| Huge casualties and property loss were caused by the WenChuan Earthquake occurred on May 12,2008. Meanwhile, all kinds of buildings and engineering facilities built at different periods were tested by earthquake in seismic zones, and they showed different damaging phenomenon. On the whole, seismic damage of fortified buildings is obviously lighter that of unfortified buildings. For the buildings at various times, seismic damage of the later ones is obviously lighter that of earlier ones. Especially the buildings designed and built after 1990, most of them were damaged moderately or even severely in the region where the intensity was one degree higher then designed intensity, but none of them collapsed. So the"three earthquake performance objectives"named"no failure for minor earthquake","repairable for moderate earthquake"and"no collapse for major earthquake"has been achieved. Each large earthquake brought the state and people with vast disasters, and also leave us plenty of damage lessons. Earthquake experts used these lessons to improve code for seismic design of buildings continuously, and make the code perfect. After WenChuan earthquake, GB50011-2001 was modified on the whole. In 2009,'"code for seismic design of buildings'exposure draft"GB50011-20XX was published.Richter magnitude 8.8 huge earthquake occurred in Concepcion the second city of Chile On February 27, 2010. The energy released of Chile earthquake is far more than that in Wenchuan, but the death toll is only 795 and 90% died of tsunami. One aspect is that the population was thin in the epicenter of Chile, another one is that Chile has strict seismic code and the quality of buildings is high.With China's entry into the WTO, international cooperation increased gradually. Our country's code for seismic design of buildings also began to integrate with international standards. So we should know the current situation and developing direction of foreign codes. This paper mainly introduced the evolvement of some provisions in our country's seismic codes, and chose some items in UBC97, IBC2006, FEMA450, EN1998-1 and NCh433 to contrast with those in GB50011-2001. By comparing and analyzing, I hope to provide help for the related personnel who want to know the development of Chinese seismic codes and the current conditions in Euramerican codes. The main works of this paper as follows:1,In the seismic fortification objective and level of buildings and the requirement of structural regularity, the paper respectively offered the development in our country's seismic codes and the difference with Euramerican and Chilean codes.2,The designed response spectra and the computing methods of seismic action in Chinese seismic code from the draft in 1959 to GB50011-2001, FEMA450 and EC8 were offered, and the adjustment reasons of those in Chinese seismic code had been explained. The designed spectrm of Chile was also introduced. And then, the value of seismic action in GB50011-2001, FEMA450 and EC8 were compared by an example.3,For multi-story masonry buildings, the limit values of total height and number of stories, the details of staircase and the installment of ring-beams and tie-columns were introduced in the evolvement of Chinese seismic code. And then, the seismic fortification basis, the seismic design details and the geometric requirements of walls were contrasted between Chinese and Euramerican codes.4,For multi-story and tall reinforcement concrete buildings, design details for frame structure, seismic-wall structures and frame-wall structures were presented in Chinese seismic code of each period. Later the difference in design details of frame beams, frame columns and seismic-walls were compared between Chinese and Euramerican codes. |
