Vulnerability Assessment of Port Buildings

Abstract

Ports are lifeline systems that function as a storage and maintenance facilities for the transport of cargos and people via water. The port structures are frequently exposed to failure under severe seismic loading. It was not only observed during 1995 Kobe earthquake but also during 1989 Loma Prieta and 1999 Kocaeli earthquakes. The scenario is more critical if the port sites are located within the seismically vulnerable area like Gujarat state of India. During 2001 Bhuj earthquake, Kandla port building was damaged. In this report, a study has been carried out to find out the damage of port buildings. For this purpose Kandla port building has been selected as a typical building and the same is analyzed and designed as per Indian standards. The port building is modeled using 2D Applied Element Method (AEM) to perform damage analysis typical port building. In addition to this other methods have been used to calculate the response of port building including soil-structure-interaction (Annexure of Port Building). These analyses gave good insights of structural behavior but their response values are low and hence not considered in calculating the damage. Method used to estimate the damage is presented in the main part of this report. Pushover analysis is done to get base shear vs roof displacement of building using displacement control method. Using energy dissipation approach, damage is quantified at every displacement level and normalized to 1. It means when D=0 then building will not experience any damage and if D=1 means it is complete collapse. The damage states of the structure were defined as no damage (D<0.2), slight damage (D<0.4), Moderate damage (D<0.6), severe damage (D<0.8) and complete collapse (D>0.8). A fragility curve has been developed to quantify the damage of building with respect to different peak ground accelerations. Based on the fragility analysis of port building the following recommendations are drawn. It is found that the damage to the typical port building is 0.16 when it is subjected to a peak ground acceleration of 0.218g from seismological studies as expected at KHF Mandvi. If the same building is located at Jodiya which experiences 0.377g the damage would be o.25 and in case of building located at Jhangi which experiences a peak ground acceleration of 0.396g from Katch Mainland fault the building would experience a damage of around 0.34 damage.