The cause of unproportionately large higher mode contributions in the inelastic seismic responses of high‐rise core‐wall buildings

Munir, Anum; Warnitchai, Pennung

doi:10.1002/eqe.2182

Cited by 39 publications

(44 citation statements)

References 13 publications

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“…21 that the seismic shear demands of W2 from NLRHA procedure are about 2 times as high as the corresponding shear demands from RSA procedure and that their distribution patterns throughout entire height are almost the same. These results agree quite well with the results of Klemencic et al [7], and Munir and Warnitchai [9]. Similarly, the bending moment from NLRHA is also about 2 times the corresponding demands from RSA procedure throughout the entire height of the building as depicted in Fig.…”

Section: Verification Of Rsa Proceduressupporting

confidence: 90%

“…In MMS method, the elastic seismic shear demand is reduced by a seismic modification factor only in the first vibration mode and then combined with the elastic shear demand of other higher modes into total response. Munir and Warnitchai [9] used a method called uncoupled modal response history analysis (UMRHA) adapted from Chopra and Goel [23] to decompose the inelastic seismic responses into the contribution of each vibration modes. The results are compared with the demands from RSA procedure (with R=1 and R=5.5) and they found that the demands from UMRHA matched RSA (R=5.5) only in the first mode and reasonably close to RSA (R=1) in other higher modes.…”

Section: 3mentioning

confidence: 99%

“…Other similar findings done by Klemencic et al [7] and Sangarayakul and Warnitchai [8] have also confirmed the insufficiency of RSA procedure on tall buildings. More recently, Munir and Warnitchai [9] studied and explained the causes of unsafe design by RSA procedure based on a 40-story case study building, three main differences in both analyses (RSA and NLRHA) such as: damping ratio, level of ground motion (DBE and MCE), and material over-strength used only in NLRHA were considered. And despite these differences were adjusted and made the same, the seismic shear demand from NLRHA is still about 1.5 times the corresponding demand from RSA procedure.…”

Section: Introductionmentioning

confidence: 99%

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Seismic Shear Forces in Shear Walls of a Medium-Rise Building Designed by Response Spectrum Analysis

Leng¹,

Chintanapakdee²,

Hayashikawa³

2014

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Abstract. According to ASCE7-05, response spectrum analysis (RSA) procedure can be used to determine the seismic demands of the structures for the seismic design of any type of structures. However, this design procedure has been found to be inappropriate for medium-rise and high-rise buildings. This paper is aimed at verifying the RSA procedure prescribed in the current Thai seismic design code which is based on ASCE7-05 and proposing appropriate modification to the design shear force from RSA procedure. A 16-story medium-rise reinforced-concrete core-wall case-study building was first designed based on RSA procedure and then the non-linear response history analysis (NLRHA) was performed to determine the more accurate seismic demands of the structure. The results show that seismic shear demand of the shear wall from non-linear analysis is about 2 times the shear capacity of the wall designed by RSA procedure. This could lead to shear failure in the shear walls designed by RSA procedure. To avoid shear failure in the shear wall elements, the shear demands in the wall elements designed by RSA procedure needs to be amplified by a factor of 2, which is equivalent to reducing the response modification factor R = 5.5 in ASCE7-05 to R = 2.75 (for shear force in the shear wall only).

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Section: Verification Of Rsa Proceduressupporting

confidence: 90%

Section: 3mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismic Shear Forces in Shear Walls of a Medium-Rise Building Designed by Response Spectrum Analysis

Leng¹,

Chintanapakdee²,

Hayashikawa³

2014

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“…However, this procedure requires to perform the multimode pushover analysis of an inelastic structural model and, therefore, can also be viewed as a simplification of the modal pushover analysis (MPA) proposed by Chopra and Goel. [13] More recently, Ahmed and Warnitchai [14] and Mehmood et al [15,16] applied the uncoupled modal response history analysis (UMRHA)…”

Section: Background and Motivationmentioning

confidence: 99%

A modified response spectrum analysis procedure to determine nonlinear seismic demands of high‐rise buildings with shear walls

