Dynamic Model And Response Research On Drop Tower’s Cable- Beam System

Drop tower is a commonly used test facility in the special safety drop test at a proper high altitude (dozens of or even a hundred meters). In the progress of drop shock test with drop tower, main steel cable raise beam and weight to a needed height, then release, beam and weight fall, at last beam impacts the stand column, weight falls to the ground. But at a proper high altitude with large wind speed, the beam may goes in a wrong directiom, and deviates from the stand column when reachs the attitude of it, the beam fails to impacts the column and makes guide steel cable broken. This probable test failure mode will impact the testing, so it’s necessarily to study cause and mechanism of it.Firstly, the present research status of the vibration response of high-rise structure and string wire under wind load is summarized, the existing problems and the insufficiency are anasyed, a suitable way is found to research the virbration response of drop tower under wind load in this essay, and research content is put forward.Secondly, on the basis of drop tower’s structure features and test principle, the cable-beam system of drop tower is simplified and dynamical model is built, the string vibration equation is built at different external applied load and speed.Thirdly, the already established vibration equation of the dynamical model related to drop tower’s cable-beam system at cross external applied load is transformed, a usual matrix vibration equation is built. The numerical results of the matrix vibration equation are obtained through programs in MATLAB, they are compared with the results by theoretical method at special conditions to shows the validation of the numerical method.At last, through consulting related architectural structure load standards, considering specific structure features of drop tower’s cable-beam system, mean wind load on the cable and beam is calculated, bringing it to the previous the matrix vibration equation and string displacement response results are obtained with Newmark method, some discipline is found about the displacement response results. As variable parameters in the vibration equation of the drop tower cable-beam system’s dynamical model has influence on the string displacement response under mean wind load, through changing these variable parameters and calculating string displacement response, some regulars is found.