Explicit fiber element and its application to piers under multipulse near‐fault earthquake motion

摘要

The time delay effect is prominent for the slender structures under the action of near-fault pulse-like earthquake excitation. It takes time for the earthquake motion to transfer from the base to other portions of the structure. This paper proposes an explicit-based fiber line element with its analytical framework to capture the time delay effect when excitated by earthquake motion. The object-oriented technique (C++) is used to code the integrated analysis framework. Newly designed classes are integrated to perform the explicit analysis parallelly. The nonlinear material model is also incorporated into the proposed element. The verification of the proposed element shows the time delay effect can be spotted inside the structure. The proposed element can provide a reasonable transient dynamic response under both static and dynamic loadings. The basic and higher vibration model can be aroused if the proper frequency is inputted. A slender reinforced concrete bridge pier is numerically modeled by the proposed element, and its seismic response characteristic under the action of the qualified multipulse near-fault earthquake motion is analyzed. The results show the seismic response within the pier is transferred from bottom to top in a distinct time delay. In a statistical sense, the typical increasing ratio of relative displacement for S/R and P/S is 4.9% and 8.1%, respectively. Directly using the earthquake motion recorded at the seismic station may underestimate the seismic demand.