Evaluation of sewer network resilience index under the perspective of ground collapse prevention

Generally, when evaluating the resilience of infrastructure, the four properties of resilience robustness, rapidity, resources, and redundancy (4Rs) are widely considered. However, there is little research on the resilience assessment of sewer networks. Therefore, to establish a framework to evaluate sewer network resilience under the perspective of urban ground collapse prevention, this study considers the 13 second-level detailed indicators corresponding to the 4 first-level indicators (4Rs) based on literature reviews and experts' opinions. An analytic hierarchy process (AHP) is used to obtain relative weights of each indicator and a weighted sum method (WSM) is used to evaluate sewer network resilience index (SRI). The evaluation system was applied to 8 small blocks of selected drainage areas in Seoul, South Korea, and the SRI of 8 small blocks are computed. This study could help the sewer management department to make decisions and manage sewer network assets that enhance the resilience of the sewer networks.

Pengaruh Penerapan SNI 1726:2019 Terhadap Desain Struktur Rangka Momen Beton Bertulang Di Indonesia

Telah diterbitkan peraturan gempa yang terbaru, yaitu tata cara perencanaan ketahanan gempa untuk struktur gedung dan non gedung SNI 1726:2019 menggantikan peraturan gempa sebelumnya, SNI 1726:2012. Dalam penelitian ini spektra desain yang ada dalam SNI 1726:2019 dibandingkan dengan spektra desain dalam SNI 1726:2012 dengan mengambil sampling 21 kota besar yang dianggap mewakili seluruh wilayah Indonesia. Dari hasil perbandingan tampak sebagian besar mengalami kenaikan walaupun tidak sedikit yang mengalami penurunan dan ada pula yang tetap. Penerapan faktor amplifikasi Fa menurut SNI 1726:2019 menyebabkan adanya fenomena anomali di daerah-daerah rawan gempa, dimana nilai spektra desain untuk perioda pendek di situs Tanah Lunak (SE) dapat lebih rendah daripada nilai untuk Tanah Sedang (SD) dan Tanah Keras (SC). Fenomena anomali tersebut terjadi di kota-kota dengan SS di atas 0,75 g. Penelitian dilanjutkan dengan melakukan studi komparasi dengan membandingkan besaran gaya gempa yang dihitung menggunakan SNI 1726:2012 dan SNI 1726:2019 terhadap suatu sampel model struktur gedung yang diasumsikan terletak di Jakarta pada kondisi tanah lunak (SE). Terjadi kenaikan base shear desain pada gedung yang dihitung menggunakan SNI 1726:2019 dibandingkan gedung yang dihitung menggunakan SNI 1726:2012 sebesar 128,93% untuk arah x dan 131,23% untuk arah y. Sampel model struktur gedung memiliki level kinerja life safety jika dievaluasi terhadap peraturan gempa SNI 1726:2012 dan mengalami penurunan kinerja dari level life safety ke collapse prevention jika dievaluasi terhadap gempa peraturan baru, SNI 1726:2019.

Evaluation of Seismic Fragility Analysis of the Mega Sub-Controlled Structural System (MSCSS)

The improved mega sub-controlled structure system (MSCSS) significantly reduced the building responses and improved the control effectiveness as compared to conventional mega substructure (MSS). However, since the MSCSS is designed to resist future earthquakes, the seismic risk assessment of the structure remains a significant concern. In this study, the seismic risk analysis of MSCSS is performed to probabilistically compare the building performance and its resistance to future earthquake damage at certain categories of limit states (LSs), which include category one (slight damage, moderate damage, and collapse damage LS) and category two (damage control and collapse prevention). The comparison is realized with the result of the traditional MSS. The probability of exceedance of the above damage LS for a particular ground motion (GM) intensity (i.e. Sa (T1,5%)) is evaluated to assess and compare the vulnerability of these buildings. The evaluation is done through developing fragility curves and relationships for MSCSS and MSS. The result showed that the improved MSCSS has strong seismic resistance ability and provides a better response from a nonlinear analysis result. Furthermore, the fragility curve of moderate and collapse damage LSs indicated that MSCSS requires higher GM intensity to reach a moderate and collapse damage LS than MSS. That means MSCSS is the most stable with a significant difference as compared to its counterpart. This is also true for the second category of LS, that is, damage control and collapse prevention. While at the slight damage LS, both the MSCSS and MSS require approximately the same GM intensity to reach a slight damage LS, as the difference is not significant.