Collapse mechanism and strengthening methods of cylindrical ILTDBS reticulated mega-structures

To investigate the progressive collapse resistance of intersected latticed threedimensional beam system(ILTDBS) reticulated mega-structures, a comprehensive numerical simulation study was conducted. The dynamic responses and collapse mechanisms of the ILTDBS reticulated mega-structure under various impact loading scenarios were systematically examined. The finite element modeling approach was first validated by reproducing a previously reported drop-weight impact test and comparing the numerical predictions with the experimental data. Subsequently, a refined finite element model incorporating cumulative member damage was developed in LS-DYNA using an explicit time-integration scheme. The model was employed to investigate the structural failure modes, collapse mechanisms, and transfer and dissipation of impact energy. On this basis, several impact-resistant strengthening strategies were proposed. The results indicate that the presence of the substructure provides substantial support to the main truss, thereby significantly enhancing the deformation capacity and impact resistance of the overall structure. Three primary failure modes were identified: slight structural damage, plastic spreading of the truss, and overall collapse. In the first two modes, redistribution of internal forces was observed, whereas overall collapse was characterized by the formation of plastic hinges at the ends of the truss beams. A critical relationship was found between the structural failure mode and the energy absorbed by the trussed arch. The absorbed energy was positively correlated with both the impact mass and impact velocity. Overall structural collapse can be effectively controlled through impact-resistant strengthening measures, including conceptual design optimization, reinforcement of critical members, and local addition of braces to restrain vulnerable regions. Recommended correlation coefficients are also provided to guide practical design.