Experiment And Research On The Control Of The Collapse Of The Prestressed Steel Reticulated Shell Structure By The Casing Member

At present,there are few studies on the continuous collapse control of large-span spatial structures.The indirect design method and the direct design method are two common methods for the design and analysis of large-span spatial structures against continuous collapse.The indirect design method is a conceptual design method by constructing the redundancy and robustness of the reinforcement structure to improve the ability of the structure to resist the collapse of the structure.The direct design method mainly includes changing the force path method(AP method)and key components.law.However,for the large-span spatial structure with outstanding stability problems of prestressed steel reticulated shells,these two design methods can not completely solve the characteristics of poor ductility and low energy consumption during structural collapse caused by brittle instability of the main compression bars.The casing member is a structural instability sensing and control member,and is also a new anti-buckling support applied to the space steel grid structure;the sleeve member is applied to the appropriate position of the prestressed steel reticulated shell structure,which may be It is more effective and more direct to control the collapse of the structure under the condition of changing the original reasonable force performance,maintaining the beautiful structure and not increasing the amount of steel.In this paper,the material constitutive model of prestressed steel reticulated shell structure(tetragonal pyramidal twisted net shell structure)and the collapse control mechanism of casing member on quadrangular pyramid twisted net shell structure are studied.At the same time,the casing member is twisted into four corners.The experimental research on the collapse control of the reticulated shell structure has mainly completed the following aspects.1)Applying the spatial reinforced constitutive model of the beam-column unit,the damage accumulation and rate correlation characteristics of the material under dynamic impact load are introduced into the material constitutive model to establish the material damage accumulation considering the space beam-column unit.A hybrid enhanced constitutive model with material-rate related properties.The correctness of the hybrid strengthening model is verified by the continuous collapse analysis of the square pyramid twisted reticulated shell structure.The stress-strain curve of a single circular steel tube under constant amplitude displacement loading is used to verify the correctness of the steel damage cumulative constitutive model.The yield strength of the circular steel tube at different tensile rates verified the correctness of the constitutive model of the steel rate-dependent properties.2)The lower prestressed cable is the key component of the quadrangular pyramid-twisted reticulated shell structure(high-sensitivity rod).The lower prestressed cable is selected as the initial failure rod.The teragonal taper reticulated shell structure is applied by LS-DYNA software.The internal force redistribution and collapse control mechanism of the prestressed cable at the lower part of the casing member suddenly breaks the residual reticulated shell structure,revealing the collapse control mechanism of the casing member to the reticulated shell structure.Firstly,two casing members were applied at different positions of the reticulated shell structure.The dynamic collapse process after the cable-shell structure of the casing member with different positions was applied was analyzed,and the optimal casing member placement position of the reticulated shell structure was obtained.Then,after applying the casing member at the optimal casing member placement position of the quadrangular pyramid twisted reticulated shell structure,the parameters of continuous collapse load,lower prestressed cable cross section and two different material constitutive models are studied.The influence of the casing member on the continuous collapse control of the reticulated shell structure after the reticulated shell structure is removed.3)The test model of the collapse control of the four-corner torsion net shell structure of the casing member is designed.The size of the reticulated shell is 7.2m×7.2m,the thickness of the reticulated shell is 1.55 m,and the cantilever is 2.545 m.Stress cables are provided for easy testing.Using the principle of lever and electromagnetic,a cable breaking device that can effectively simulate the transient failure of prestressed cable is designed.The test of the cable breaking device shows that the cable breaking device can realize the instantaneous failure of the prestressed cable,and the disconnection of the cable breaking device can be realized by remotely controlling the electromagnet power switch of the cable breaking device,thus ensuring the reliability of the collapse control test and safety.The sleeve member outer sleeve was designed according to the core size of the sleeve member to have a cross-sectional dimension of 68 mm x 3 mm and a rod length of 1470 mm.The No.III casing member was applied to the four-cone twisted reticulated shell structure.The static strain test analysis system and the dynamic and static signal test and analysis system were used to collect the strain and dynamic displacement during the collapse control of the reticulated shell test model.The results and finite element simulation results further reveal the continuous collapse control mechanism of the casing member to the quadrangular pyramid twisted reticulated shell structure,and verify the accuracy of the numerical simulation of the continuous collapse control of the quadrangular pyramid twisted reticulated shell structure based on LS-DYNA software.And feasibility.