Isolation design and numerical calculation of isolated rubber bearing in continuous beam bridge in high seismic intensity area

The stability of bridges in the face of earthquake hazards has always been the focus of construction engineering. At present, a large number of bridge construction has begun to use isolation rubber bearings to increase the seismic capacity of bridges. However, in the face of high-intensity earthquake disasters, the seismic performance of the bridge is gradually unable to meet, the main reason is the lack of relevant research on the seismic performance of the bridge in high seismic intensity area. Therefore, this study will explore the changes of the bridge in the face of high-strength earthquake, and try to use high damping rubber bearings for the isolation design of the bridge. By establishing the finite element model of continuous bridge combined with isolation rubber bearing, the numerical calculation of bridge element is carried out on this basis, and the isolation effect of isolation rubber bearing is analyzed. The results show that the compression resistance and shear resistance of the isolated rubber bearing are strong. Under the influence of different seismic waves, the maximum displacement of the bearing is 0.131 m and the maximum horizontal force is 389.6 kN, which are lower than the allowable value of the bridge, and the overall seismic performance of the bridge has been significantly improved, which can play a good theoretical support in the construction of continuous bridges in high seismic intensity areas.

Benefits of Defining Geological Sensitive Zones in the Mitigation of Disasters Along Earthquake Fault Zones in Taiwan – The Case of Milun Fault

In Taiwan, the main purpose of earthquake fault zone legislation is to prevent earthquake-related disasters around the surface traces of active faults, particularly in urban areas. Here, the Geologically Sensitive Area (GSA) of the Milun Fault (Milun Earthquake Fault Zone) is used as an example to reveal the importance of such legislation. Field data collected along the Milun Fault before and after the 2018 Hualien Earthquake were used to reveal the reappearance of damages within the GSA. The 2018 Hualien Earthquake represents one of the shortest recurrence intervals (67 years) among all major faults in Taiwan. Most of the surface ruptures and damaged buildings in Hualien City were within the Milun Fault GSA and concentrated on the hanging wall of the fault. Moreover, 61% (91/148) of the damaged buildings and 83% (692/835) of the surface ruptures occurred within 100 m of the fault line. The results of this study demonstrate the importance of defining GSAs of active faults for mitigating earthquake hazards.

Performance of UAV-Based Digital Orthophoto Generation for Emergency Response Applications

Unmanned Aerial Vehicles (UAVs) have been used for accurate orthophoto generation based on advanced Global Navigation Satellite System (GNSS) techniques. In recent years, the UAV systems have become an effective tool for fast monitoring of damages caused by disasters such as the earthquake hazards. The conventional orthophoto generation based on ground control points takes too much time during emergency situations. In the study, different methodologies for the processing of the acquired GNSS Positioning data for direct georeferencing of UAVs were investigated in terms of various orbit products. Evaluating the fitness for emergency response applications, the ground control points (GCPs) also used for validation of the generated orthophoto without using GCPs and based on Precise Point Positioning (PPP) approach. In this study, Ultra-Rapid, Rapid and Final PPP methods based on GNSS observations were used for direct geo-referencing. Thirteen GCPs were located at the study area for the validation of the orthophoto accuracy generated by direct geo-referencing.

Evaluation of Building Vulnerability to Earthquake Using Rapid Visual Screening (RVS) Method

Indonesia is one of the countries prone to earthquakes. One of the earthquake disasters that occurred several years ago hit Palu and Donggala on September 28, 2018. It caused severe damage to infrastructure. Therefore, it is necessary to evaluate buildings vulnerable to earthquakes as a form of prevention. One of the buildings in Jember, the dr. Soebandi hospital, experienced cracks in the walls during an earthquake measuring 6.0 on the Richter scale in Nusa Dua Bali on July 16, 2019. This study carried out the risk assessment of the vulnerability of buildings to earthquakes using the Rapid Visual Screening (RVS) method from FEMA P-154. RVS is a method to identify a building that is potentially vulnerable to earthquake hazards based on visual observations from the exterior and interior of the building. The results of the evaluation using the RVS method showed that the dr. Soebandi hospital is categorized as safe and not prone to earthquakes, with a potential vulnerability percentage of 0.0126%. Based on these results, the building does not require special treatment to anticipate earthquakes; however, maintaining the occupants' safety and extending the building's life requires routine maintenance.

