Seismic Response Analysis Of Simple-Supported Skew Highway Girder Bridges

The complexity and peculiarity of seismic response of skew bridges cause itsearthquake-vulnerability. Current codes of seismic design for highway bridges inmain earthquake countries have not given a utility seismic design method for skewhighway bridges. Therefore, studying on seismic design theory for skew highwaybridges, to propose a simplified seismic response calculation theory for skew highwaybridges which solve the difficult problem met in seismic design of skew highwaybridgesbuiltin highlyearthquake zones is a pressing work. In this paper, the state-of-the-art of earthquake resistance study on skew highwaybridges is reviewed firstly. Then, parameter analysis of seismic response ofsimply-supported skew highway girder bridges is performed based on theachievements of researchers. In the analysis, skew angle, stiffness of bearing, spans,height of pier and number of span are considered as variable parameter, respectively.The conclusions drawn from the analysis are as follows: 1. For single-span simple-supported skew highway girder bridges, the effects ofskew angle, spanand support stiffness of bearing on seismic response of the structuresare studied. The results fit with the achievements of foreign researches satisfactorily.It is concluded that seismic design force and displacement of single-span highwayskewed girder bridges canbe calculated according to relative straight bridges. 2. For two and three-span skew highway girder bridges, the effects of skewangle, height of pier and span on seismic response of the structure are thoroughlystudied. It is found: 1) When the earthquake motion is inputted in X direction (vertical axis of bentcolumn) and skew angle is less than 30 degree, skew angle has little effects on theseismic internal forces at the feet of piers and the displacements of girders, But ifskew angle exceeds 30 degree, then seismic internal forces at the feet of piers anddisplacements of girders are increasing with the skew angles. Furthermore, the higherthe piers are, the larger increasing effects are. When the earthquake motion is inputtedin Y direction (parallel axis of bent column), skew angle has little effects on the IIIseismic internal forces at the feet of piers and the displacements of girders. 2) The height of piers is an important parameter for seismic response of skewhighway bridges. When the earthquake motion is inputted in X direction, the internalforces at the feet of piers and displacements of girders are increasing with the heightof piers. Moreover, the higher the piers are, the more obviously the effect is. At thecase of skew highway bridges with higher piers and larger skew angles, thedisplacements of superstructures can be two times as large as the displacements ofrelative straight bridges. When the earthquake motion is inputted in Y direction, thehigher the piers are, the larger the seismic internal forces at the feet of piers anddisplacements of girders are. 3) Span is another important parameter for seismic response of skew highwaybridges. When earthquake motion are inputted in X direction and Y direction,respectively, seismic internal forces at the feet of piers and displacements of girdersare bothincreasingwith the span. 3. For simple-supported skew highway girder bridges with more than three spans,the effects of the number of span on seismic response of the structure are studied. Ifthe earthquake motion is inputted in X direction , the internal forces at the feet ofpiers of middle spanare increasing with the number of span, but the internal forces atthe feet of piers of side spans are decreasing with the number of span. Furthermore,the displacement of the girder of middle span doesn't change obviously with thenumber of span, but the displacements of girders of side-spans are decreasing with thenumber of span. The number of span has little effect on displacements of the girdersand internal forces at the feet of piers when...