Study On Seismic Damage Performance Of Long Span Rigid Frame Bridge In Deep-water Based On IDA Analysis

With the rapid development of transportation industry in our country, an increasing number of continuous rigid frame bridge have been sprung up, especially in the southwest and northwest area with complex and changing terrain in our country. With its obvious economy, applicability, safety and aesthetics, long span continuous rigid frame bridges are widely used, and have been an important form of long span deep-water bridge. However, at present, the earthquake damage characteristics of long-span rigid frame bridge, especially deep-water rigid frame bridge, also need to be studied. Taking a long span deep-water bridge with continuous rigid frame as engineering background, groups of strong earthquakes are selected, by IDA analysis method, the probability damage state of rigid frame birdge in different water depths is analysed quantitatively. The main research contents are as following:(1) The rigid frame bridge models with different water depths(0m,12m,27m) are built by OpenSees finite element software, taking into acount the pier-soil interaction and dynamic water pressure of pier, the influence degrees of hydrodynamic effect to the natural characteristics of deep-water bridge are analysed.(2) Selecting 12 seismic waves which peak ground acceleration (PGA) increase gradually from 0.05g to l.Og, the rigid frame bridge under condition without water is analysed by IDA analysis method; by drawing the IDA curves of pier head and pier bottom curvature and bearing displacement, the distribution characteristics of IDA curve under different PGA are acquired, and the corresponding 16%,50%,84% percentile curves are achieved. According to the exsiting classification of damage grade, the damage states of pier and bearing under different PGA are assessed.(3) By analysing the rigid frame bridge with 12m and 27m water depths, the IDA curves of pier bottom and bearing displacement are drawn; comparing the damage states of pier bottom section in different water depths under different PGA, the inside and outside pier bottom curves increase with the increasing of water depths, and pier bottom section is destroyed earlier with the increasing of water depths. With the increasing of water depths, the displacement of bearing increase slightly under the same earthquake motion intensity(4) According to existing IDA analytic data, the fragility curve of damage states at all levels of inside and outside pier bottom and bearing with different working conditions are acquired. The exceedance probability of damage states at all levels for inside and outside pier bottom and bearing increase with the increasing of PGA. With the increasing of water depths, the exceedance probability of damage states at all levels for inside and outside pier bottom increase obviously, and the exceedance probability of damage states at all levels for bearing also increase slightly.