Displacement-Based Seismic Design Of Space Grid Structures

With the development of the economy and constant progress of science and technology,application of grid structures in buildings is more and more extensive.The double-layer space grids is a space pole structure of grid shape.It's structure members is disposed according to the certain rule and connected by nodes.It has many advantages,for example large span,large rigidity,good stability,secure and reliant,finer aseismatic performance,extensive adaptability,industrialized ect.Grid structures belong to statically undetermined structure so it's very difficult to analyze its mechanical performance,entirety and stability.After 1976,people adopt double-layer space grids as roof of industry workshop and public building.However,how to perform seismic design of double-layer space grids is still an important problem concerned.Convenient, reasonable choice of design performance targets are based on the displacement of a seismic design advantages.As displacement (or deformation) than the strength (or capacity) of the earthquake can better embody the role of performance, thus directly control structure designed to shift the seismic design method than the current seismic design based on the strength of a more simple way, in terms of concept Also clearer, more conducive to the realization of performance-based seismic design concept.There are two steps to design a structure according to the seismic code, design the structure according to the bearing capacity at first, then check the deformation of the designed structure.However, in the direct displacement-based seismic design, the displacement is the controlling parameter and it can control the action of the structure under the earthquake action.This paper recalled the development process of structure seismic design theory,introduced the concept and design steps of displacement-based seismic design at first. In This paper ,The grid structure with the largest displacement and the grid rods damaged as a double-level control targets to achieve the grid structure of the seismic performance targets.And then, the method (direct displacement-based seismic design) was used for a space grid structure design.Through examples of projects that use grid structure of the grid with the largest displacement and the grid rods damaged as a dual-level indicator, the special-shaped truss structure based on the displacement of the seismic performance of the design is a practical approach.