Modular design method based on CS-FC-SB composite wall

Abstract

The invention discloses a modular design method based on a CS-FC-SB composite wall body. The modular design method comprises the following steps: decomposing a CS-FC-SB wall into a foamed concrete wall (CS-FC) with a cold-formed steel frame, an outer-layer ecological straw board (SB) and an end post for respective design, and finally designing a connection mode. Wherein the CS-FC size, reinforcement and foamed concrete model selection are obtained on the basis of a performance design method, the SB thickness is obtained on the basis of a finite element analysis method, and the end column size reference specification structure, welding, self-tapping screw or bolt connection and other key parameter design are obtained on the basis of an anti-seismic requirement simplified calculation formula of the CS-FC-SB composite wall. By means of the modular design method, the computational analysis process of the CS-FC-SB composite wall can be greatly simplified, only computational welding, self-tapping screws and bolt connection are needed on site, the construction period can be effectively shortened, the construction cost is reduced, and the method can be applied and popularized in low multi-layer village and town building structures.

Description

Technical Field

[0001] The present invention belongs to the field of construction, and specifically relates to a modular design method based on a CS-FC-SB combined wall, wherein a foamed concrete wall with a cold-formed steel frame is referred to as CS-FC, and an outer ecological straw board is referred to as SB. Background Art

[0002] At present, most of the building structures in villages and towns are masonry, brick-concrete and cold-formed steel structures. The former two have poor integrity due to their long construction age and lack of reasonable design, while cold-formed steel structures have poor sound insulation and thermal insulation effects. Foamed concrete is a lightweight porous cement-based material with the advantages of light weight, thermal insulation, sound insulation, green environmental protection, good fire resistance, strong energy dissipation and earthquake resistance. In recent years, it has gradually been applied to village and town buildings as a shear wall structure.

[0003] However, the discreteness of foamed concrete materials is large, and the quality of the wall depends on the level of engineering casting. Therefore, the foamed concrete shear wall structure is usually prefabricated in the factory and then assembled on site. The assembly method often uses mortar, reserved steel bars or shear keys to connect, and the process is complicated. The construction and connection of prefabricated walls are mostly based on the experience of designers, and there is no corresponding design method.

[0004] In recent years, as the country pays more attention to village and town buildings, the design requirements of village and town foamed concrete shear walls have also changed from a single safety indicator to comfort and multi-function. Walls of different shapes such as cross-shaped and T-shaped walls, reliable connection methods, and mature and convenient design methods have become new requirements for foamed concrete shear walls.

[0005] The present invention proposes a CS-FC-SB combined wall. It includes a cold-formed steel frame and end columns for welding and assembly, an outer layer of ecological straw boards, and an inner layer of foamed concrete, wherein ribs are welded on the inner side of the cold-formed vertical steel web, and the straw boards are embedded in the rib grooves. The straw boards and the vertical and horizontal cold-formed steel form a closed space for pouring foamed concrete. The cold-formed steel, foamed concrete and ecological straw boards together form a combined force system. At the same time, the foamed concrete and ecological straw boards are lightweight thermal insulation materials, which can make the combined wall have good thermal insulation performance and are easy to maintain in the later stage. In order to further promote its use, a corresponding design method is urgently needed. Therefore, the present invention proposes a modular design method for a CS-FC-SB combined wall. Summary of the invention

[0006] To solve the above problems, the present invention discloses a modular design method based on a CS-FC-SB combined wall. The above modular design method can greatly simplify the calculation and analysis process of the CS-FC-SB combined wall. Only welding, self-tapping screws and bolt connections need to be calculated on site, which can effectively shorten the construction period and reduce the construction cost. It can be promoted and applied in low-rise and multi-story village and town building structures.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A modular design method based on CS-FC-SB combined wall, in which a foamed concrete prefabricated wall with a cold-formed steel frame, an end column, and an outer ecological straw board are designed separately. When the above module designs are completed and assembled, only the connection nodes between the end column and the foamed concrete prefabricated wall need to be designed.

