Seismic Optimum Design Of Small And Medium Span Bridges In Mountainous Areas

The western mountainous areas are in high intensity area, there are many high mountainsand deep valleys, and the terrain is very complex, so seismic design of the bridge inmountainous areas is quite different from seismic design of the bridge in plain area. Althoughthere are many construction practices of bridge in mountainous areas both at home and abroad,the research on influence of different bearing types and different pier types on bridge seismicperformances is very little.With reference of the damage of common bearing and pier both at home and abriad, theauthor summarized its causes and forms in this paper. The documents about effects ofdifferent bearing types and different pier types on bridege earthquake responses both at homeand abroad were also reviewed in this paper. In addition, the author summarized relatedearthquake-resistant calculating mechanism and unit simulation system, too.In view of three different combinations of bearing types, named the combination ofskateboarding bearings and plate bearings, the combination of all use of plate bearings, andthe combination of activities pot rubber bearings and fixed basin-type rubber bearings, usingMidas software, the author established finite element models of five span continuous bridgescontained three combinations of bearing types. To do static analysis, the author computed thecrack width of pier in use and the ratio of positive cross-sectional axis force and eccentriccompression of three combinations of bearing types. To do dynamic analysis, the authorcomputed the strength of piers, seismic capacity of bearings, the capacity of plastic hingetransfers to plastic rotation of three combinations of bearing types. The differences betweenthem indicate that the combination of activities pot rubber bearings set on abutment and fixedbasin-type rubber bearings set on piers is recommended, because the moment and shear forceof piers of this combination is less than that of the other two combinations.In view of three different combinations of pier types, named the combination of all useof rectangular hollow piers, the combination of all use of two-column piers, and thecombination of rectangular hollow piers and two-column piers, using Midas software, the author established finite element models of five span continuous bridges contained threecombinations of pier types. The static and dynamic performances of bridge are verified, theauthor also do some comparative analysises of static and dynamic performances of threecombinatios of piers. The differences between them indicate that the combination of all use oftwo-column piers is recommended, because the moment and shear force of piers of thiscombination is less than that of the other two combinations.In summary, activities pot rubber bearings should be set on abutment, fixed basin-typerubber bearings should be set on piers, and two-column piers should be used.