# Study on Bending Performance of Tightly Spliced Truss-Reinforced Plate-Honeycomb Flat Beam
## 1 Introduction  
The steel-concrete composite structure has the outstanding advantages of high strength, convenient construction, and good overall performance, which can ensure the synergistic bearing of concrete and steel under reasonable combination and connection [1]. Among them, the steel-concrete composite beam utilizes the compressive properties of concrete and the tensile properties of steel, which is a high-performance flexural load-bearing component and widely used in floor structures [2]. The traditional steel-concrete composite beam is a T-shaped composite beam formed by placing a concrete slab on the upper flange of a steel beam or a concrete slab on the lower flange of a steel beam to form a composite flat beam, which can usually be divided into two forms of steel sections outside or inside the concrete, as shown in Figure 1. Among them, the steel beam is exposed in the T-shaped composite beam, which requires fireproof and anti-corrosion treatment, and the out-of-plane stability of the steel beam is not guaranteed when its cross-section is high, so extra out-of-plane support is added. In addition, although the T-shaped combination beam has better performance in bearing capacity, the large cross-sectional height of the component causes the overall height of the building to increase, resulting in an increase in construction cost. In order to reduce the aforementioned defects, the combination flat beam places the precast concrete slab on the lower flange of the steel beam, connects the precast base plate with the steel beam as a whole through the cast-in-place layer, and wraps most of the area of the steel beam with concrete, as shown in Figure 2. [PERSON] [3] proposed a new type of wide and large-span steel-concrete composite beam that can be used to reduce the height of the structure. The experimental results showed that as the steel thickness increased by 3 mm, the bending strength of the wide composite steel beam increased by about 20%. In related studies, [PERSON] [4] conducted a flexural analysis of I-beam laminated plate composite beams and established a computational model for I-beam composite beams under vertical loads based on the theory of shear deformation beams. [PERSON] [5] proposed a new type of composite flat beam composed of a wide flange section and laminated plate. The plane section assumption of the composite beam was verified by two concentrated forces loading on the specimen, and the calculation method of flexural bearing capacity was proposed. [PERSON] [6] proposed a flat steel-concrete composite beam and tested its flexural performance. Through the traditional composite beam calculation theory, a simplified calculation model suitable for the bending stiffness and ultimate bending capacity of the model was proposed. [PERSON] [7] established the analysis theory of steel-concrete composite beams considering interface slip and shear deformation in steel and deduced the calculation formulas of the ultimate flexural capacity of simply supported composite beams under uniform load and concentrated load in mid-span, respectively. [PERSON] [8] studied the shear lag effect of steel-concrete composite beams under bending moment and proposed a method to predict the cracking site effect of steel-concrete composite beams. The effectiveness of the method was verified by experimental data. In summary, it can be seen that the flexural bearing capacity of the composite flat beam is mainly related to the effective plate width, the height of the composite flat beam, the beam spacing, and the thickness of the flange plate. The composite flat beam structure has reasonable structure, excellent bearing performance, and certain cost advantages. However, the integrity of the concrete composite plates on both sides is limited due to the form of the web, which is a certain restriction on the layout of the pipeline. The honeycomb beam as the steel component in the combined beam provides a strong condition for solving the connection of the composite plate on both sides of the steel beam.