The collapse of reinforced concrete (RC) frame buildings is mainly caused by the failure of columns. To prevent brittle failure of RC column, numerous studies have been conducted on the seismic performance of strengthened RC columns. Concrete jacketing method, which is one of the retrofitting method of RC members, can enhance strength and stiffness of original RC column with enlarged section and provide uniformly distributed lateral load capacity throughout the structure. The experimental studies have been conducted by many researchers to analyze seismic performance of seismic strengthened RC column. However, structures which have plan and vertical irregularities shows torsional behavior, and therefore it causes large deformation on RC column when subjected to seismic load. Thus, test results from concentric cyclic loading can be overestimated comparing to eccentric cyclic test results, In this paper, two kinds of eccentric loading pattern was suggested to analyze structural performance of RC columns, which are strengthened by concrete jacketing method with new details in jacketed section. Based on the results, it is concluded that specimens strengthened with new concrete jacketing method increased 830% of maximum load, 150% of maximum displacement and changed the failure modes of non-strengthened RC columns.

In the case of columns in buildings with soft story, the concentration of stress due to the difference in stiffness can damage the columns. The irregularity of buildings including soft story requires retrofit because combined load of compression, bending, shear, and torsion acts on the structure. Concrete jacketing is advantageous in securing the strength and stiffness of existing members. However, the brittleness of concrete make it difficult to secure ductility to resist the large deformation, and the complicated construction process for integrity between the existing member and extended section reduces the constructability. In this study, two types of Steel Grid Reinforcement (SGR), which are Steel Wire Mesh (SWM) for integrity and Steel Fiber Non-Shrinkage Mortar (SFNM) for crack resistance are proposed. One reinforced concrete (RC) column with non-seismic details and two columns retrofitted with each different types of proposed method were manufactured. Seismic performance was analyzed for cyclic loading test in which a combined load of compression, bending, shear, and torsion was applied. As a result of the experiment, specimens retrofitted with proposed concrete jacketing method showed 862% of maximum load, 188% of maximum displacement and 1,324% of stiffness compared to non-retrofitted specimen.

In this study, applicability of the steel grid composite deck to temporary or building structure is reviewed. structural performance such as flexural strength, and serviceability is compared with those of the existing deck structures. the result shows that the steel grid composite deck is applicable to horizontal supporting member of temporary of building structure.

Bending tests on the steel grid composite deck with the prefabricated joint were conducted for the evaluation of bending and failure behavior. The joint of deck is composed of concrete shear key and high-tension bolts. Test results show that deck with the joint has a larger load bearing capacity than continuous deck without joint, and the both decks have almost the same punching shear strength.

Experimental tests on the steel grid composite deck were conducted for the evaluation of load transfer mechanism of deck joint which is composed of concrete shear key and high-tension bolts. The results show that the load transfer by concrete shear key is more dominating factor than the high-tension bolts.