Towards improving the seismic hazard map and the response spectrum for the state of RN/Brazil

Abstract

Although Brazilian seismic activity is defined as low to moderate, it is known that intraplate earthquakes can also be associated to high intensities. In Brazil, the state of Rio Grande do Norte (RN) is one of the most seismically active areas, but there is no specific study to evaluate the seismic hazard in this region. This paper presents analyses towards improving the seismic hazard map, the peak ground acceleration value and the response spectrum of RN. The methodology is based on Probabilistic Seismic Hazard Analysis, comparing the results to the design criteria defined in the Brazilian code NBR 15421:2006 (Design of seismic resistant structures – Procedure). The analyses show that, in general, the code sets conservative values for the peak ground acceleration and for the design response spectrum; however, related to this last one, the shape is quite different.

Prospective study on risk-targeted seismic hazard maps for Northeastern Brazil: case study in Zone 1 of ABNT NBR 15421:2006

“…The hazard maps developed by [19] outline a zone with a high hazard among the states of PB and RN (Figure 4a). As noted by Pereira et al [29], this higher hazard zone appears to be inconsistent compared with the national catalogue or hazard assessments for the region (e.g., [4], [21]). In the following, this issue is briefly addressed.…”

“…The other two risk-targeted maps (Sa(T = 0.2s) and Sa(T = 1.0s)) can be used to develop a RS compatible with alternative methodologies, such as the one in ASCE 7-16 [26]. A possible change in the code [8] RS shape has begun to be discussed ( [21], Alves and Santos [38]); therefore, it seems convenient to contribute to this. Moreover [18], demonstrated that risk-targeting affects each spectral ordinate differently.…”

“…Nóbrega et al [21] briefly explored the impact of increasing the RP of design accelerations to 2475 years in the state of Rio Grande do Norte (Brazil). In general, accelerations increased about 2-4 times.…”

Seismic reliability assessment of a non-seismic reinforced concrete framed structure designed according to ABNT NBR 6118:2014

“…Hazard curves are derived through probabilistic seismic hazard analysis (PSHA) of a specific region or site [16]. While there are a few PSHA studies for Brazil ([2], [10], [11], Souza et al [18], Almeida et al [19], Borges et al [20], Alves [21], Nóbrega et al [22]), studies focusing on fragility functions are currently lacking, as can be observed in the database presented in Silva et al [23], although several were conducted worldwide (Ramamoorthy et al [24], Ellingwood et al [25], Ramamoorthy et al [26], Kappos and Panagopoulos [27], Rajeev and Tesfamariam [28], Jeon et al [29], Amirsaradi et al [30]).…”