tailieunhanh - Piers and Columns

Piers and Columns Jinrong Wang URS Greiner 27 Introduction Structural Types General • Selection Criteria Design Loads Live Loads • Thermal Forces Design Criteria Overview • Slenderness and Second-Order Effect • Concrete Piers and Columns • Steel and Composite Columns Introduction Piers provide vertical supports for spans at intermediate points and perform two main functions: transferring superstructure vertical loads to the foundations and resisting horizontal forces acting on the bridge. Although piers are traditionally designed to resist vertical loads, it is becoming more and more common to design piers to resist high lateral loads caused by seismic events. Even in some low seismic areas, designers are. | Wang J. Piers and Columns. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 27 Piers and Columns Jinrong Wang URS Greiner Introduction Structural Types General Selection Criteria Design Loads Live Loads Thermal Forces Design Criteria Overview Slenderness and Second-Order Effect Concrete Piers and Columns Steel and Composite Columns Introduction Piers provide vertical supports for spans at intermediate points and perform two main functions transferring superstructure vertical loads to the foundations and resisting horizontal forces acting on the bridge. Although piers are traditionally designed to resist vertical loads it is becoming more and more common to design piers to resist high lateral loads caused by seismic events. Even in some low seismic areas designers are paying more attention to the ductility aspect of the design. Piers are predominantly constructed using reinforced concrete. Steel to a lesser degree is also used for piers. Steel tubes filled with concrete composite columns have gained more attention recently. This chapter deals only with piers or columns for conventional bridges such as grade separations overcrossings overheads underpasses and simple river crossings. Reinforced concrete columns will be discussed in detail while steel and composite columns will be briefly discussed. Substructures for arch suspension segmental cable-stayed and movable bridges are excluded from this chapter. Chapter 28 discusses the substructures for some of these special types of bridges. Structural Types General Pier is usually used as a general term for any type of substructure located between horizontal spans and foundations. However from time to time it is also used particularly for a solid wall in order to distinguish it from columns or bents. From a structural point of view a column is a member that resists the lateral force mainly by flexure action whereas a pier is a member that resists .