Demands on nonstructural components in buildings with controlled rocking braced frames

Abstract

Controlled Rocking Braced Frames (CRBFs) have been developed as a high‐performance seismic force resisting system that can self‐center after an earthquake and avoid structural damage. A CRBF is designed to uplift and rock on its foundation, and this response is controlled using prestressing and energy dissipation devices that are engaged by uplift. Although CRBFs have been shown to have desirable structural performance, a comprehensive assessment of this system must also consider the performance of nonstructural components, which have a significant impact on the safety and economic viability of the system. The purpose of this paper is to evaluate the demands on nonstructural components in buildings with CRBFs in comparison to demands in a reference codified system, taken here as a buckling restrained braced frame (BRBF), as well as to identify which design parameters influence these demands. The responses of various types of nonstructural components, including anchored components, stocky unanchored components that slide, and slender unanchored components that rock, are determined using a cascading analysis approach, where absolute floor accelerations generated from nonlinear response history analyses of each system are used as input for computing the responses of nonstructural components. The results show that the downside of maintaining elastic behavior of the CRBF members is, in general, larger demands on nonstructural components compared to the BRBF system. These demands are not highly influenced by impact during rocking or by the supplemental energy dissipation provided, as the vibration of the CRBF in its higher modes is primarily responsible for the higher demands.

Seismic pounding damage to adjacent reinforced concrete frame–shear wall buildings and freestanding contents

“…Only the horizontal DOFs were considered in the dynamic analysis with floor masses lumped at the nodes of the Euler beam elements, and the rotational DOFs were statically condensed. While the $$P-\Delta$$ effect may be introduced using a leaning column, 29 it was insignificant (see Section 5) and was therefore not implemented in the OpenSees model. For simplicity, the stiffness values were assumed to be uniformly distributed along the building.…”

“…This record set is a robust sample of all strong motion records obtained from events dominated by shallow crustal earthquakes with magnitude ranging from M6.5 to M7.6, recorded at sites greater than 10 km away from fault rupture. We followed the scaling procedure suggested by Buccella et al 29 and used a single scale factor of 1.073 for all 44 ground motions in order to match their median spectral shape with the maximum considered earthquake (denoted by MCE with a 2475-year return period) acceleration spectrum (considering a shaking intensity of level VIII for seismic design) suggested by the Chinese code for seismic design of buildings (GB50011-2010), 48 as presented in Figure 5. Then, the design earthquake (DE) ground motions were obtained by multiplying a factor of 2/3 to the MCE ground motions according to the ASCE/SEI7-16 standard.…”

“…A prominent feature of seismic pounding between adjacent buildings is the introduction of acceleration spikes into floor motions due to impacts that may occur multiple times in the duration of shaking. Several studies have addressed the influence of impacts (due not to structural pounding) on sliding and rocking BCs 25,29–31 . Buccella et al 29 .…”

“…Several studies have addressed the influence of impacts (due not to structural pounding) on sliding and rocking BCs 25,29–31 . Buccella et al 29 . assessed seismic demands on sliding and rocking BCs with controlled‐rocking‐braced frames with column uplifting and impacting against ground during rocking.…”

“…Several studies have addressed the influence of impacts (due not to structural pounding) on sliding and rocking BCs. 25,[29][30][31] Buccella et al 29 assessed seismic demands on sliding and rocking BCs with controlled-rocking-braced frames with column uplifting and impacting against ground during rocking. No significant spikes were observed in the floor acceleration histories, and the dynamic response of the BCs did not exhibit noticeable changes upon impact.…”