Preliminary Analysis Of P-△ Effect On Nonlinear Dynamic Response Of Seismic Frame

The present paper reviews the research of the second order effect on the structure. Based on this, this paper points out the essential difference between the static p-delta effect and the dynamic p-delta effect and that the static p-delta effect can't manifest the structure's dynamic feature and the nature of the dynamic load; Then it summarizes and comments on various countries' research on the influence of effect on the dynamic p-delta effect, and elaborates on the p-delta effect used in earthquake resistance standard adopted by various countries such as US, Canada, European Union, China and so on; Finally, it reviews the influence of the inelastic dynamic response on earthquake resistance frame through the inelastic mechanical analysis method and stability coefficients of the three groups are 0.042, 0.055, 0.07, respectively.Based on the research work stated above,there are found several preliminary understanding:①The dynamic analysis shows that the P—Δeffects of the dynamic response under the different power characteristics depend on dynamic loads,which may increase or reduce the structural response. It is different from the P—Δeffects of the static response,which is always increase the structural response.②The inelastic dynamic analysis results show that the influence about P—Δeffects on inelastic response of the structure exhibits higher dispersion with the different ground motion input, basically the influence about the P—Δeffects on inelastic response of three frames with first earthquake-resistance level is little, the stability factor are respectively 0.042, 0.055, 0.07; it is also found that the influence about the P—Δeffects on earthquake motion is significant.③The structures considered the P—Δeffects in section design enhance their relative yield level, augment the earthquake action and the corresponding floor shear when they subject to the same intensity level of ground motion. However, it is different between the increment coefficient of every floor shear and the distribution of internal force increment coefficient considered the P—Δeffects in section design.④At present, some nation or group of nations for instance, European Union, Canada, Mexico and so on, while there are some difference in aseismic structure when considering the effect on specific stipulations in their design codes or regulations, But the mentality is basic consistent, namely realizes the equal bearing capacity of structure under the given strong earthquake response displacement. This mentality is hysteresis the characteristic take the single degree-of-freedom system ideal double broken line to propose as the basis. In view of the recent already aware of the practical engineering exists overall overstrength features of all kinds of statically indeterminate structure, the idea above has become too conservative.