Ground motion models for shallow crustal and deep earthquakes in Hawaii and analyses of the 2018 M 6.9 Kalapana sequence

The damaging 4 May 2018 M 6.9 Kalapana earthquake and its aftershocks have provided the largest suite of strong motion records ever produced for an earthquake sequence in Hawaii exceeding the number of records obtained in the deep 2006 M 6.7 Kiholo Bay earthquake. These records provided the best opportunity to understand the processes of strong ground shaking in Hawaii from shallow crustal (< 20 km) earthquakes. There were four foreshocks and more than 100 aftershocks of M 4.0 and greater recorded by the seismic stations. The mainshock produced only a modest horizontal peak ground acceleration (PGA) of 0.24 g at an epicentral distance of 21.5 km. In this study, we evaluated the 2018 strong motion data as well as previously recorded shallow crustal earthquakes on the Big Island. There are still insufficient strong motion data to develop an empirical ground motion model (GMM) and so we developed a GMM using the stochastic numerical modeling approach similar to what we had done for deep Hawaiian (>20 km) earthquakes. To provide inputs into the stochastic model, we performed an inversion to estimate kappa, stress drops, Ro, and Q(f) using the shallow crustal earthquake database. The GMM is valid from M 4.0 to 8.0 and at Joyner–Boore (RJB) distances up to 400 km. Models were developed for eight VS30 (time-averaged shear-wave velocity in the top 30 m) values corresponding to the National Earthquake Hazards Reduction Program (NEHRP) site bins: A (1500 m/s), B (1080 m/s), B/C (760 m/s), C (530 m/s), C/D (365 m/s), D (260 m/s), D/E (185 m/s), and E (150 m/s). The GMM is for PGA, peak horizontal ground velocity (PGV), and 5%-damped pseudo-spectral acceleration (SA) at 26 periods from 0.01 to 10 s. In addition, we updated our GMM for deep earthquakes (>20 km) to include the same NEHRP site bins using the same approach for the crustal earthquake GMM.

Vulnerability Analysis of Earthquake Hazards in Tasikmalaya City Using Horizontal to Vertical Spectral Ratio (HVSR) Method

Tasikmalaya City is one of the regions in West Java Province that is often hit by earthquakes due to its location near the Indo-Australian Plate subduction zone towards the Eurasian Plate. The surface deposits in this city are alluvium and weakly consolidated step deposits which can cause wave amplification during an earthquake. As a mitigation effort, seismic zoning needs to be carried out to map the areas that will experience heavy damage when an earthquake occurs. This study uses the Horizontal to Vertical Spectral Ratio (HVSR) method which is applied to the microtremor recording data to obtain spatial variations in the predominant frequency and amplification values that can explain the characteristics of the geological layer beneath the surface. Based on the obtained results, the predominant frequency ranging from 0.7 to 9.5 Hz with the lowest frequency distribution in the eastern and northwestern parts, which indicates a thicker sediment layer. Amplification ranging from 1.2 to 12.6 with the distribution of higher values in the eastern, southeastern, and northwestern parts. The inversion of the HVSR curves was carried out to determine the value of shear wave velocity (V s ) in order to obtain a more detailed subsurface geological structure that can be used to determine the level of vulnerability of earthquake hazards. The Neighborhood Algorithm is used to find an optimum model. Based on the results of the inversion process, the V s ranging from 150 - 3054 m/s with lower V s values in the eastern, southeastern, and northwestern parts at depth of about 25 meters. The average value of shear wave velocity at a depth of 30 meters (V s 30) can also be used to determine the type of soil for geotechnical study. From the obtained V s 30data, the types of soil in the research area are classified into moderate soil, hard soil, and rocks.

