Seismic analysis of a modern 14‐story reinforced concrete core wall building system using the BTM‐shell methodology

Abstract

This paper uses computational simulation to investigate the lateral load‐displacement behavior and failure modes of a modern 14‐story reinforced concrete (RC) core wall building. The design complies with the minimum code requirements of the current California Building Code, which is based on ASCE 7–16 and ACI 318–14. The computational representation of the building, which accounts for the material nonlinearities of all structural components, employs the beam‐truss model (BTM) for the walls and floor slabs. Analyses of the building model are conducted for static monotonic and cyclic lateral loads using the program FE‐MultiPhys, which provides a user‐friendly implementation of the BTM as an assemblage of rectangular shell macroelements. Two different load patterns, that is, lateral load distributions along the building height, are considered. The analyses provide insights into the evolution of damage and lateral strength degradation and their dependence on the load pattern, while also elucidating the complex interaction between the webs and flanges of the core wall and the system effects associated with coupling between the walls, beams, slabs, and columns. The presentation of the analytical results is accompanied by a discussion on the advantages of the BTM over seismic analysis methods used in current code‐minimum and performance‐based seismic design (PBSD) practice.

Nonlinear dynamic seismic analysis of a modern concrete core wall building in Los Angeles using the BTM‐shell methodology

“…The nonlinear time history analysis (NLTHA) in this study utilizes a collection of triaxial ground motion records, which are scaled at both the Design and Maximum Considered Earthquake Response (MCE R ) levels. It is important to note that NLTHA is the only and most accurate method used in PBSD practice for design validation, and cannot be replaced by nonlinear static analysis (monotonic or cyclic) such as the one used in Mavros et al 1 The present study provides quantitative specificity to several qualitative conclusions of the work in Mavros et al 1 within the PBSD context, taking into account the effects of multiaxial ground motion on the nonlinear dynamic behavior. The simulation results indicate the critical effect of NLFSI on the evolution and localization of core wall damage and residual deformations.…”

“…BTM, beam-truss model. 1,30,38,39 that includes an implementation of the BTM as a rectangular shell macroelement, termed BTM shell. Each BTM shell is an assemblage of six internal elements, that is, two horizontal, two vertical, and two inclined line elements, as shown in Figure 2B.…”

“…In current PBSD practice, the nonlinear response of floor slabs is not modeled for spans exceeding 6 m. However, Mavros et al 1 showed that due to the significant vertical elongation of the core walls, floor slabs could undergo substantial F I G U R E 1 Crack patterns and failure modes of experimentally tested ductile planar and barbell RC walls. 21 RC, reinforced concrete.…”

“…In Mavros et al, 1 the authors presented a literature review of several shell-based finite element models employed for seismic simulations of RCSW components and building systems. [22][23][24][25][26][27] While an in-depth discussion of this review falls outside the scope of this paper, it is crucial to highlight that none of the examined methods have been validated for all the damage and failure modes discussed earlier.…”

“…The response of the specific building to static lateral loads was considered in a recently published study by the authors. 1 The specific earlier study considered the nonlinear out-of-plane behavior in shear of walls in a simplified fashion, that is, without considering shear strength degradation. The present paper eliminates this simplification by introducing and calibrating a law to account for out-of-plane shear (OOPS) strength degradation of planar wall segments.…”