ANALYSIS OF CONSTRUCTION LOADS ON FORMWORK DURING CONCRETE PLACEMENT BASED ON INFLUENCE SURFACE

Most of disastrous collapses of falsework occurred in concrete placement period. During concrete placement, falsework is subjected to a large proportion of construction loads which can not be described as uniform distribution loads in the view of statistics. In this paper, in terms of extending the conception of influence line from a 2D structure to a 3D falsework system, the influence surfaces of axial forces for a vertical bar of falsework are obtained using the Kinematic Method, and the characteristics of influence surfaces are investigated. The influence surfaces are fitted by some functions and equivalent heights of influence surfaces in positive and negative regions of load effects are given respectively. Survey of construction projects was conducted. Based on the characteristics of influence surfaces and collected data, the characteristic values of a concrete load, a construction live load and a large construction equipment load are presented. The research result can fill in the blank of design code for falsework in China.