|Statement||by Panos Trochalakis, Marc O. Eberhard, John F. Stanton.|
|Contributions||Eberhard, Marc O., Stanton, J. F., Washington State Transportation Commission., United States. Federal Highway Administration.|
|The Physical Object|
|Pagination||iv, 39 p. :|
|Number of Pages||39|
Unseating of Simply Supported Spans During Earthquakes Author: Bridge piers, Bridge superstructures, Bridges, Dislocation \(Geology\), Earthquake resistant design, Earthquake resistant structures, Evaluation, Mathematical models, Measures of effectiveness, Nonlinear systems, Prestress\ ed concrete bridges, Prevention, Retrofitting. COVID For the latest COVID health guidance, statistics and resources, visit During earthquake shaking, pounding of decks occurs in multi-span simply supported bridges (MSSS) when relative displacement between two adjacent decks exceeds the available expansion gap. It may cause the failure of a bridge in various ways such as unseating of the deck, pier failure, bearing failure, and local damage to decks and : Lopamudra Mohanty, Rahul Das, Goutam Mondal. A six-span simply-supported bridge with rigid bearings and multiple unseating prevention devices (restrainer and stopper) is analyzed under near-field ground motions recorded at JR Takatory and JMA Kobe during the Japan Kobe earthquake.
One of the most frequent modes of failure of these bridges was the unseating of their simply supported spans (Saiidi et al. ). The problem becomes more intense when the gaps between the. The collapse of bridges due to unseating at intermediate (in-span) hinges during recent earthquakes emphasizes the need to provide an adequate number of restrainers to limit the relative displacement between frames in a bridge with inadequate hinge seat width. Maintaining a sufficient support length at abutments, piers, or in-span hinges of bridges is essential to preventing span unseating during earthquakes. Hence, minimum support length (MSL) is always the primary consideration in the seismic design of bridges, which has been extensively specified in modern bridge codes. Failure of girder ends and bearing damage due to pounding of adjacent simply-supported spans were reported after the Bhuj earthquake in Gujarat, India. Pounding damage between adjacent bridge structures were also observed in the Wenchuan earthquake , Chile earthquake  and more recently in the Christchurch earthquake.
The multi-span bridge considered in this analysis consists of three spans supported on multi-column bents, as shown in Fig. 4. Each bent has four columns and each span has 11 girders. The span lengths are m (40 ft), m (80 ft), and m (40 ft), and the width is m (64 ft). Keywords: composite, bridges, unseating, behavior, analysis, bearings 1. Introduction Bridge bearings are crucial components of highway networks and require both corrective and preventative maintenance actions. The author has presented a study for the effect of bridge girders unseating for a simply supported composite bridge. during earthquakes. The collapse of the Gavin Canyon Undercrossing and the 14/5interchange during the Northridge earthquake has proven the inadequacy of the currently used steel restrainers (Saiidi et al ). A number of other devices have been presented in the past two decades as unseating prevention devices for bridges, such Figure 3. bridge to deck unseating during the same earthquake shaking. for which the bridge spans are still. to prevent unseating in simply supported bridges subjected to strong earthquakes were.