Crack Width Calculation Method of Fiber Reinforced Concrete Composite Bridge Deck

Abstract:

To consider the crack bridging effect of steel fibers in fiber reinforced concrete (FRC) and its beneficial effect of restricting crack initiation and development in composite bridge deck, a calculation method of residual stress and cracking width was proposed. The main parameters influencing the residual stress f_R,1 were yielding stress of fiber σ_y, fiber volume fraction V_f, compression strength of concrete f_cm, fiber length l_f, fiber aspect ratio a. The correlation between the afore mentioned parameters and the residual stress was derived. Based on the linear regression analysis from test results of 35 three-point bending tests on notched beam recorded in the literature, an equation to calculate f_R,1 with 95% confidence level was proposed. Including the contribution of residual stress in the calculation method for the composite structure under negative moment suggested by Eurocode 4, a crack width calculation method for FRC composite bridge deck was proposed. A FRC composite bridge deck specimen subjected to negative moment loading was used to validate the calculation method. The results show that the calculated rebar stress and crack width fits well with the tested value.

Key words:bridge engineering;crack width;residual strength;fiber reinforced concrete composite deck;negative bending region