Impact model for simulation of base isolated buildings impacting flexible moat walls

Abstract

SUMMARY Base isolated buildings subjected to extreme earthquakes can exceed their design displacements and impact against the surrounding moat wall. To better understand the consequences of impact on the superstructure, an impact element considering moat wall flexibility is proposed based on impact theory and observations during experimental simulations. It is demonstrated that numerical simulations using the proposed impact element can capture the dominant characteristics of the contact force observed in experiments of base isolated buildings impacting various moat wall configurations including concrete walls with soil backfill and rigid steel walls. The contact force is dependent on impact velocity, geometry, and material properties at the contact surface, and the global dynamic characteristic of the moat wall. Properties of the moat wall impact element are derived based on mechanics‐based models considering material properties and geometric measurements of the experimental setup. For this purpose, the moat wall is modeled as a flexural column with a concentrated nonlinear hinge at its base and soil backfill considered through a damped elastic foundation then generalized into a single degree of freedom system. The resulting impact element is shown to accurately capture both local deformation and the vibration aspects of impact observed in experiments and the effects of impact on superstructure response. Copyright © 2012 John Wiley & Sons, Ltd.

Structural and nonstructural performance of a seismically isolated building using stable unbonded fiber‐reinforced elastomeric isolators

“…This becomes an impact problem if the tangential stiffness of the stiffening regime becomes very large, analogous to pounding against the seismic gap wall [43,44]. Note that at large displacements, a large increase in the restoring force is required to substantially increase k eff and adequately decrease the fundamental period.…”

Influence of the characteristics of isolation and mitigation devices on the response of single‐degree‐of‐freedom vibro‐impact systems with two‐sided bumpers and gaps via shaking table tests

“…The main objective of the applicative and theoretical studies is to examine through numerical simulations and also experimentally evaluate the effects of structural pounding at the base‐isolated level in building structures—which are subjected to strong earthquakes—and the resulting dynamic response of the superstructure.…”

“…Base pounding theoretical models with linear spring‐gap element are proposed in Mavronicola et al and Liu et al whereas Komodromos et al Polycarpou and Komodromos, Masroor and Mosqueda, Mavronicola et al and Liu et al formulate nonlinear impact elements that can simulate the contact force during impact of base‐isolated structure to a moat wall; the moat wall was modeled as either a concrete wall with soil backfill or a rigid steel plate and as two‐sided rubber bumpers …”

“…The results for two‐dimensional MDOF models are discussed in Komodromos et al Polycarpou and Komodromos, Masroor and Mosqueda, and Mavronicola et al whereas three‐dimensional finite element analyses are conducted by Liu et al…”

Performance of base‐isolated reinforced concrete buildings under bidirectional seismic excitation considering pounding with retaining walls including friction effects

“…Because pounding of base-isolated buildings with adjacent structures is likely due to large base displacements, several investigations have been carried out through numerical analyses [1][2][3][4][5][6][7] and experimental studies [8,9]. Because pounding of base-isolated buildings with adjacent structures is likely due to large base displacements, several investigations have been carried out through numerical analyses [1][2][3][4][5][6][7] and experimental studies [8,9].…”