| The theory of regional confined concrete(RCC) is the inheritance and development of the theory of confined concrete. Compared with the normal confined concrete(NCC) columns, confined area of reginal confined concrete columns is transfered from the section center to the edge of the section because of the unique confined mechanism, it is advantageous to the situations such as ccentric force and seismic action which the maximum stress distributes the edge of column section. Early research has shown that reinforced regional confined concrete(RRCC) columns have a good seismic performance under high axial compression ratio(about1.2).With the rapid development of high-rise and super high-rise buildings, huge axial force will be appeared at the columns of the the lower floors of high-rise building. If utilize reinforced concrete structure according to the current specifications, column cross section will become so large and “short columns” will be formed. Reinforced regional confined concrete columns also can’t save column cross section effectively at high axial compression ratio(about1.2) under a very heavy axial load, this will lead to huge waste of building materials and building space.In order to avoid “short column”, channel steel regional confined concrete(CRCC) column is proposed on the basis of RRCC column in this paper, and change the stirrups for steel plate stirrups accordingly, so that higher confined efficiency can be obtained in CRCC column. Experimental researches about 5 CRCC columns’ seismic performance have conducted and finite element analysis has finished in this paper.Experimental researches have shown that considerable seismic performance and unique crack propagation are possessed simultaneously by CRCC columns. Compared with the RRCC column, the crushed concrete is encircled tightly by flange and web of channel steel in CRCC column, and the crushed concrete can continue to play a role, in addition, “hollow” will not form in closely damaged CRCC column as well. Compared with the steel reinforced concrete(SRC) column, crushed concrete within the confined area almost doesn’t fall off from the specimen and it can continue support ambient channel steel in CRCC column, so that the channel steel will not buckling quickly. SRC column’s damaged phenomenon such as after the stirrup failure, core concrete located in the outside of steel’s flange out of work soon and flange subsequently buckle by compression will not appeared in CRCC column. Considering the seismic performance indicators synthetically, all 5 specimens have better seismic performance and conspicuous performance is played with the increase of axial load in CRCC columns.The finite element analysis has shown that applying constitutive relation of RCC to simulate CRCC columns in finite element models is applicative. After analyzing the dilatancy angle, viscosity coefficient and damage factor’s influence rules to CRCC-3’s hysteretic curve, the corresponding parameters of the finite element models are recommended, and verification analysis have conducted on surplus specimens except CRCC-3, results have shown that experimental results agree well with the model results. |
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