Displacement-Based Fragility Functions for Low- and Mid-rise Ordinary Concrete Buildings

Abstract

Fragility functions are determined for low- and mid-rise ordinary concrete buildings, which constitute the most vulnerable construction type in Turkey as well as several other countries prone to earthquakes. A hybrid approach is employed where building capacities are obtained from field data and their dynamic responses are calculated by response history analyses. Field data consists of 32 sample buildings representing the general characteristics of two- to five-story substandard reinforced concrete buildings in Turkey. Lateral stiffness, strength, and deformation capacities of the sample buildings are determined by pushover analyses conducted in two principal directions. Uncertainties in lateral stiffness, strength, and damage limit states are expressed by using statistical distributions. The inelastic dynamic structural characteristics of the buildings investigated are represented by a family of equivalent single-degree-of-freedom systems and their seismic deformation demands are calculated under 82 ground-motion records. Peak ground velocity (PGV) is selected as the measure of seismic intensity since maximum inelastic displacements are better correlated with PGV than peak ground acceleration (PGA). Fragility functions are derived separately for different number of stories, which is a prominent parameter influencing the vulnerability of existing substandard concrete buildings.

Extending displacement-based earthquake loss assessment (DBELA) for the computation of fragility curves

“…Vacareanu, 2004, Akkar et al, 2005, Rossetto and Elnashai, 2005, Erberik, 2008. The methodology that is being proposed herein differs from the aforementioned ones because the method to calculate the nonlinear response of the buildings is simplified and does not suffer from the convergence problems often experienced when using the capacity spectrum method with real accelerograms (e.g.…”

“…As discussed by Rossetto and Elnashai (2005), there is not a unique methodology for the development of fragility functions and therefore, each approach will have its limitations and advantages. Several methodologies (Singhal and Kiremidjian, 1996;Dumova-Jovanoska, 2000;Akkar et al, 2005;Erberik, 2008; amongst others) have been proposed with different levels of simplification and efficiency in the past years. However, it is well established that one of the main drawbacks of any analytical methodology is the required computational effort.…”

The Global Earthquake Model Physical Vulnerability Database

“…For example, despite the fact that both Akkar et al (2005) and Bonnet (2003) developed curves expressing the probability of reaching or exceeding three damage states, the former study addresses these results as fragility curves, whereas the latter adopts the term vulnerability curves. This section provides a brief description of what is meant by each of the items currently being supported by the database.…”

Potential impacts from tephra fall to electric power systems: a review and mitigation strategies

“…While fragility functions have been used sparingly in probabilistic volcanic risk analysis, their usefulness has been demonstrated in other disciplines, notably in earthquake engineering to determine the probability of building failure at different ground shaking intensities (e.g. Rossetto and Elnashai 2003;Akkar et al 2005;Porter et al 2007). …”