Precast segmental bridge columns with resettable sliding joints —— An inspiration from ancient Chinese pagodas

Abstract

The construction of bridge substructures by in-situ assembly of precast concrete segments provides significant benefits in quality control and economy, but their seismic stability is always a concern. Incidentally, prefabricated components have long been used in building tall pagodas for thousands of years in China. Among the pagodas that have survived numerous centuries, the timber pagodas are believed to be assembled structures of great research value in respect of seismic isolation design. There is indeed a certain degree of similarity between the timber pagodas and the proposed precast segmental bridge columns with resettable sliding joints. The smart seismic isolation mechanism in multi-storey timber pagodas with mortise-tenon rocking columns and distributed bracket sets has the following key features: (a) high lateral flexibility, (b) smart energy dissipation system, (c) guided self-centring behaviour, and (d) measures to enhance vertical stability. Actually, the resettable sliding joints in the present precast segmental bridge columns are so designed and distributed to obtain a similar seismic isolation mechanism. Time-history simulation results of seven conceptual models show that the columns with resettable sliding joints outperform the other counterparts especially in respect of (a) the overall seismic isolation between the top mass simulating the deck and the shaking ground, (b) the control of residual sliding displacements at segment interfaces, and (c) satisfactory energy dissipation performance.