Abstract: In the evaluation of anti-explosion performance for significant building and protective engineering structures,a direct simulation using appropriate computational technique is very necessary,wherein the simulation precision of blast loads becomes mainly concerned problem.This paper presents a numerical simulation study on the prediction of the blast load in free air using AUTODYN software,with focus on the sensitivity of the simulated blast load to the mesh grid size and solution algorithms.The results are compared with empirical predictions and blast parameters from TM5-1300.It is found that the mesh size has a remarkable effect on peak overpressure and a certain extent effect on impulse,and the Euler-FCT algorithm in contrast with Euler-G improves the accuracy and efficiency.However,the blast loads tends to be systematically underestimated;the underestimation of blast load may be compensated by imposing a charge adjustment factor of 1.5.The dynamic response of the reinforced concrete slab under nearby explosion is then analyzed using a coupled scheme,and the full processes of the deformation and damage of RC slab such as the cracking and break-up of concrete,yield of reinforcing bars,and local perforation are observed realistically.