| Taking full advantage of the charateristics of the two different materials-steel (tensile) and concrete (compressive), normal steel-concrete composite beams (NC-CBs, C50 and below) possess of many advantages, such as lighter deadweight, economic characteristics, convenient construction, etc, which makes it get more and more applications in engineering practice. Though NC-CBs possess of obvious advantages mentioned above, there are still many deficiencies existed, like low tensile strength, easy crack, deteriorative connecting performance under long-term load. In views of such characteristics as high strength, high ductility, high duration, low porosity and environment-friendly, Reactive Powder Concrete (RPC) will be introduced into the field of composite beams in this paper from the aspect of enhancing material behavior. Combined with steel girder, the super high mechanical performance and excellent duration of RPC can be taken advantage of to improve further the stress behavior of composite beams, consequently steel-RPC composite beams (RPC-CBs) formed.Following the way of comparative analysis, firstly a non-linear analysis of NC-CBs through ANSYS is carried out in this paper, and then compared with current results and test data of existing reference; it presents high concordance, which proves the feasibility of finite element calculating method. Secondly, based on the verified finite element model, the concrete slab is replaced to RPC slab with other parameters not changed, and then non-linear analyses of RPC-CBs through ANSYS are conducted. At the same time, parametric analysis is also conducted, including the thickness of RPC slab, yield strength and sectional dimension of steel beam. On the basis of the calculating results, this paper also studies the curvature ductility, displacement ductility and rotative ductility of the RPC-CBs. Finally, suggestions about steel-RPC connector design are given in this paper.After comparative analyses of NC-CBs, it is found that the bearing capacity of the RPC-CBs is obviously higher than that of the NC-CBs. Because of the higher compressive of RPC, it is difficult to reach the ultimate compressive strain even when excessively large plastic deformation occurred. Therefore, it is recommended that the ultimate tensile strain of the lower flange of steel beam (assumed to be 0.01 in this paper) should be taken as the sign of limit status of bearing capacity. The lower fibre of the RPC slab will not crack under regular service conditions; Besides this, because of the RPC's higher modulus, the section stiffness of RPC-CBs is much higher than that of the NC-CBs at the same size; Provided with the same stress performance, the slab thickness of RPC-CBs can be reduced upwards of 15% compared with that of the NC-CBs, accordingly the span can achieve a further increase; After parametric analyses, it is found that both of upgrading the steel beam strength grade and expanding the lower flange dimension can effectively enhance the limit bearing capacity of RPC-CBs, and make it's compressive stress upgrade to a higher level; If harden stage of the steel beam permitted, the real ductility of RPC-CBs is much more than that of the NC-CBs; Additionally, restricted by the studs space, the RPC-CBs possibly could not reach completed connection.If RPC could be applied to composite structure, it will further lighten the deadweight of the slab, increase the span, reduce the late maintenance cost, improve economic efficiency and extend the application domain of new materials in engineering, and therefore has a good future.
|
PDF Full Text Request