Experimental Study On Formwork Support System Under Staggered Arrangement Of Support Frame

In recent years,with the rapid development of urbanization,the owners have more and more stringent requirements for the construction period,so that the interval time between the completion of concrete pouring,so the multi-layer formwork support system came into being.But the staggered erection of the upper and lower layers of the support stand does not meet the requirements of relevant codes,such as JGJ231-2010 safety technical specification for building construction and socket-type steel pipe supports 7.4.7: when formwork supports are arranged continuously on a multilayer floor,the upright pole of the upper and lower layers shall be guaranteed to be on the same axis;GB50204-2015 code for acceptance of construction quality of concrete structure engineering 4.2.8: the multi-layer continuous formwork of cast-in-place concrete shall conform to the stipulations of the scheme,and the vertical bar of formwork supports in the upper and lower layers shall be aligned.Considering that the construction period is short,the concrete after pouring shall bear the construction load of the upper structure.Therefore,it is important to study the force and axial force transfer law of floor and support frame of the construction period to ensure engineering quality and construction safety,the research contents of this paper are as follows:(1)Selection of the actual engineering project of three layer support Raffles(L11,L12,L13)and the two floor as the test object,carried out to consider the field test of the formwork support frame staggered arrangement under the state support,according to the analysis of the test data of each layer of support pole axial force variation,grouping for different(staggered distance a total of six groups),by comparing the distance staggered increases,the axial force transfer efficiency is poor,mean the floor staggered between to withstand greater force;(2)Study on the slab steel tension(compression)relationships between the stress and the change of the axial force of vertical strut and change of both time and space,analysis results show that with the age of concrete strength and elastic modulus increase,steel tension(compression)stress increases gradually,and the supporting frame vertical rod axial force decreases gradually,gradually began to reflect the floor bear the construction load phenomenon;(3)Based on the analysis of experimental data,select the most unfavorable conditions,through the finite element analysis software Abaqus,the range and depth of influence support pole staggered arrangement on the floor,and the measured reinforcement stress values were compared with the simulation,and analyze the reasons of error.