabs are modelled by inelastic effective beam width approach, slab-column framing action contributes about 60% of the ultimate lateral load capacity of the building. The building has an overall lateral over-strength factor of 3.36 to 3.71. The over-strength factor arising from design process is 2.12 to 2.42 in which the contributions from strength reduction factor, material over-strength, and other sources involving the design requirements are about 1.10, 1.17, and 1.77, respectively. The over-strength factor arising from redundancy due to the redistribution of internal forces is about 1.55 and the contribution from steel strain hardening to the over-strength factor is relatively small.

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Modified response spectrum analysis to compute shear force in tall RC shear wall buildings

Cited by 14 publications

References 25 publications

A new approach for the computation of design shear force in reinforced concrete walls subjected to seismic loads

A new approach for the computation of design shear force in reinforced concrete walls subjected to seismic loads

Comparative study on the effect of outrigger on seismic response of tall buildings with braced and RC wall core. I: Optimum level and examining modal response spectrum analysis reliability

Quantification of Different Sources of Over-Strength in Seismic Design of a Reinforced Concrete Tall Building

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