Benefit of structural access panels (SAP) for post-earthquake structural health monitoring

Abstract

This paper develops a method to quantify the benefit of using structural access panels (SAPs) placed in internal partition walls (IPWs) or ceilings near the dissipative elements of structures for post-earthquake structural health monitoring (SHM) without damaging the building non-skeletal elements (NSEs). The benefit of SAPS is considered for different levels of shaking considering the possibility of (i) no likely structural damage, (ii) likely building irreparability, or (iii) building NSE damage. The methodology is developed for shaking intensity scenarios with annual shaking probabilities of exceedance ranging from 1/25 to 1/10,000. Structural demands for different scenarios are initially obtained using time history analysis. The number of scenarios was increased by additionally generated demands assuming lognormal distributions of response. Monte-Carlo analysis was used to assess the likelihood of reaching particular decision states, considering uncertainty associated with achieving these states. Probabilistic (time-based) benefits of using SAPs are also considered. Additionally, buildings with both conventional IPWs and low-damage IPWs are considered. Finally, the methodology is applied to a realistic 6 storey eccentrically braced frame (EBF) structure. In the study, the scenario-based analysis indicated that the SAPs were not effective during very small earthquake events where the post-earthquake inspection will not be triggered, or during very large events where the building is externally observed to be irreparable. Furthermore, if the NSEs equipped with SAPs sustain significant damage, SAPs were not needed for inspection. As a result, the SAPs were more beneficial when installed in low-damage NSEs, as compared to conventional NSEs, especially during moderate to high shaking levels. For the casestudy building considered, the probabilistic loss study indicates the break-even time for SAPs to be economical, considering initial installation costs, and inspection savings related to direct damage and downtime losses, was less than 2 years. The benefit-to-cost ratio of SAPs for rapid and reliable post-earthquake inspection was up to 26 over the expected building life of 50 years.