Compressive Behavior And Design Method Of Gusset Plate Connections For Brace

Seismic has become the main influencing factor on structure safety. How to design a structure resisting seismic load economically is a hot-issue in the field of civil engineering. Due to their large stiffness and good capability of energy dissipating, braced frames are widely used as lateral-load resisting systems in seismic design. The braces as the most important lateral-load resisting member in braced frame are typically connected to beams and columns by gusset plate connections. So the appropriate performance of braced frame systems also largely depends on the performance of gusset plate connections. Up to now, most research has focused on the tensile behavior of gusset plate connections, but the compressive behavior of gusset plate connections has received relatively limited attention.To extend the understand of the compressive behavior of gusset plate connections and develop a design method, parametric study of the compressive behavior of gusset plate connections which connect braces to beams and columns is conducted by use of the finite element computer program ABAQUS. According to whether considering the rotation stiffness supplied by the brace end or not, the analytical models are divided into two types: the first one are the gusset plate connections used in the structure located in low-seismic areas whose braces don't buckle or yield, and there are finite rotational restraints provided by braces at the end of gusset plate connections, the other one are the gusset plate connections used in the structure located in high-seismic areas, and there is no rotational restraint at the end of gusset plate connections for the failure of braces. The study parameters in this research include the thickness of gusset plate (tg), the ratio of the distance between the end of brace and the edge of gusset plate along the brace axis to the Whitmore width (L/ bE), the width used for splice members beside braces (w) and the brace angle (β). The analytical models are designed based on Code for design of steel structures (GB50017-2003). The elastic-plastic buckling analyses are conducted on the two types of models to get the ultimate load of gusset plate connections and to summarize the influence of parameters on the compressive behavior of gusset plate connections. A design method is proposed based on the above-mentioned analyses. Considering accumulated plasticity in gusset plate connections during seismic cycle load which can deteriorate the compressive behavior of gusset plate connections, further analyses are conducted on the models which will develop sufficient plastic after buckling and yielding. These analyses are performed under different load amplitudes and number of cycles to simulate the response of gusset plate connections under seismic load. Stability capacity deterioration factor (θ) is proposed as an index of the degradation of the compressive behavior of gusset plate connections, finally, a value of stability capacity deterioration factor (θ) is recommended to consider the cumulative degradation effect of plasticity in the design process.