Study On The Effects Of Axial Compression Ratio On Seismic Capacity Of Prestressed Concrete Frame

The span of prestressed concrete frame is usually quite large comparing with therelative small amount of the columns. If the prestressed concrete frame is designed by thelimit of column axial compression ratio in common reinforced concrete rules, the way willcause that the column section size is too small so as to the severe damage underearthquake, the structure will form the interlayer yielding mechanism. In the other hand,excess emphasis on the limit of column axial compression ratio will leads to the cost up.This paper carries out research on the efforts of axial compression ratio on the prestressedconcrete frame seismic capacity and discusses the rationality and economy of the limitedvalues of axial compression ratio in prestressed concrete frame.First this paper discusses the characteristic of prestressed concrete frame, thedevelopment course and research status about seismic problem of the structure；Theeffects of axial compression ratio on the seismic behavior of common concrete columnsand frames are summarized. Second, according to the correlated rules, six singleprestressed concrete frames in religion of8degree (0.20g) are designed, in which there arethree layers and two spans. The axial compression ratio in columns is controlled bychanging the section area of columns. The Reinforced parameters of six single prestressedconcrete frames with different axial compression ratio are obtained in the condition of nomanual intervention and pushover analysises of the prestressed concrete frame models arecarried out respectively. the analysis results show that the ductility of prestressed concreteframe is improved with the decrease of axial compression ratio；In order to makeprestressed concrete frames appear mixed yielding mechanism under rare earthquake andreduce the economic loss because of the strengthening and repair after earthquake, it issuggested that the axial compression ratio of interior column should be controlled under0.4and the axial compression ratio of side column should be controlled under0.2.At the same time, considering that axial compression ratio is a comprehensive index，the effects of the column reinforcement area on the seismic capacity of prestressed concrete frame by changing column reinforcement magnification factor under the sameaxial compression ratio are investigated for comparing with the effects of different axialcompression ratios. the analysis results show that the increase of bottom columnreinforcement magnification factor improves the mechanical behavior of the structure butcan not change the yielding mechanism fundamentally；Comparatively speaking, axialcompression ratio is an important factor that affects the seismic capacity of prestressedconcrete frame; because of the interior column is usually in the condition of smalleccentric compression, the contribution of structure seismic capacity by increasing thecolumn reinforcement area only is limited.