[0009] The CS-FC-SB combined wall comprises a foamed concrete prefabricated wall with a cold-formed steel frame, an end column, an outer ecological straw board and a connection node. The prefabricated wall comprises a square cold-formed steel frame for welding and assembly, an embedded vertical cold-formed steel for fixing the straw board, a vertical brace for preventing the straw board from expanding outward and an inner foamed concrete. The end column is a steel section or a steel tube concrete column. The end column and the steel frame of the foamed concrete prefabricated wall can be connected by reserved bolts, studs or welding. The foamed concrete prefabricated walls I, II, III and IV with cold-formed steel frames can be connected in an angle, T-shaped or cross-shaped manner.

[0010] The design of the foamed concrete prefabricated wall with cold-formed steel frame is divided into compressive bearing capacity design and shear bearing capacity design. The compressive bearing capacity design is designed using formula (1), and the shear bearing capacity design value is designed using formula (2).

[0011] N c =0.2ζf c bh (1)

[0012] V wh =(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ (2)

[0013] The thickness of the outer ecological straw board is selected and calculated using formulas (3) and (4). The formula can be discretized and calculated using the finite element method, and the design is performed based on the maximum stress value under the allowable displacement angle.

[0014] The end column is selected in size according to the standard construction requirements. If the structural column is a concrete column, the concrete specification GB 50010 can be referred to, and if it is a steel column, the steel structure specification GB 50017 can be referred to. If it is a reserved bolt stud connection, the structural measures of the embedded parts in the concrete column must still meet the requirements of GB 50010.

[0015] After the above connection form design is completed, the connection node becomes a weak point. According to the adopted node form, the corresponding design method is carried out. The calculation formula is shown in formula (5) and (9):

[0016] l weld =max{min(l1,l2),l3} (5)

[0017] N=max{N1,N2} (9)

[0018] The beneficial effects of the present invention are:

[0019] According to the modular design method based on the CS-FC-SB combined wall described in the present invention, the cold-formed steel-foamed concrete-ecological straw board assembled combined wall is produced, which reduces the air pollution caused by straw burning, turns waste into treasure, and is rolled at high temperature and high pressure without polluting materials such as glue. The straw board has good bending resistance and thermal insulation performance, and can also serve as a template for internally filled foam concrete in the combined wall. The internally filled foamed concrete has excellent thermal insulation performance and is lightweight, reducing the weight of the combined wall. Straw boards and foamed concrete can effectively avoid local buckling of cold-formed steel frames. Through the reasonable combination of the outer straw board and the internally filled foamed concrete, the standard of 65% energy saving for buildings in hot summer and cold winter areas can be achieved, and it can withstand vertical pressure and horizontal shear force, has good seismic resistance, and can achieve structural enclosure-insulation integration.

[0020] The modular design method proposed in the present invention can greatly simplify the calculation and analysis process of the CS-FC-SB combined wall. Only welding, self-tapping screws and bolt connections need to be calculated on site. The modules are prefabricated in the factory, without post-casting strips and on-site wet operations. The on-site assembly is convenient and efficient, which can effectively shorten the construction period, turn waste into treasure, and reduce the construction cost without the construction of a later building insulation layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the design drawing of the present invention.

[0022] Figure 2 This is a top view of module I.

[0023] Figure 3 Schematic diagram of the cold-formed steel frame of module I.

[0024] Figure 4Schematic diagram of the vertical steel ribs of module I.

[0025] Figure 5 Schematic diagram of the vertical cold-formed steel of module I.

[0026] Figure 6 This is the top view of module II.

[0027] Figure 7 Schematic diagram of the frame of module II with holes for module I and the end column frame.

[0028] Figure 8 This is a cross-sectional view of module I and the end column with holes in the frame of module II.

[0029] Fig. 9 This is a structural diagram of a straight-line wall.

[0030] Fig.10 This is the structural diagram of the corner wall.

[0031] Fig.11 This is the T-shaped wall structure diagram.

[0032] Fig.12 This is a diagram of the cross-shaped wall structure.

[0033] Fig.13 This is a three-dimensional diagram of a T-shaped wall.

