Development Of Fragility Curves For Medium Rise Reinforced Concrete Shear Wall Residential Buildings In Puerto Rico.

Abstract

Puerto Rico is situated in an earthquake prone region. Because of the imminent risk of
being affected by a strong earthquake, it is important to study the damage vulnerability of existing
structures in the Island. This study is directed to medium rise concrete residential buildings in Puerto
Rico. Most of multistory residential buildings in Puerto Rico are reinforced concrete structures with
lateral resisting system composed by shear walls oriented in both directions. The lack of local
earthquake vulnerability curves for Puerto Rico and the fact that local construction practice differs
from that in USA motivates the author to look at the development of reliable fragilities curves based on
typical buildings properties and selection of ground motions based on local geology characteristics and
past worldwide earthquakes scaled to different peak ground acceleration to obtain a wide range of
maximum accelerations. The analytical models are two-dimensional and are analyzed using the
nonlinear dynamic time history method considering both flexural and shear nonlinear behavior for
shear walls. Algan’s formulation (1982) and HAZUS drift limits were used to calculate the expected
damage of the models. Damage of the structures is quantified based on the inter-story drift ratio of the
structure. The damage states considered were: Minor, Moderate, Substantial and Major, for Algan and
Slight, Moderate, Extensive and Complete for Hazus. With this information, lognormal functions
expressed in the form of two parameters (log-median and log-standard deviation) were fitted and
fragility curves developed as a function of PGA. A set of four fragility curves, one for each damage
state is developed for each scenario studied. These curves are useful tools for the insurance companies
in Puerto Rico in order to improve their risk assessments.