Research on the Estimation Method of the Stiffness Degeneration Index of Reinforced Concrete Members

Yukui Wang,Xiao Zheng,Jian Wang,Weijun Yang,Zhefeng Liu

doi:10.1155/2020/9464275

Abstract

Based on variable amplitude displacement cycle tests of 24 reinforced concrete members with different reinforcement conditions, the stiffness degradation index was proposed to describe the damage. The relationship between the stiffness degradation index, the displacement history, and the cumulative energy dissipation was studied; on this basis, an estimation method for the stiffness degradation index was proposed. By comparing the experimental values and estimated values of the stiffness degradation index, the proposed method provides promising prediction reliability and accuracy. The stiffness degradation index has an effective relationship with the structural design parameters. Based on the stiffness degradation index, the reinforced concrete members can be divided into five performance levels: no damage (DK,k < 0), mild damage (0 < DK,k ≤ 0.3), moderate damage (0.3 < DK,k ≤ 0.7), severe damage (0.7 < DK,k ≤ 0.9), and destruction (0.9 < DK,k ≤ 1), which can provide a good reference for the seismic design of reinforced concrete members. The increase in the transverse reinforcement ratio can significantly reduce the stiffness damage, and the effect is more obvious under the conditions of small ductility. Under the same conditions, the smaller the ductility condition is, the smaller the stiffness damage of the reinforced concrete members will be. Therefore, the control of the ductility condition and the increase in the transverse reinforcement ratio are stable and effective methods for controlling the stiffness damage of reinforced concrete members.

Highlights

In performance-based design methods, the determination of the structural performance levels is based on the damage index [1,2,3]
In 1986, Park and Ang [5] proposed the Park-Ang damage index by linearly combining the deformation damage term with the energy damage term. e damage index has an effective relationship with the structural design parameters, which can provide a good reference for seismic design [6]. erefore, an increasing number of applications have been obtained [7]
The influence of the difference displacement path is not considered in the damage index, while the deformation capacity and energy dissipation capacity of the structure are related to the displacement history [8, 9]

Summary

Introduction

In performance-based design methods, the determination of the structural performance levels is based on the damage index [1,2,3]. These revisions do Advances in Civil Engineering not touch on the influence of the variable amplitude displacement history on the damage development, which causes the verification of the revised damage index to lack sufficient theoretical support Another type of damage index describes the damage according to the change in the structural characteristics before and after damage, such as the stiffness [12,13,14], period [15], and deformation energy [16]. E relationship between the stiffness degradation index and the energy dissipation capacity, displacement path, and structural design parameters was studied On this basis, an estimation method of the stiffness degradation index was proposed, which is intended to provide a reference for seismic design and damage assessment of reinforced concrete members in the future

Experiments

The Stiffness Degradation Index of the Reinforced Concrete Members

Conclusions