Spatial And Temporal Analysis Of A Long Span Frame Structure And Its Multi-storey Formwork Support System During Construction

The cast-in-place concrete frame structure and its multi-storey formwork supports system is a time-varying structure, load and internal force of this structural system is changing with time.The strength of the cast-in-place concrete is still in development period and low,makes the system is in a higher structure failure probability and safety accident risk structure, safety accidents occur easily during construction,and study on cast-in place frame structure and its multi-storey formwork supports system helps to ensure the safety of construction.This thesis takes a long span frame concrete building and its multi-storey formwork support system as the object;with the system, this paper study its time-varying characteristics of the load and resistance.The main content is presented as follow:(1)Combined with a project of the long span frame concrete building,a survey on live loads of this building during construction has been conducted.Based on the data of the survey,the mathematics model of live loads was proposed with mathematics statistics analysis,submit to exponential distribution.And the standard values of live loads during construction was also brought forward2/0.3 mk N at last.(2)The characteristics and limitations of the two kinds of analysis methods are compared and summarized:continued beams with elastic bearing and its its improved model,and elastic plate mode.Load distribution and transfer of the concrete frame structure and its muli-storey formwork support system during construction were studied.The stress pole stress of the support system were measured in-site,and the loadvariation of the support system were got,the load distribution between the concrete floors and its support was with their rigidity.After the concrete pouring is completed,the load transferred 40%~50% to next floor and 10%~15% to the third floor.The stress changes of bars of the tie member during construction was recorded, the stress of the bars in different direction and different position is different,the tie members in high position play a better role to fastening support system than the lower position,and the maximum tensile stress of the bars is 22.1MPa,and the maximum compressive stress is61.2MPa.(3)This paper has carried on calculation analysis of the long span concrete frame structure building and its nulti-storey formwork support system,and has set the model with the SAP.With the time freezing method,the load’s parameters of specific time were used as analysis variables,and got the load variation law by analysis different kinds of work condition,the time varying characteristics of the system has been validated by contrasting calculation and measured data,the law of load variation similar to the field test results was obtained.