Researches On Design Theory Of RC Special-Shaped Columns

In this paper, the following work has been done:1 The load-bearing capacity of L, T and +-shaped columns under axial compression and biaxial bending is calculated by a numerical integral program. The non-dimensional relationship of load-bearing capacity is put forward, the virtue of which is that, given the same ratio of limb length to thickness, one curve presents many kinds of section dimensions and concrete strengths, thus the quantity of present relation curves is greatly reduced. Based on this, a program for computation of longitudinal steels is given.2 The effects of load angle on load-bearing capacity of L, T and +-shaped columns under axial compression and biaxial bending are discussed. As for L and T-shaped columns, load angle has a great effect on bending capacity of them, mainly because of the asymmetry of sections. But for +-shaped columns, the effect of load angle on load-baring capacity is not much significant.3 Analysis on axial compression ratio of L, T and +-shaped columns is undertaken. It indicates that for L and T-shaped columns, axial compression ration is very low when web is in compression, but for +-shaped columns, axial compression ratio approaches to that of rectangular columns. And the axial compression ratio index of L, T-shaped columns considering section dimensions is given.4 Experimental researches on L-shaped columns are conducted, the results agree well with theoretical ones. It approves that for L-shaped columns, the ductility is truly bad when web is in compression. Though axial compression ratio takes 0.536, bad ductility results.5 Results of an experimental investigation on shear behavior of L, T and +-shaped columns are presented. The effects of shear-span ratio, axial compression ratio, stirrup contents and loading direction on shear behaviors of L, T, and +-shaped columns are discussed. Combining with test data of others, the formulas for shear strength of L and +-shaped columns are given. The expressions for T-shaped columns given in Design Code for Concrete Structures are verified. Compared with test results, good agreement is achieved.6 Experimental researches on two-directional shear behavior of L, T and +-shapedcolumns are undertaken. For L, T and +-shaped columns, the shear bearing capacity and ductility under two-directions is not worse than that under frame direction. Therefore, for L, T and +-shaped columns, as long as the shear bearing capacity and ductility in frame-direction satisfy requirements, the shear bearing capacity and ductility under two-directions need not to be checked.