ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
In order to give full play to the advantages of short construction period of steel structure, composite and non-composite floor slabs with rib height 51 and 76 steel plates are generally used in multi-storey and high-rise steel-bonded truss floor slabs. At the present economic level, the cost of chestnut floor is high, and the floor thickness is 20-30 mm thicker than that of cast-in-situ concrete slab, which makes the surface of the net floor of the building floor uneven. Therefore, the development of other floor systems with self-supporting formwork system of Guang Fan Ben test, the use of concrete floor vertical reinforcement, and bending formed steel welding, forming a small truss that can withstand loads, in the transverse layout of the steel bar bending formed, in the vertical truss above, the bottom of the transverse steel plate and thin steel plate welding, group. The system can bear wet concrete and construction load in the construction stage. In the use stage, the steel truss becomes the steel plate of the concrete floor, which can carry the load. The mechanical model of the through steel formwork is simple and intuitive, and its design is convenient. Before construction, steel skeleton can be designed and prefabricated according to the span and load of the slab; the slab and the slab are interlocked; the formwork is omitted and the construction is convenient.
It has the advantages of rapid construction of prefabricated slabs, large overall stiffness of cast-in-place slabs and good seismic performance, so it has broad application prospects. In this paper, the mechanical properties and ultimate bearing capacity of self-supporting single-way steel formwork in construction and use stages are tested and investigated. It is verified that the theoretical calculation of self-supporting steel formwork design in construction stage l test piece and test device 1.1 test piece adopt single-span simple-supported one-way smooth formwork. There are two groups of specimens: A and B. Fig. 1 is the figure. Fig. 2 shows four group A specimens with a width of 600 mm and a span of 3 m. The distance between the upper and lower longitudinal reinforcement axis is 58 mm, and the lower longitudinal reinforcement center is 25 mm from the bottom steel plate. The bottom bismuth plate of the specimen is ribbed steel plate with thickness of 0.4 mm; the cold drawn low carbon steel wire with abdominal and transverse steel bars of 5 mm and 4 mm respectively: the end vertical bismuth bar is_12; the upper and lower longitudinal steel bars are_12. Plate 25mm.
The bottom steel plate of the specimen is ribbed steel plate with thickness of 0.4 mm; the end vertical bar bar of cold drawn low carbon steel wire with webs and transverse reinforcement of 5 mm and 4 mm respectively is q12: the upper longitudinal reinforcement is q14, and the lower longitudinal reinforcement is_12. 1.2 Groove steel [20 as formwork, pouring concrete] is erected around the test device and loading scheme floor. In the following process: concrete pouring centralized live load (1.5kN) unloading centralized live load (0.56kN in group A, 0.67kN in group B) unloading at the midspan deflection in midspan and strain at each measuring point are recorded respectively, and other abnormal phenomena are observed. For example, in the test, 6 (or 7) strain gauges are arranged at the end of each row of steel bars, the web bar, the middle (or near the middle) of each row of steel bars. (** In the middle where there are web bars or transverse steel bars passing through, one strain gauge is arranged at each side of the middle point, while only one strain gauge is arranged at the middle point.)
Four percentile lateral deflections are arranged at the bottom of each steel plate in the mid-span (or near the mid-span). The strain data are collected by using a jack at the stage of B-bearing capacity test. The jack is used to carry out two-point grading plus concentrated load until the floor is destroyed. The loading diagram is shown in Figure 4. Percentage meters are set at the butt and support of the floor, totaling 3 *2=6, as shown in Fig. 5, and the layout of strain gauges in the floor is shown in Fig. 2.