| The disc-buckle type formwork support system has advantages such as strong loadbearing capacity,simple structure,and flexible applicability.In recent years,it has been widely used in high formwork construction.However,as the construction environment becomes more and more complex,the load bearing of the formwork support frame is also complex and diverse,which makes the collapse of the high support frame frequent in recent years,and the research on the collapse resistance and dynamic characteristics of the high support frame has gradually become a research hotspot in the field of formwork support.In this paper,based on the explicit dynamic analysis program LSDYNA,the numerical simulation analysis of the collapse resistance and dynamic characteristics of the coiled high formwork frame is carried out.The main research contents are as follows:(1)According to the erection mode of diagonal bracing in the actual project,four types of rack models,namely symmetrical matrix type,symmetrical plum type,spiral matrix type and spiral plum type,are established for the calculation of ultimate bearing capacity,and the law of rod collapse is analyzed according to the rack collapse mode.Comparing the ultimate bearing capacity,spiral plum type > symmetrical plum type >symmetrical matrix type > spiral matrix type;during the collapse process,the bottom layer of the I-type uprights in the symmetrical frame is the first to be damaged,while the specific location of the initial destabilization uprights in the spiral frame is more random.(2)The transformed load path method(AP method)was used to analyze the dynamic response of the frame under the sudden failure of critical uprights,and the deformation criterion and the bearing capacity criterion were combined to compare and analyze the continuous collapse resistance of four types of frames,comparing the continuous collapse resistance,spiral plummer type > symmetrical plummer type >symmetrical matrix type > spiral matrix type.(3)Analysis of the effect of stiffness and mass load on the self-vibration frequency of the frame shows that the self-vibration frequency of the plume-shaped frame is significantly higher than that of the matrix-type frame;the self-vibration frequency of the frame gradually decreases with the increase of the top mass load,and the first-order self-vibration frequency of the frame under partial load is less than that under uniform load when it is subjected to the same mass load.(4)The analysis of the dynamic response of the rack during the concrete casting stage shows that when the direction of action of the horizontal load of the pump pipe is the same as the first-order vibration type of the rack,the dynamic response of the vertical rod also changes periodically,and the displacement response of the vertical rod is similar to the first-order vibration type;the displacement response of the nodes of the vertical rod increases gradually in the process of the external load frequency approaching the self-oscillation frequency of the rack;when the concrete is cast in Sshape,the maximum internal force of the rack appears in the middle stage of casting,and the action of the horizontal step load during the casting process will change the position of the maximum stress in the rack.(5)Symmetrical matrix type and spiral matrix type frame were selected as the research objects to analyze the dynamic response and dynamic stability of the frame under the action of step load.The results show that the axial response of the vertical step load is affected by the diagonal brace erection scheme,and is different from the static loading,and the dynamic stability of the frame is much smaller than the static stability;under the action of horizontal step load,the dynamic response of the uprights is based on the unit shelf body,and the dynamic stability critical loads of the two shelf bodies are similar,and the position of the initial flexural uprights is mainly related to the way the diagonal brace is erected in the direction of the load action. |
