The Analysis On The Rationality Of Seismic Fortification Measures For Concrete Structures In China

Earthquake disaster is one of the most serious disasters, which may result in heavy casualties and economic losses. Seismic design is important Based on experimentations and analysis about seismic fortification measures in domestic and overseas, and by comparing seismic design provisions with seismic codes in New Zealand, European Community, the United States, it is analyzed the rationality of seismic fortification measures of concrete structure in China.To guarantee the stability of the frame in strong earthquake motion, and on the basis of analysis on the concept of"Capacity Design"in the above three countries seismic design provisions, it is advised that the moment amplification coefficients at the bottom sections of columns for the frame structures in some seismic intensity be increased to reduce the possibility of the frame column yielding. Taking the above three countries seismic codes as reference, it is recommended that it be added details of seismic design by using diagonal shear reinforcement to safeguard beams against sliding shear failure, When the Positive-Negative shear forces are reverse and the ratio is high. The ductility of the frame structures in high intensity regions in China is low. The main reason is that the length of potential plastic hinge regions in beams is short. It is advised that the length of potential plastic hinge regions for seismic grade 2 and 3 be increased. And it is recommend that it be added some details of seismic design in potential positive plastic regions for frame structures in intensity 9. The minimum reinforcement ratios of the frame beam and column of seismic grade 1 given in Chinese code is reasonable. But those of seismic grade 2, 3, 4 are low. It is recommended that those of seismic grade 2, 3 and 4 be enhanced. It is important for good ductility for concrete structures by restricting the axial compression ratios of columns, which may be increased by increased the ratios of hoops and by using continuous compound spiral reinforcement columns.