Approximate seismic risk assessment of building structures with explicit consideration of uncertainties

Abstract

SUMMARYAn approximate seismic risk assessment procedure for building structures, which involves pushover analysis that is performed utilizing a deterministic structural model and uncertainty analysis at the level of the equivalent SDOF model, is introduced. Such an approach is computationally significantly less demanding in comparison with procedures based on uncertainty analysis at the level of the entire structure, but still allows for explicit consideration of the effect of record-to-record variability and modelling uncertainties. A new feature of the proposed pushover-based method is the so-called probabilistic SDOF model. Herein, the proposed methodology is illustrated only for reinforced concrete (RC) frames, although it could be implemented in the case of any building structure, provided that an appropriate probabilistic SDOF model is available. An extensive parametric analysis has been performed within the scope of this study in order to develop a probabilistic SDOF model, which could be used for the seismic risk assessment of both code-conforming and old, that is, non code-conforming RC frames. Based on the results of risk analysis for the four selected examples, it is shown that the proposed procedure can provide conservative estimates of seismic risk with reasonable accuracy, in spite of the employed simplifications and the relatively small number of Monte Carlo simulations with Latin hypercube sampling, which are performed at the level of the SDOF model. An indication of the possible default values of dispersion measures for limit-state intensities in the case of low to medium-height RC frames is also presented.

Analysis in seismic provisions for buildings: past, present and future

“…Extensive studies have been performed in order to determine typical dispersions b NC of the capacity at failure for reinforced concrete (RC) building structures using S a (T) as the intensity measure (Kosič et al 2014(Kosič et al , 2016. The results of these studies showed that the values depend on the structural system and on the period of the structure T. However, in a simplified approach, it may be reasonable to assume b NC ¼ 0:5 as an appropriate estimate for RC building structures, with the exception of very stiff structures, where b NC is smaller.…”

Analysis in Seismic Provisions for Buildings: Past, Present and Future

“…Extensive studies have been performed in order to determine typical dispersions β NC of the capacity at failure for reinforced concrete (RC) building structures using S a (T) as the intensity measure (Kosič et al 2014(Kosič et al , 2016. The results of these studies showed that the values depend on the structural system and on the period of the structure T. However, in a simplified approach, it may be reasonable to assume β NC ¼ 0.5 as an appropriate estimate for RC building structures, with the exception of very stiff structures, where β NC is smaller.…”

Simplified Assessment of Expected Seismic Losses for as Built and Retrofitted Rc Buildings

“…Figure 10 shows the collapse fragility curves obtained from NLRH analyses and with SPO based approach. The latter curve is built considering PGAc,PO as median capacity and the logarithmic dispersion =0.5, as indicated in [33] for mid-rise old RC frame buildings. It can be noted that the fragility curve representation obtained starting from SPO analyses allows a fair approximation of NLRH-based curve.…”

“…In fact, as depicted in Figure 13, the median capacity for wrap1 increases from the original value of PGAc,PO =0.58g to PGAc,PO,wrap1=0.72g while for the wrap12 and wall configuration it increases up to PGAc,PO,wrap12=1.06g and PGAc,PO,wall=0.81g. Note that for the retrofit wall that adopts shear wall a logarithmic dispersion =0.63, as indicated in [33] for mid-rise coupled wall-frame buildings is adopted. Total repair costs are calculated for three building configurations and different earthquake intensities adopting the SPO approach and the procedure outlined in 2.2.…”