Progressive collapse and soil stress analyses of Manupali steel truss bridge in Lantapan, Bukidnon under hydraulic and traffic threats

Bridges designed to comply with current design codes may not provide enough strength to arrest a possible local failure following an abnormal event, thus leading to a progressive collapse. One may employ different approaches that vary according to linearity and dynamicity to analyze the potential of a structure to progressive collapse. Together with a prior risk assessment, this study analyzed the susceptibility of the Manupali steel truss bridge to progressive collapse using an adapted nonlinear static approach and assessed the bridge’s pile foundation capacity concerning changes in the imposed stresses caused by the dynamic effects of progressive collapse. Using P-Delta analysis in STAAD.Pro CONNECT Edition V22, this study determined that under its self-weight, the Manupali steel truss bridge is susceptible to progressive collapse, i.e., it is fracture critical. Nonetheless, being such does not mean the bridge is inherently unsafe, only that it lacks redundancy in the design. Furthermore, this study found that a collapse does not significantly detrimentally affect the foundation system except when the dynamic effect is so tremendous. With the results, this study recommends that the design of bridges should consider abnormal load cases to mitigate progressive collapse.