Integrated Assessment of Urban Land Carrying Capacity (ULCC) for Reducing Earthquake Risk Risaster in Palu City

The land is a natural resource that has limitations to accommodate human activities. Rapid urban population growth, continuous expansion of urban scale, rapid socioeconomic development, and increased pressure on land resources between residents and urban land are monumental contradictions when urban planning does not match land carrying capacity. Assessing urban land carrying capacity is very important to evaluate and obtain an overview of the land capability level by classifying its capacity to be designed according to the area function; to get an overview of the potential and constraints of each land capability class, and to serve as a basis for future regional development. This research was conducted in Palu City, a national urban area in Indonesia. It has limited regional development because it is an area prone to high earthquake disasters. Developing the area requires assessing the land's carrying capacity, especially to minimize the risk of earthquake hazards. The assessment involves three stages of analysis, namely Mapping Earthquake-Prone Areas with Mapping of Earthquake-Prone Areas with seismic micro-zonation; Land Capability Assessment; and Comparative Analysis of Land Capability and City Planning of Palu 2030. This study's results indicate that 74.56% of Palu City is an earthquake-prone area, dominated by land capability classes type A to B, namely low to very low land capability classes (55.42%). Thus, there are physical limitations in urban development. However, suppose it is integrated with the spatial plan of Palu City until 2030. In that case, most (56.07%) are already in accordance with the carrying capacity of their land, especially in protected areas. However, land development still does not comply with their carrying capacity (35%) in cultivation areas with earthquakes. High and covering an area of 24% of the total area of Palu City requires special attention in the development of its area going forward. The requirement that land use plans that do not comply with their carrying capacity must be strictly controlled, especially in high disaster-prone areas.

EVACUATION ROUTING ASSESSMENT DURING EARTHQUAKE OCCURRENCE IN BUTUAN CITY USING GIS TECHNIQUES

Butuan City lies along and is being transected by the Philippine Fault: Surigao Segment. As earthquakes occur more recently, the city is more vulnerable to earthquake hazards, especially soil liquefaction. With the city proper situated mostly on areas susceptible to soil liquefaction and with no constructive evacuation plan against this kind of hazard, it puts the city at risk. This problem highlights the importance of vulnerability assessment for the identification of the road networks that would be most optimal to use in occurrence of an earthquake and an earthquake induced liquefaction. With seven parameters to consider for the assessment, it would be easier to assess by using the pairwise comparison technique of the Analytical Hierarchy Process (AHP) and Geographic Information System (GIS). The analysis was performed by using AHP to assign weights to the parameters and using these weights to classify the road networks into vulnerability classes. The result of the analysis yielded to 34.87% of the road networks with low vulnerability, 65.09% has medium vulnerability and 0.03% are considered to be highly vulnerable. Majority of the road networks especially in the city proper exhibit medium vulnerability in terms of earthquake occurrences. With unavoidable chances that this kind of disaster would happen, these results would benefit the decision makers involved in disaster risk reduction.

Spatial correlation in ground motion prediction errors in Central and Eastern North America

Risk analysis and risk-informed design of spatially distributed infrastructure systems for earthquake hazards require an understanding of and ability to model the spatial correlation of ground motion prediction errors. We assess this spatial correlation in Central and Eastern North America (CENA) by calculating ground motion residuals and semivariograms from earthquake recordings in the Next Generation Attenuation (NGA)-East database. Although data limitations prohibit the development of a reliable model to capture this correlation, we have made notable findings relevant to future risk analyses. The spatial correlation of ground motion prediction errors in CENA is larger than those previously published for shallow crustal regions, which agrees with the lower attenuation observed in CENA. Differences in correlation behavior is also observed between tectonic and induced event recordings. This is, in part, due to the characteristics of the system of stations in which they were recorded. In addition, the choice of ground motion model (GMM) used to calculate the predicted ground motions was found to have an impact on the resulting correlation of errors and we recommend that future CENA spatial correlation models be tailored to the specific infrastructure system and location that will be analyzed.