Comparision Research Of Determining The Peak Acceleration Velocity In Seismic Design

With the development of economy and technology, how to effectively reduce seismic hazard has raised lots of concerns. The rational selection of seismic fortification parameter is vital to the calculation of seismic effects in structural engineering design. The transition from seismic intensity zoning to ground motion parameters zoning in "Seismic ground motion parameters zonation map of China"(GB18306-2001) has led many researchers to do a lot of work on how to determine parameters of ground motion, including converting experience factors of ground motion parameters in certain probability, converting I type extreme value of seismic intensity, the relation between seismic intensity and ground motion parameters and so on. Though zone map gradually reduces the effect of seismic intensity and define ground motion parameters including ground motion acceleration velocity, no direct converting method of ground motion in different probability level has been accepted and applied in design by codes and engineers.This paper presents the background of current seismic technique research through introducing seismic theory, the development of seismic codes and comparison between Chinese and US codes. And it uses Ⅱ type extreme value distribution to represent the relation between peak acceleration velocity and exceeding probability, gets converting formula of peak acceleration velocity between different probability levels, and compares converted results with the values in the new edition of "Seismic ground motion parameters zonation map of China"(Exposure draft2012) and "Code for seismic design of buildings"(GB50011-2010). Furthermore, comparison is made among converted result of ground motion acceleration velocity, value in current earthquake resistant design code, value in Wuhan urban small zoning ground motion parameters and value in safety assessment report. Applying these four ground motion acceleration velocities to the structure response spectrum analysis of constructional projects in Wuhan and comparing structure floor stiffness, floor displacement and interlayer displacement angel in different levels of lateral seismic effect.The main conclusions of this paper are summarized as follows:1The new edition zonation map regulate values of ground motion acceleration velocity in different probability level. It suggested the values are5%～24%less than values in current earthquake resistant design code, except when under rare seismic effect in high intensity zone. If under rare seismic effect in high intensity zone, the values are11%-22%more than values in current earthquake resistant design code. It shows that new edition zonation map has higher requirements for robustness of structures under rare seismic effect in high intensity zone. But this change has little influence on Wuhan. We also can see from the comparison that the proposed converting method in this paper gets a similar result to suggested value of new edition zonation map.2Applying converted result of ground motion acceleration velocity, value in current earthquake resistant design code, value in Wuhan urban small zoning ground motion parameters and value in safety assessment report to the structure response spectrum analysis of constructional projects in Wuhan, it is found that the seismic effect of long period structure is obviously less in Wuhan small zoning response spectrum analysis than the calculation result in earthquake resistant code response spectrum. At the same time, for Wuhan City it is smaller to calculate seismic effect by earthquake resistant code acceleration velocity than by Wuhan small zoning and safety assessment report acceleration velocity. Moreover, the ground motion acceleration velocity converted by II type extreme value distribution is close to the safety assessment report result and the difference in seismic response results is less than15%.This paper uses II type to characterize the distribution of ground motion acceleration velocity in different probability level, gets a lot of discoveries in the process of comparative study. The paper also analyses the actual cases in order to combine theory closely with practice. All of these will be valuable for the future seismic design.