Calculation of crack width of steel-concrete composite beams prestressed with internal tendon

摘要

Steel-concrete composite beam prestressed with internal tendon (SCCPIT) is composed of prestressed concrete slab, steel beam and shear connectors, etc. At present, there is no calculation formula for crack width of SCCPIT in current design codes Eurocode 4, ASSHTO or Chinese Code for Design of Steel Structures(GB 50017-2003). In this paper, the calculating formulas for crack width provided in Code for Design of Steel-Concrete Composite Structure (DL/T 5085-1999) were adopted as a basis for modification. On the basis of available test results, the calculation formulas for uneven coefficient of reinforcement strain and average crack space were modified by consideration of concrete slab width and combined force ratio. Hence, empirical calculating formulas of crack width of SCCPIT under negative moment were proposed. In order to verify the accuracy of the proposed formulas, five simply supported SCCPITs previously conducted by research group were analyzed, and comparisons indicated that the calculated values are in good agreement with the test results.