Experimental Investigation of the Seismic Performance of Rectangular Reinforced Concrete Columns Subjected to Combined Flexure-torsion Cyclic Loading

Author(s):  
Nahid Attarchian ◽  
Nader K. A. Attari ◽  
Zakariya Waezi
2010 ◽  
Vol 163-167 ◽  
pp. 2267-2273 ◽  
Author(s):  
Hong Ying Dong ◽  
Wan Lin Cao ◽  
Jian Wei Zhang

Two 1/6 scale core walls, including one RC core wall with steel tube-reinforced concrete columns and concealed steel trusses and one conventional RC core wall, were tested under eccentric horizontal cyclic loading. The load-capacity, ductility, hysteresis characteristics, stiffness, stiffness deterioration process, energy dissipation and damage characteristics of the two specimens were compared and discussed in this paper. It shows that the seismic performance of the RC core walls under combined action could be improved by setting the concealed steel trusses in the walls and using the steel tube-reinforced concrete columns as the boundary elements.


Author(s):  
Ehab El-Salakawy ◽  
Fangxin Ye ◽  
Yasser Mostafa Selmy

Composite materials like glass fiber-reinforced polymer (GFRP) is becoming widely acceptable to be used as a reinforcing material due to its high ultimate tensile strength-to-weight ratio and excellent resistance to corrosion. However, the seismic behavior of GFRP-reinforced concrete columns has not been fully investigated yet. This paper presents the results of a numerical analysis of full-size GFRP-RC rectangular columns under cyclic loading. The simulated column depicts the lower part of a building column between the foundation and the point of contra-flexure at the mid-height of the column. GFRP reinforcement properties and concrete modeling based on fracture energy have been incorporated in the numerical model. Experimental validation has been used to examine the accuracy of the constructed finite element models (FEMs) using a commercially available software. The validated FEM was used to perform a parametric study, considering several concrete strength values and axial load levels, to study its influence on the performance of the GFRP-reinforced concrete columns under cyclic loading. It was concluded that the hysteretic dissipation capacity deteriorates under high axial load level due to severe softening of the concrete. The FE results showed a substantial improvement of the lateral load-carrying capacities by increasing concrete compressive strength.


2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Chunyi Yu ◽  
Hua Ma ◽  
Yongping Xie ◽  
Zhenbao Li ◽  
Zhenyun Tang

The size effect on the seismic performance of conventional reinforced concrete columns has been observed in terms of flexural failure and shear failure. Under earthquake loading, slender columns experience flexural failure, and short columns experience flexure-shear failure and shear failure. However, the effect of section size on the seismic performance of high-strength reinforced concrete columns under the conditions of different shear span-to-depth ratios requires further confirmation. For this purpose, six high-strength reinforced concrete columns with shear span-to-depth ratios of 2 and 4 were subjected to cyclic loading in this study. The experimental results indicated that relative nominal flexural strength, energy dissipation coefficient, factor of safety, and local factor of safety all exhibited a strong size effect by decreasing with increasing column size. Furthermore, the size effect became stronger as the shear span-to-depth ratio was increased, except for average energy dissipation coefficient. The observed changes in the factor of safety were in good agreement with the Type 2 size effect model proposed by Bažant. Thus, based on the local factor of safety and Bažant’s Type 2 model, the code equation for moment capacity of different shear span-to-depth ratios was modified to provide a consistent factor of safety regardless of column size.


2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Chichaya Boonmee ◽  
Kittipoom Rodsin ◽  
Krissachai Sriboonma

This paper aims at investigating gravity load collapse behavior of extremely poor quality reinforced concrete columns under cyclic loading. Such columns were usually constructed by local people and may not be designed to meet any of the standards. It was found that their concrete strength may be as low as 5 MPa and the amount of longitudinal reinforcement may be lower than 1%. This type of column is deliberately defined as “nonengineered reinforced concrete column,” or NRCC. During earthquake, the gravity load collapse of the NRCC columns caused a large number of death tolls around the world. In this study, four columns as representative of existing NRCC were tested under cyclic loading. The compressive strength of concrete in order of 5 MPa was used to be representative of columns with poor quality concrete. Two axial load levels of 6 and 18 tons were used to study the influence of axial load level on maximum drift at gravity load collapse. To investigate the effect of bar types on drift capacity, 9 mm round bars were used in two specimens and 12 mm deformed bars were used for the rest of the specimens. The maximum drift before gravity load collapse was very dependent on the axial load level. The maximum drift of the specimens subjected to high axial load (18 tons) was extremely low at approximately 1.75% drifts. The use of deformed bars (associated with larger amount of longitudinal reinforcement) caused the damage to severely dissipate all over the height of the columns. Such damage caused columns to collapse at a lower drift compared to those using round bars. Finally, the plastic hinge model was used to predict the maximum drift of the low strength columns. It was found that the model overly underestimates the drift at gravity load collapse.


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