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On September 28, 2018, Palu city in the Central Sulawesi area, suffered the M7.5 earthquake. An epicenter of its earthquake located 77 km from the capital of Central Sulawesi Province, Palu city. The main earthquake, followed by a localized 4 to 7 meters high tsunami, which swept shore-lying houses and buildings on its way. A large number of damages on reinforced concrete (RC) buildings, houses, and soil liquefaction spread in Palu city were observed after the earthquake. The post-earthquake observation, as is reported in this paper, was conducted in order to define the typical pattern of the buildings' damages. The field investigation was focused on the damaged RC frame of buildings' structures. Several types of damage were detected on RC structures such as collapse due to the soft story, damage to beam-column joint, failure of short column, shear failure of the column, and collapsed of brick masonry infills. Two damaged RC frame buildings, i.e., one was severely damaged and the other in totally collapsed, were furthermore analyzed to define their seismic capacity based on Japanese standard. According to the analyses of the first story in these buildings, the distinct difference of seismic performance of both buildings was discovered. The severely damaged building had a higher lateral strength index when compared to the collapsed building because of its structure able to maintain the lateral strength within large deformation. [ABSTRACT FROM AUTHOR]

The collapse of the brick masonry infill in the Reinforced Concrete (RC) structures has been known as one of the causes of the many casualties during the earthquake. This clay brick masonry has been commonly used as partitions in the RC frame structures in earthquake-prone areas such as West Sumatera, Indonesia. Strengthening the brick masonry infill is expected to be able to increase the performance of the brick masonry against the earthquake motions, which also may improve the seismic performance of RC structures. In this study, four of 1/4 reduced-scale singe-bay and single-story RC frame specimens were prepared and tested under lateral static reversed cyclic loading. The specimens include one specimen of RC frame infilled with brick masonry and three specimens of RC frames infilled with strengthened brick masonry. Strengthening of the brick masonry infill has used three types of wire mesh, namely plastic wire mesh, steel wire mesh, and chicken wire mesh. The wire mesh was tacked on both sides of the diagonal area of the brick masonry infill. The wire mesh was then fastened to columns and beams of the RC frame by using chemical epoxy adhesive. The purpose of this experimental study is to define an effective, inexpensive, and easy to apply the strengthening of the brick masonry infill such that it may be applied by the local labors in West Sumatera, Indonesia. The structural test results have shown that all the strengthening methods increase the lateral strength of the RC frame and can delay the failure of the brick masonry infill. Even though the strengthening by using the steel wire mesh produced a higher increase in stiffness of the specimen compares to others, however strengthening by using chicken wire mesh performed the most effective strengthening method. The presence of the chicken wire mesh maintains the ductility of brick masonry infill and the RC frame as well. [ABSTRACT FROM AUTHOR]