A rapid mapping of landslides following a disaster is important for coordinating emergency response and limiting rescue delays. A synthetic aperture radar (SAR) can provide a solution even in harsh weather and at night, due to its independence of weather and light, quick response, no contact and broad coverage. This study aimed to conduct a comprehensive exploration on the intensity and coherence information of three Advanced Land Observing Satellite-2 (ALOS-2) SAR images, for rapid massive landslide mapping in a pixel level, in order to provide a reference for future applications. Applied data were two pre-event and one post-event high-resolution ALOS-2 products. Studied area was in the east of Iburi, Hokkaido, Japan, where massive shallow landslides were triggered in the 2018 Hokkaido Eastern Iburi Earthquake. Potential parameters, including intensity difference (d), co-event correlation coefficient (r), correlation coefficient difference ( $∆r$ ), co-event coherence ( $\mathsf{\gamma }$ ), and coherence difference ( $∆\mathsf{\gamma }$ ), were first selected and calculated based on a radar reflection mechanism, to facilitate rapid detection. Qualitative observation was then performed by overlapping ground truth landslides to calculated parameter images. Based on qualitative observation, an absolute value of d ( $d_{abs1}$ ) was applied to facility analyses, and a new parameter ( $d_{abs2}$ ) was proposed to avoid information loss in the calculation. After that, quantitative analyses of the six parameters ( $d_{abs1}$ , $d_{abs2}$ , r, $∆r$ , $\mathsf{\gamma }$ and $∆\mathsf{\gamma }$ ) were performed by receiver operating characteristic. $d_{abs2}$ and $∆r$ were found to be favorable parameters, which had the highest AUC values of 0.82 and 0.75, and correctly classified 69.36% and 64.57% landslide and non-landslide pixels by appropriate thresholds. Finally, a discriminant function was developed, combining three relatively favorable parameters ( $d_{abs2}$ , $∆r$ , and $∆\mathsf{\gamma }$ ) with one in each type, and achieved an overall accuracy of 74.31% for landslide mapping.

In the current research work, an attempt is made to increase the seismic capacity of unreinforced masonry (URM) structures by proposing a new composite material which can improve shear strength and deformation capacity of URM wall systems. Fiber Reinforced Polymer (FRP) having high tensile and shear stiffness can significantly increase in-plane and out-of-plane strength of masonry walls, but, inherently, FRP strengthened wall systems exhibit brittle failure under extreme seismic loading. Polypropylene (PP-band) is a low cost material with sufficient ductility and deformation capacity. Keeping in view the behavior of FRP and PP-band, a composite of FRP and PP-band is proposed for retrofitting of URM walls. Mechanical behavior of the proposed composite material is assessed by carrying out an in-plane diagonal compression test and an out-of-plane bending test on twenty-five 1/4-scaled masonry wall panels. Experimental plan for each panel, URM, PP-band retrofitted, FRP retrofitted and FRP + PP-band retrofitted masonry, is diagonal compression test and three-point bending test. Experimental results have determined that FRP + PP-band composite increased, not only the initial peak strength, but also the ductility, deformation capacity and residual strength of URM wall systems.

The current study is devised to evaluate the seismic performance of fiber-reinforced polymer (FRP) retrofitted buildings with openings at different FRP reinforcement levels. Required objectives are achieved by performing five shake table tests on 1/4-scale models of single-story boxlike masonry buildings. Out of five building models, one was an unreinforced masonry (URM) building model whereas the other four were retrofitted with different quantities and layouts of FRP reinforcement. FRP reinforcement is reduced by decreasing FRP strip widths and strip spacing and applying FRP strips on either the inside or outer faces of walls. Each building model was subjected to the same series of input ground motions with gradually increasing amplitudes. A series of diagonal compression tests was also conducted to decide the appropriate type of FRP and trial FRP reinforcement ratios for the masonry building models. Descriptions of the tested models are provided, including the structural response in terms of ba...

Reinforced concrete (RC) frames are an integral part of modern construction as they resist both gravity and lateral loads in beams and columns. However, the construction methodologies of RC frames are vulnerable to non-engineering defects, particularly in developing countries. The most common non-engineering defect occurs due to improper lap splice, which can compromise the structural integrity. This research demonstrates an easy, low-cost, and verifiable experimental technique incorporating micro-concrete to evaluate the seismic performance of a completely engineered RC frame with the defect of improper lap splice. The micro-concrete was prepared by using the locally available material for a target compressive strength and then two scaled-down RC frames (1/16 scale) were prepared, including one proper frame and another with improper lap splice. Finally, these frames were tested on a shake table to study their behavior under various seismic loading conditions. This study quantifies the severity of high-risk structural systems due to non-engineering defects. The experimental results demonstrate that improper lap splice can alter the frame’s damage points, triggering the failure of the whole structure.

災害時の救急・救援活動や復旧活動に際して自動車の利用は不可欠であり、道路情報は最も重要な情報の一つである。しかし、大きな災害に際しては、刻々と変化する広域の道路状況をリアルタイムに把握することは容易ではなく、適切な情報が提供されているとは言い難い状況である。本稿では、プローブカー情報の減災利用に関する取り組みの一環として、2007年7月新潟県中越沖地震における「通れた道路マップ」の試験提供の取り組みについて報告するとともに、抽出された課題を提示した。さらに、プローブカーによる道路被害把握の可能性についても実データに基づき検討し、プローブカー情報の減災利用の実現に向けた課題と展望について議論した。