Study of the Cyclic Behavior of New RC Columns with Different Types of Hoops

Nowadays, construction of high-rise buildings become a trend in order to deal with the high population. As the story increase, lower-story structure members will carry higher loads because of the higher self-weight especially for column members. Comparing with steel structure, reinforced concrete structure has a deadly weakness - heavy weight. In order to overcome the problem, bigger section will be used. However, the large dimension was consequent on the higher price and the smaller space. According to the experience of Japan, using high-strength materials in RC members can reduce the dimensions effectively. Therefore, high-strength materials such as high-strength concrete and high-strength steel were strongly recommended in construction industry.
Many researches mention that the shear capacity of RC columns will reduced as the lateral deformation increase especially for columns with high-strength materials. For the reason that the amount and type of transverse reinforcement used in RC columns is a critical factor. For now there is no research of high-strength concrete columns with gas pressure welded rebars as transverse reinforcement in Taiwan. This study used conventional closed-shape hoops with 135° hooks and 90°-135° conventional tie as samples, comparing with welded closed-shape hoops made by gas pressured. Investigating the cyclic behavior of New RC columns with different types of hoops and verifying the adequacy of current ACI shear design equations of RC columns with high strength steel and concrete are the objectives of this study in order to facilitate the analysis and application.