Axial Compressive Performance of a Composite Concrete-Filled GFRP Tube Square Column

Jiancheng Lu,Yifei Li,Yujun Qi,Xuxu Wang

doi:10.3390/app11156757

Abstract

A composite concrete-filled glass fiber reinforced polymer (GFRP) tube square column is a new type of composite column, where GFRP is externally wrapped over several GFRP square tubes to form a multicavity GFRP tube, and then concrete is poured inside. External GFRP wrapping methods can be divided into two types: entirely wrapped and strip-type wrapped methods. The former is superior to the latter in terms of performance under stress. However, difficulties are introduced in the construction process of the former, and substantial materials are required to wrap the entire structure. To examine the axial compressive performance for this new type of composite column and the impact of the wrapping method, we designed and fabricated one type of entirely wrapped composite column and two types of strip-type wrapped composite columns with clear spacings of 85 mm and 40 mm, respectively, and performed static axial compression tests. Through tests and numerical simulations, we obtained the failure mode, load–displacement curve, and load–strain curve of the specimen, and analyzed the impact of the externally wrapped GFRP on the mechanical behavior of the composite column. The results show that the composite column reached the peak load before the fracture of the GFRP tube fiber occurred, and the bearing capacity declined sharply to approximately 75% of the peak load after the fiber fractured, then entered a platform section, thereby displaying ductile failure. As the wrapped layers of GFRP strips increased, the load capacity of the specimen exhibited a linear growth tendency. Compared with the performance of the entirely wrapped method, the load capacity of the specimens in the W5040 group declined 9.8% on average, and the peak efficiency of the GFRP strips increased by 50%, thereby indicating that the use of appropriate GFRP layers and strip distance intervals can ensure the appropriate bearing capacity of composite columns and full utilization of GFRP material properties.

Highlights

Fiber-reinforced polymer (FRP) tubes, which are characterized by light weight, high strength, corrosion resistance, easy processing, and fatigue resistance, were first applied to military facilities in the US, and to the construction field by British engineers [1,2]
Under the action of axial loading, FRP has a confining effect on the internal concrete such that the composite column is in triaxial compression state, which improves the bearing capacity, second-order stiffness, and ductility of the component [3,4]
Glass fiber-reinforced polymer (GFRP) confined concrete-filled composite square columns were proposed in this study

Summary

Introduction

Fiber-reinforced polymer (FRP) tubes, which are characterized by light weight, high strength, corrosion resistance, easy processing, and fatigue resistance, were first applied to military facilities in the US, and to the construction field by British engineers [1,2]. The sections of pultruded profiles that are currently used are relatively small, thereby making it difficult to directly apply these profiles to composite columns with a large section and large bearing capacity To address this issue, glass fiber-reinforced polymer (GFRP) confined concrete-filled composite square columns were proposed in this study. The use of pultruded GFRP tubing, instead of steel tubing, can improve the specimen’s corrosion resistance, which can be widely used in load-bearing components and sea–sand–concrete structures [14,15] Structures such as beam-column nodes will unavoidably appear in practical engineering. FRP strips wrapped over a beam or column can achieve a good confinement effect They have good application prospects as they allow flexible adjustment between the deformability and strength capacity, less consumption of FRP in engineering, and convenience in mechanical automated construction. The finite element numerical model established in this study performs well in simulating the axial compression stress of the GFRP concrete composite column, and in analyzing the mechanical performance of the proposed composite column under axial compression loading

Specimen Design and Fabrication

Axial Load–Strain Curve

Test Verification

Parametric Analysis

Findings

Conclusions