THE CAUSE ANALYSIS OF THE DAMAGED LADDER BEAM MEMBERS FOR STAIRCASES AFTER EARTHQUAKE AND REINFORCEMENT DESIGN

Stairs as the building of vertical transport and emergency evacuation under the main channel flow of a building are related directly to the normal function of the building use and safety and security of human life,whose important role in the overall structural safety should be concerned.This paper analyzes the reasons of the damages the stairs by seism and compares,on the staircase ladder beam strengthening programs,gives the design scheme of strengthening reinforced concrete ladder beam;which can provide some experience for the designers and constructors,thereby enhancing the structural resistance to natural disasters.