Calculation Method And Uncertain Analysis On Structure Performance Of Random Friction Loss For Suspend-Dome

As a new type of hybrid space structure,the suspend-dome is widely used in the long-span spatial structure due to its high structural efficiency and convenient construction,however,the prestressed friction loss inevitably existing during the process of tensioning hoop cables would reduce the bearing capacity and even threaten the security of the structure.Based on probability statistics and according to the random variation characteristics of friction coefficients at the cable-strut joints of the suspend-dome structure,this paper systematically studied the value-picking method of friction coefficients,the accurate simulation of random friction in the whole structure and its specific effect law on structure performance.The main research work of this paper is as follows:(1)Based on elastoplastic mechanics and finite element theory,a three-dimensional equivalent friction element suitable for suspend-dome structure is proposed.The finite element analysis format of the element is established,and it is assembled into the overall stiffness matrix and load array of the structure to complete the sliding friction process at the cable-strut joints.The applicability of the friction element is verified by theoretical derivation and numerical calculation,the finite element analysis of suspend-dome structure considering friction loss is realized.(2)Based on the basic principles of tribology,a cable force calculation method considering unequal tensioning control force and random prestressed friction loss was proposed,and it was introduced into the force-finding process of the suspend-dome structure,the reliability of the method was verified by tension test results.The internal force distribution of each cable segment during the tension construction of the suspend-dome structure is accurately determined.It was found that the cable force of the same tensioning cable approximately shows a linear decrease from the tensioning points to the middle parts of the tensioning cable.And the smaller the prestressed control value is,the higher the calculation accuracy is.(3)Types and values of friction coefficients at the cable-strut joints in constructed engineerings and tests were extensively investigated,and based on probability statistics,a stochastic mathematical model of friction coefficient at the rolling cable-strut joint was established.It was found that the friction coefficients at the cable-strut joints are highly variable.The variability of friction coefficient obtained by the on-site monitoring is higher than that obtained by the experiment,and the friction coefficient at the joint increases with the cable force.The rolling cable-strut joint can effectively decrease the friction coefficient,and the stochastic mathematical model of the friction coefficient at the rolling-type cable-strut joint has certain reliability.(4)By using Monte Carlo method,the stochastic mathematical characteristics of the mechanical properties considering the random prestressed friction loss of all joints were simulated and analyzed,the results of uncertain analysis on structure performance were verified by results of static loading experiment.A numerical model considering various random defects such as friction loss,member initial bending,and joint installation deviation was established,the effect law of random defects on the structural ultimate bearing capacity was studied.It was found that the joint vertical deformations and member axial stresses are sensitive to friction coefficients at the adjacent cable-strut joints,and the joint vertical deformations are sensitive to the friction coefficients of the outermost hoop cable.Random prestressed friction loss will greatly affect the static performance of the suspend-dome structure,which reduce the prestressing effect and the structural ultimate bearing capacity.