Experimental and numerical investigation of incident angle effects on the dynamic response of RC beams under near-field blast loading

Reinforced concrete (RC) beams face potential near-field blast threats as key structural components in building structures. To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast loading, this paper presents both blast tests and numerical simulation studies on RC beams. First, near-field blast tests were conducted on five RC beam specimens under strong and weak-axis bending loading. Then, a refined finite element model of RC beams was established to verify the applicability of the adopted finite element analysis method. Finally, based on the calibrated finite element model, the failure mechanisms of RC beams were explored, and the influence of blast incidence angle on the failure modes and dynamic responses of RC beams was investigated. The results indicate: (i) Near-field blast loading demonstrates pronounced non-uniform distribution patterns. Under strong-axis incidence, clearing effects beyond the mid-span region are more significant than weak-axis incidence, leading to accelerated impulse attenuation. (ii) Three consecutive developmental stages primarily control the damage mechanism of RC beams: stress wave-induced local damage, local deformation causing plastic hinge propagation, and free vibration of the beam; (iii) As the scaled distance decreases, the failure mode of RC beams under weak-axis blast loading evolves from flexural failure to local failure. The resistance mechanism of RC beams under weak-axis blast loading is more prone to transition from compressive membrane action to tensile membrane action, reducing their blast resistance capacity; (iv) As the explosion incident angle θ increases from 0° to 90°, the blast wave-structure interaction transitions from regular reflection to Mach reflection and back to normal reflection, causing the dynamic response of RC beams to first decrease then increase, with corner concrete spalling damage being the primary failure mode. • Near-field blast testing of five RC beams along the strong and weak bending axes was conducted. • The damage mechanisms of RC beam were analyzed subjected to near-field blast loading along the strong and weak bending axes. • The effect of incident angle on the damage patterns and dynamic response of RC beams was investigated.