Research On Dynamic Characteristics Of Special Truss Moment Frames With Vierendeel Web Members

The economic span of traditional frameworks is generally not more than10m.When span continues to increase will lead to negative economics. If we use steel trusses to take the place of solid-web girders in tradional steel frames is called truss moment frames. To set energy dissipation segment of a weak shear capacity near the mid-span of trusses, and make the structure produces plastic hinge. This change is good enough to increase the ductility of the structure, reduce the input of seismic energy。 The new type of structure can save material, construction time, achieve the stratification of industrial workshop in the large span and multiple building requirements. The structural system has a very important significance in save land and reduce costs. Due to the structure is partial flexible, it has a large span and low sensitivity in seismic action. So the dynamic characteristics of this system is different from the traditional frame structure and it is very necessary to develop the research.This paper designed the five series of truss frame structure are analyzed through modal analysis by using the finite element software ANSYS, mainly discussed the varying pattern of period and frequency, such as stories of the structure, the length of the energy dissipation segment, the panel’s depth-width ratio, the number of spans and the vertical height of truss. Through the stage of elastic response spectrum can analysis from the stories of the structure, the energy dissipation length, the number of spans to discusses the varying patterns of the story lateral displacement and the inter-story displacement rotation in truss moment frames.Modal analysis and response spectrum analysis indicate that the natural period increased and the frequency of structure decreased with the increase of the layers and the energy dissipation length. The panel’s depth-width ratio, the number of spans and the vertical height of truss have no significant effect in period and frequency. For the truss moment frames and energy dissipation length of3m, the lateral displacement curve is a shear-type structure, and the maximum layer displacement angle appears in low part of the floor. The displacement curve of special truss moment frames is a type of flexible-shear structural for the energy dissipation length of6m and9m. It is proved that the maximum layer displacement angle of the station appears in the central floor. All specimen of the inter-story displacement Angle conform to the requirement of seismic codes in elastic stage.The elastic response spectrum analysis and elastic time history analysis under the influence of the three types seismic waves is carried out for the ninth floor model. The results show that some different between two methods of analysis. It is very necessary to complementary calculations using time history analysis under the frequent earthquake. Finally contrast between the bottom of the shear, both are conform to the requirements of the seismic code.According to the results finite element analysis, the characteristics of special truss moment frames with vierendeel web members are studied, and provide a reference for elastoplastic dynamic analysis in the future. Finally, considering the limitations of the study and future research,it points out some suggestions.