The term CFRP concrete-filled steel tube refers to a structure formed by pouring concrete into CFRP steel composite tubes [
1,
2,
3]; it also refers to a structure formed by reinforcing or repairing concrete-filled steel tubes with CFRP [
4,
5,
6]. The existence of CFRP can improve the durability of concrete-filled steel tubes, and CFRP can also delay the buckling deformation of steel tubes. Furthermore, in terms of its mechanical properties, CFRP has high tensile strength; so, for concrete, in addition to the constraints of steel tubes, CFRP can also provide good constraint effects and improve its mechanical properties. In engineering practice, structural members mainly bear axial loading, bending moment, compression bending, and other loads, but sometimes, the bending–shear force cannot be ignored—for example, in stub columns supporting spatial latticed shells, piers with large section sizes, nodes with slant supports, etc., and structures under transverse loads such as those caused by earthquakes, blasts, and impacts can also be subject to higher bending–shear loads [
7,
8,
9,
10,
11].
Many research results have been presented on CFRP concrete-filled steel tubes, including experimental research, finite element simulations, theoretical analyses, bearing capacity calculation/related equations, and restoring force models. Yu et al. [
12] analyzed existing experimental data and proposed a calculation expression for the bearing capacity of FRP concrete-filled steel tubes. Research has found that the mechanical characteristics of FRP concrete-filled steel tubes mainly depend on the equivalent constraint coefficient before FRP failure [
13]. Tao et al. [
14] conducted experiments on the bending performance of CFRP-reinforced, concrete-filled steel tubes after a fire; the experimental results indicated that the repair effect of CFRP on flexural specimens is not as good as that on axially compressed short columns, perhaps due to the absence of longitudinal CFRP. Yu et al. [
15] established 12 numerical models using ABAQUS 6.1.14 to study the effect of the slenderness ratio on the mechanical performance of CFRP-confined, concrete-filled steel tube long columns; the analysis results indicated that as the slenderness ratio increased, the bearing capacity, stiffness, and maximum equivalent stress value of the steel tube specimen decreased, and the steel tube hoop effect weakened. Du et al. [
16] conducted axial compression performance tests on rectangular high-strength, concrete-filled steel tube long columns constrained by CFRP, with experimental parameters including the slenderness ratio, the width thickness ratio of specimen cross-section, concrete strength, and the number of CFRP layers. Sundarraja et al. [
17] studied the strengthening effect of CFRP on concrete-filled steel tube bending members, with a total of 18 specimens. At the same time, a nonlinear finite element model was established to verify the stress–strain relationship curve and corresponding failure modes. The research results show that some specimens pasted with CFRP were damaged due to the peeling of CFRP, and some did not even reach the corresponding bearing capacity of the steel tube concrete specimens. However, specimens pasted with CFRP along their entire lengths had significantly improved bending bearing capacities and stiffnesses. Al Mekhlafi et al. [
18] conducted eccentric compression tests on 12 CFRP-restrained stainless steel-reinforced concrete short columns and established a three-dimensional finite element model for numerical simulations based on the tests. Chen et al. [
19] studied the impact performance of FRP-reinforced steel tube concrete and analyzed the dynamic performance of various types of FRP-reinforced steel tube concrete with different steel tube thicknesses under lateral impact under different load conditions using a finite element model. The results indicated that FRP steel tube concrete has a higher bearing capacity and better toughness, making it more suitable for structures subjected to impact loads. Cai et al. [
20] tested the stress performance of six full-scale cantilever specimens under the combined action of a constant axial force and lateral hysteresis displacement, including CFRP-reinforced concrete pipes. One GFRP tube-reinforced concrete specimen and one thin-walled steel tube-reinforced concrete specimen, as well as two GFRP thin-walled steel tube-reinforced concrete specimens were used. The experimental results indicated that GFRP limits the occurrence of the local buckling of steel pipes and the sudden failure of welds due to excessive biaxial stress. When the axial compression ratio increases from 0.2 to 0.45, the displacement ductility of GFRP steel tube concrete remains almost unchanged.
This type of structure is widely used in bridges and other structures, but there is currently limited research on the bending–shear coupling load of concrete-filled CFRP steel tubes, and there is no reasonable finite element model. In view of this, a testing device and method for structural members under bending–shear loads have been developed. We conducted relevant experimental research with the shear span ratio and CFRP layers as the main parameters to investigate the influence of these parameters on the shear–bearing capacity and stiffness of the specimen, and we proposed the use of the moment shear correlation equation for concrete-filled CFRP steel tube bending–shear members.