Analysis Of Portal Frame Reduction Of Space Truss Structures With Viscous Dampers

Due to absorbing excessive earthquake energy, some members in traditional structures may enter into elastic-plastic state, even yield or fail under strong earthquake, with a consequence of repair failure later or direct collapse. Dampers added to structures are responsible for consuming energy introduced by earthquake or other dynamic inputs.Dampers added to structures are responsible for consuming energy introduced by earthquake or other dynamic inputs. The supplemental energy dissipation systems can be used to control story drift, improve or upgrade the structural seismic performance of new or existing building. This technique has been becoming one of the main tendency of earthquake-resistant engineering research. Scholars and engineers of this domain in many countries are being engaged in this field of research and practice.A direct numerical integration of the equations of motion is a general method for analyzing damper-added structures. The motion equations of damper-added structures and the dynamic time-history analysis procedure are discussed in detail. The procedure can solve a SDOF system, a MDOF system, a system considering torsional responses, or a three-dimensional finite element system. The paper uses Fast Nonlinear Analysis to solve problems which is suitable for local nonlinear problems. The method is mentioned above is more effective and pricise. And the fast nonlinear analysis (FNA) method in the program SAP2000 that has been expatiated in the thesis.The use of the portal frame structure of energy dissipation were studied,including the structure calculation of energy dissipation model and calculation method, modal analysis, structure dynamic property, arranging energy dissipation mechanism, damping coefficient optimization, the structure damping with different frequency characteristics of seismic wave,etc. The modal analysis indicates that the dynamic characteristic of space truss structure is complex, and the vibration mode of the model is mainly vertical and horizontal. The effect of restoration is little.By considering six different setting manners of viscous dampers, analysis of damping effect is carried out.With no control of the structural dynamic response were compared, ultimately through the analysis of calculation and comparison ,it is found the better damper layout.By considering different damping coefficient and number of viscous damper and different seismic wave, analysis of damping effect is carried out in the paper too. The result indicates that the damping coefficient and number of damper have optimal values. That offers a good reference for engineering designers. The structures'responses maybe have larger difference under different seismic waves. In order to get more accurate results, using many seismic waves to calculate and taking their average are necessary.