Najam

Warnitchai

2017

Structural Design Tall Build

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SummaryThe standard response spectrum analysis (RSA) procedure prescribed in various design codes is commonly used by practicing engineers to determine the seismic demands for structural design purpose. In this procedure, the elastic force demands of all significant vibration modes are first combined and then reduced by a response modification factor (R) to get the inelastic design demands. Recent studies, however, have shown that the response of higher vibration modes may experience much lower level of nonlinearity, and therefore, it may not be appropriate to Over last few decades, the structural design against earthquakes has passed through a continuous process of evolution. The story that started from a simple mass-proportional lateral load resisted by elastic action has now evolved into an explicit consideration of design earthquakes applied to the detailed nonlinear finite-element models. The exponential growth in computational power in recent years is continuously narrowing the industryacademia gap by providing the cutting-edge research and technology to practicing engineers at their doorstep. As a result, the structural designers nowadays are equipped with far more aids and tools compared to a couple of decades ago. Moreover, recent advancements in nonlinear modeling techniques have also opened a whole new research area dealing with constructing computer models with close-to-real behaviors. With such a range of options available, the choice of modeling scheme and the analysis procedure for design decision making often becomes a matter of "the more the sweat; the more the reward" for designer. However, this is not a complete depiction of this story. If on one side, these advancements are bringing more sophistication to design process (in terms of better structural idealization and faster numerical solvers), they are also making the process complex, extra skill-demanding, and sometimes unnecessarily intricate. From design point-of-view, the real purpose of structural analysis is not merely to simulate the detailed 3D models and compute design demands, but also to understand the complex structural behavior. This understanding may not always guaranteed by complicated modeling techniques or analysis procedures and faster numerical solvers. In fact, it can be more effectively developed using convenient methods capable of simplifying and clearly explaining the complex response in terms of its components. This insight should then help in devising the most efficient design scheme in terms of reduction in cost, time, effort, and other

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“…The design forces in this method are obtained by using a single response modification factor (R) for all modes of response to reduce the elastic forces computed by RSA procedure. However, previous researchers have found that flexural yielding at the base region of the wall reduced mainly the first-mode shear but higher-mode shears were not significantly affected by inelastic action [2][3][4][5]. Most studies were based on comparing results from RSA procedure to the 'referenced' results from nonlinear response history analysis (NLRHA), which is considered as the most accurate method available to compute design forces of a structural system subjected to earthquake loading.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Seismic Shear Demands of RC Core Walls in Thailand Determined by RSA Procedure

Khy¹,

Chintanapakdee²

2017

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Abstract. ASCE 7 allows structural engineers to use Response Spectrum Analysis (RSA) procedure to compute the seismic design forces of the structures. However, seismic shear demands of reinforced concrete (RC) walls determined by RSA have been found to be inadequate by many researchers. This paper aims to investigate the seismic shear demands of RC core walls from low-rise to high-rise buildings. RC split core walls in five buildings varying from 5 to 25 stories subjected to earthquake ground motions in Bangkok and Chiang Mai of Thailand were first designed by RSA procedure in ASCE 7-10. Then nonlinear response history analysis (NLRHA) was conducted to compute more accurate seismic demands of the structures. The results demonstrated that shear demands of core walls from NLRHA were significantly larger than those from RSA procedure. The shear amplifications of core walls in cantilever-wall direction were larger than those in coupledwall direction. The two building locations having different spectrum shapes led to different shear amplifications. Hence, an empirical formula cannot be applied to every location. In Bangkok, it is found that Rejec et al. (2012)'s equation could well estimate shear forces in cantilever direction of core walls but it significantly overestimated shear forces in coupled direction of core walls. In Chiang Mai, Luu et al. (2014)'s equation provided good estimation of shear forces in both directions of core walls. Beside these two equations, the shear magnification factor equation in EC8 is found acceptable to be adopted to multiply with shear force from RSA procedure before using it as design shear force of RC core wall in both Bangkok and Chiang Mai.

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The cause of unproportionately large higher mode contributions in the inelastic seismic responses of high‐rise core‐wall buildings

Cited by 39 publications

References 13 publications

Seismic Shear Forces in Shear Walls of a Medium-Rise Building Designed by Response Spectrum Analysis

Seismic Shear Forces in Shear Walls of a Medium-Rise Building Designed by Response Spectrum Analysis

A modified response spectrum analysis procedure to determine nonlinear seismic demands of high‐rise buildings with shear walls

Evaluation of Seismic Shear Demands of RC Core Walls in Thailand Determined by RSA Procedure

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