Corrosion level of reinforcing bar is investigated in this study. Seventy-two specimens are designed with 12 different target corrosion levels, two types of reinforcing bars, 3 different concrete covers. Corrosion current density, corrosion potential and ohmic resistance of concrete are measured on these specimens using Gecor device. Metal loss measurements are performed in accordance with ASTM G1-90[1], method C3.5[2], after specimens cracked. The actual corrosion weight loss of the steel reinforcing bars is then compared to the result obtained from the corrosion level measurement. Finally, the estimation of corrosion level can be made using electrical potential and current intensity measured. The experimental results show that the actual corrosion levels of steel bars embedded in concrete are less than the expected corrosion levels. And non-destructive corrosion measurement technique is applicable in order to assess corrosion level in reinforcing bars. This study suggests the relationship between corrosion level and measured electrical potential and measured current intensity.

Before incorporating the earthquake-resistance design in design code(1988), most of existing residential buildings were built without having lateral resistance capacity in addition to their structural peculiarity such as exterior stair ways, exterior elevator room. For these reasons, the retrofitting research demands for existing buildings arise recently and many retrofitting methods are proposed. These tasks are irnportant to reduce the enormous economic loss and environmental issues. The objective of this study is to predict the perforrnance increase due to various strengthen schemes and suggest adequate strengthen methods for wall type apartment buildings not designed to resist earthquake.

Void slab is a slab with hollow portions in the center of the slab which reduce a self weight of the slab. The flexural capacity of void slab is almost same with a normal slab, but the shear capacity is reduced according to the increasing of hollow portion. One of the solutions to improve shear capacity is using shear reinforcing bars. In this study, the shear capacity of one-way void slabs is evaluated according to an effective cross section and the capacity of shear reinforcing bars is discussed depending on integration method. As a result, it is shown that the shear capacity tends to be reduced from 0% to 34.5% of hollow rate and slightly increased from 34.5% to 40.0%. And the capacity of integrated shear reinforcing bars are better than the one without integrated shear reinforcing bars.