Bearing Capacity of Recycled Self-Compacting Concrete-Filled Circular Steel Tubular Long Columns Subjected to Axial Load

Feng Yu,Wei Huang,Jie Song,Yuan Fang,Jingfeng Wang,Shaojing Bu ,Wan Hai-Ying ,Wanyu Shen

doi:10.1155/2021/4170705

Abstract

To investigate the ultimate bearing capacity and deformation of the recycled self-compacting concrete-filled circular steel tubular (RSCCFCST) long columns subjected to axial load, nine specimens with different recycled self-compacting concrete (RSCC) strength grades and slenderness ratios are tested. The experimental results indicate that the lateral deflection dominates the buckling failure of the specimens. The ultimate bearing capacity of the specimens is enhanced gradually as the RSCC strength grade increases but decreases as the slenderness ratio rises. The load-strain curves are linear and basically coincide at the elastic stage. The decrease in the slenderness ratio or increase in the RSCC strength grade contributes to the improvement of the stiffness and ultimate circumferential and axial strains of the columns gradually. Based on the combined tangent modulus theory and bearing capacity of the RSCCFCST short columns, two estimation models are presented to predict the ultimate bearing capacity of the RSCCFCST long columns. Additionally, comparisons between the calculation results of the ultimate strength demonstrate that the prediction models established in this study are more accurate than the other specifications mentioned.

Highlights

With the economic development and urbanization over the last decades, a huge amount of construction and demolition wastes was generated. ere are 40 countries in the world whose annual construction and demolition waste production exceeds 3.0 billion tons until 20
Failure Modes. e failure modes of RSCCFCST specimens are presented in Figure 4. ree stages were approximately divided into the loading and failure process. e first stage, named the elasticity phase, lasted longer as the recycled self-compacting concrete (RSCC) strength grade increased and shorter as the slenderness ratio grew
For the long columns, the development of the longitudinal strains became slow at the tension side and fast at the compression side when loaded to 70% of the ultimate strength. e increase of the vertical displacement was obviously accelerated and the deflection was observed in the midspan of the columns

Summary

Introduction

With the economic development and urbanization over the last decades, a huge amount of construction and demolition wastes was generated. ere are 40 countries in the world whose annual construction and demolition waste production exceeds 3.0 billion tons until 20. Ere are 40 countries in the world whose annual construction and demolition waste production exceeds 3.0 billion tons until 20. In China, almost 1.6–1.8 billion tons of construction and demolition waste is produced every year. Omas [8] and Dimitriou [9] found that the failure mode of RAC was similar to the ordinary concrete, and the compressive strength of RAC can be improved by adjusting the water-to-cement ratio and optimizing the mix ratio. Laserna [10] pointed out that the elastic modulus and compressive and tensile strength of RAC decreased with the increase of the replacement rate of RA. Some scholars conducted experiments and illustrated that the mechanical properties of RAC prepared by modified RA were better than those of ordinary concrete [11,12,13]. Limbachiya [14] illustrated that the durability of RAC can be improved by adding an appropriate amount of fly-

Methods

Results

Conclusion