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ABSTRACT Bamboo has been widely used as a rapidly renewable structural material to build permanent and temporary structures in past decades. However, the compressive bearing capacity of bamboo is relatively [...]

In order to study the seismic behavior of square concrete-filled steel tubular (CFT) columns with binding bars under cyclic lateral load, numerical simulation is carried out based on the finite element software OpenSEES. The influence factors of seismic performance on square CFT columns with binding bars were studied. The results indicate that the analysis results exhibit good agreement with the experiment data. The axial load level is the main factor that influences the envelope curve. The stiffness decreases with the incresing of axial load level, while the ultimate lateral load increases with the axial load level less than 0.2, and decreases with the axial load level more than 0.3. The thickness of steel tube has a significant influence on the ultimate lateral load, while has little impact on the shape of envelope curve.

Fourteen concrete columns with various sizes confined by BFRP and hybrid FRP and six plain concrete columns as the control specimens were axially loaded to failure in order to investigate both confining effects and size effects in concrete columns confined by BFRP and hybrid FRP. Experimental results show that BFRP and hybrid FRP can increase considerably both the capacity and ductility of the concrete specimens. Furthermore, the peak stress of the unconfined concrete decreases with the size of the specimens increasing. Similarly, the peak stress of BFRP confined concrete decreases with the size of the specimens increasing when the lateral confining stresses are the same. Hence, both confining effect and size effects should be considered carefully in the stress-strain model of concrete confined by BFRP. In addition, both strength and ductility of concrete confined by hybrid FRP in case of CFRP as inner layers and BFRP as outward layers are better than those in case of BFRP as inner layers and CFRP as outward layers.

Eight concrete columns with various sizes confined by CFRP and four plain concrete columns as the control specimens were axially loaded to failure in order to investigate size effects in concrete columns confined by CFRP. Experimental results show that CFRP can increase considerably both the capacity and ductility of the concrete specimens. Furthermore, the peak stress of the unconfined concrete decreases with the size of the specimens increasing. Similarly, the peak stress of confined concrete decreases with the size of the specimens increasing when the lateral confining stresses are the same. Hence, the size effects should be considered in the stress-strain model of concrete confined by CFRP.

Ductility of six L-shaped concrete-filled steel columns with binding bars and one without binding bars were discussed based on the experimental study. A new method based on material properties instead of experimental data was proposed to estimate the ductility of six L-shaped concrete-filled steel columns with binding bars and one without binding bars. Comparison between ductility coefficients based on experimental data and the calculated values by the proposed method shows good agreement.

A new method based on material properties instead of experimental data was proposed to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Comparison between ductility coefficients based on experimental data and the calculated values by the proposed method shows good agreement.

Ductility of concrete-filled steel box columns with binding bars and those without binding bars were discussed based on the experimental study. Two current methods were used to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Results show that binding bars can increase ductility of concrete-filled steel box columns. Ductility of concrete-filled steel box columns with binding bars at closer spacing is considerably better than that of concrete-filled steel box columns without binding bars.