Seismic Vulnerability Evaluation of Pipe Rack Supporting Structures in A Petrochemical Complex

Abstract

Seismic evaluation of pipe rack supporting structures in a petrochemical complex as one of the most important parts of structural systems for safe and stable production processes have been studied in this paper. The behavior of these supporting structures is similar to steel or reinforced concrete frame supporters for elevated processes pipes. Qualitative and quantitative methods of seismic vulnerability evaluations have been used according to the ASCE-1998 standard. In qualitative evaluation, the seismic vulnerability factors are determined by visual inspection and walk down the structural systems. Computer modelings have been used in quantitative evaluation of the supporting structures, including equivalent static analysis and linear dynamic analysis by considering torsion and P-∆ effects. Site specific earthquake records and design spectrum have been used as input seismic forces. Also, gravity and thermal loads based on the existing documents and design calculation sheets and specification notes have been considered in analyses. Gravity and lateral load combinations have been considered for seismic evaluation of foundation systems. Overturning stability of structures and uplifting of foundation systems due to gravity and lateral loads, and also, lateral displacements, frame element and connection capacities, have been investigated. However, different methods of seismic strengthening and retrofitting of structural system have been proposed.