Abstract: Significant computational cost can be saved by using a hybrid method combining Monte Carlo (MC) method with a response surface in stochastic simulation. However, when the applied load is close to the cracking load, it can be found that the real deflection response of a reinforced concrete (RC) beam may not be smooth. In this case, the traditional response surface method, which covers the all responses with a single function, may induce significant error. To avoid this problem, a piecewise response surface is adopted in an MC simulation model for RC beams. The deflection variability RC beam tests is evaluated using the presented model. The parameters of piecewise response surface are discussed. The results demonstrate the usefulness of the present model in computing the stochastic nonlinear deflection of cracking RC beam.