Abstract: Based on the semi-rigid joint experiment,it was gained the formula of initial torsion stiffness R_k and bolt tightening moment T of right-angle coupler.On the basis of considering semi-rigid joint,it is indicated that it is rational to use imaginary horizontal force of 0.1% stability capacity in every joint to simulate initial imperfections of the frame by finite element software.Combining with the contrast of finite element analysis results and experimental results,it is the prerequisite to calculate stability capacity exactly with semi-rigid joint of falsework considered.At the same time,the descending trend of stability capacity of the falsework was evident when tightening torques of the couplers is less than 30 Nm.Therefore,during the construction process,it is indispensable to sampling inspections of the tightening torques of the couplers strictly.