Investigation On Dynamic Characteristics And Anti-collapse Of Coupler-style Steel Tubular Formwork Supports

Coupler-style steel tubular formwork supports has become the most widely used in china as a mold form because it has a number of advantages:ease of installation,applicable to a wide range,low expense,high capacity and overall stiffness,etc.However,the safety of coupler-style steel tubular formwork supports is not given sufficient attention, and many collapse accidents occurred in the last ten years,caused serious threat to the safety of building production.A reason is that the comprehensive study and understanding of coupler-style steel tubular formwork supports system has still not be built.Hence,the investigation on coupler-style steel tubular formwork supports has important theoretic and practice value.Based on analyzing the composition of coupler-style steel tubular formwork supports and the reason of lots of collapse accidents,this thesis clearly discussed the dynamic mechanical behavior and the stable load of formwork supports in the case of considering the semi-rigid characteristics of coupler connections.The main findings are as follows:(1)The large general-purpose finite element analysis software was used to build the three-dimensional member finite element models in this research,the semi-rigid relationship of coupler node use the moment-rotation relation which was established from the preliminary study by discussion group. The numerical simulation characterized by material nonlinearity and geometrical nonlinearity and theoretical calculation is carried out,through comparative analysis,which are used to investigate the effect of erection of structures in different conditions,different periods in construction on the mechanical behavior of high formwork supports system.Thus it obtained the quantitative model considering various factors on the dynamic characteristics of formwork supports.(2)Pump pipe pulse power will cause the vibration and the instability of the formwork supports system.This research had done the mechanism analysis on pump pipe pulse power and presented a simplified design equation.And the FEM analysis was used to analyze the dynamic response of formwork supports under the force of pump pipe pulse power. The formula and conclusions provide a reference for engineering practice.(3)Collapse accidents of formwork supports often happened. Another important reason is the insufficient load-carrying capacity of the support.This research had done a FEM simulation Through two aspects:structural factors of formwork supports and the different casting paths of concrete.And the way and the extent of the impact of various factors on the stability capacity of formwork supports was shown.On this basis,this research gives some useful suggestions about scaffold erection and the choice of casting paths of concrete.