Dynamic Response Analysis Method of a High-Strength RC Beam Subjected to Long-Duration Blast Loading

An analysis method of normalized pressure–impulse (P-I) diagrams related to the ductility ratio of structural components is proposed, to quickly estimate the dynamic response of high-strength reinforcement concrete (RC) beams subjected to long-duration blast loading. Firstly, the overall bending deformation mode of RC beams is uncovered via explosion tests in a closed chamber, where the durations of the near-planar blast loadings are varied within 80–105 ms. Then, a single-degree-of-freedom (SDOF) model is established based on the bending deformation mode. The resistance function for the uniform pressure loading is developed using a novel approach, consisting of (1) developing and benchmarking a three-dimensional (3D) improved steel–concrete separated finite-element (FE) model; (2) using the benchmarked FE model to conduct numerical simulations for uniform pressure loading; and (3) idealizing the resistance function for uniform pressure using a bilinear relationship. Finally, the SDOF model is used to conduct parametric analyses and develop a normalized P-I diagram that can be used to analyze or design RC beams for far-field blast effects. This P-I diagram is verified using results from blast load tests that are primarily in the dynamic region. A total of 188 additional 3D nonlinear FE analyses of RC beams are conducted to expand the database in the impulse and quasi-static regions. Considering the limitations of the proposed method in predicting the shear-dominated deformation and the fracture behavior of members, the P-I diagram is applicable to the dynamic response of the bending deformation of members under far-field explosion, which can provide an important reference for the blast-resistant design and analysis of high-strength RC beams.

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