[0034] List of Figure Symbols:

[0035] 1. Cold-formed steel frame, 2. Vertical cold-formed steel, 3. Tie rods, 4. Outer ecological straw board, 5. Foamed concrete, 6. Box-type end columns, 100, self-tapping screws; 101, vertical steel ribs; 102 horizontal U-shaped steel; 1010 upper and lower end ribs; 1020, equally spaced holes; 1021, elliptical hole one; 201, elliptical hole two; 601 and 602, vertical U-shaped steel; 6010, elliptical hole three. DETAILED DESCRIPTION

[0036] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. (The calculation methods for the straight, T-shaped, and cross-shaped types are similar, and they are explained together at the end)

[0037] Embodiment 1:

[0038] A CS-FC-SB combined wall comprises a cold-formed steel frame 1 for assembly. The cold-formed steel frame 1 is provided with a vertical steel rib 101 for fixing a straw board 4. The outer ecological straw board 4 is clamped in the vertical steel rib 101, and a vertical cold-formed steel 2 is embedded inside. A pull rod 3 is arranged on the outside. The cold-formed steel frame 1 can be used for welding or connected into a wall group using L-shaped steel sheets.

[0039] Embodiment 2:

[0040] According to a CS-FC-SB combined wall described in Example 1, the cold-formed steel frame 1 includes a vertical cold-formed steel welded with a rib 101, which is used to clamp the straw board 4; the embedded vertical cold-formed steel 2 can prevent the straw board 4 from being concave, and at the same time improve the vertical steel matching ratio. The vertical tie rods 3 on the outside of the straw board 4 can prevent the straw board from bulging outward during pouring. The cold-formed steel frame 1 is fixed to the straw board 4 by self-tapping screws 100. The upper horizontal U-shaped steel 102 is densely covered with evenly spaced holes 1020, which are used to pour and fill the foamed concrete to form module I, such as Figure 2 shown.

[0041] Embodiment 3:

[0042] Making the frame of the frame with holes module I: Based on Example 2, the length of the upper and lower horizontal U-shaped steels 102 is increased by the width of the box-shaped end column 6. The two vertical U-shaped steels 601 and 602 are welded relative to each other through the I-type weld to form the box-shaped end column 6, which is stuck in the upper and lower horizontal U-shaped steels 102. The side contact surface of the frame with holes module I and the box-shaped end column is provided with an elliptical hole 1021 corresponding to the elliptical hole 3 6010, which is used to pour the foam concrete filled inside and form a through hole. The concrete is poured from the equally spaced holes 1020 of the upper horizontal U-shaped steel 102, and the concrete extends all the way to the box-shaped end column 6 to form module II, such as Figure 6 shown.

[0043] The prefabricated modules I and II can meet the requirements of long walls, corner walls, T-shaped walls and cross-shaped walls through design and assembly. The modules can be connected by I-shaped welds or L-shaped steel sheets.

[0044] Embodiment 4:

[0045] Long walls, corner walls, T-shaped walls, and cross-shaped walls are formed by prefabricating modules I and II and welding them with type I welds or connecting them with L-shaped steel sheets on site. Fig.13 As shown, the steel sheet and the module are connected by self-tapping screws. The self-tapping screws are arranged at a spacing according to the specification, and an L-shaped steel sheet is arranged every 500mm along the vertical direction. The composite wall and the steel beam or cold-formed steel composite beam can be connected by welding or bolting. When bolting, screws must be embedded in module I and module II, and the corresponding steel beam or cold-formed steel composite beam must be embedded in the steel casing corresponding to the screw. The screw passes through the steel casing and the end is fixed with a nut.

[0046] Design Methodology:

[0047] (1) According to the above wall structure, the pressure N1 and shear design value V1 of the single wall are obtained in the professional design software (Note: Here is the design value obtained under a certain load rather than the bearing capacity design value), assuming that the wall section height is h. When the foamed concrete grade is 500kg / m3 When the compressive strength f c 4MPa, E c is the elastic modulus of foam concrete under pressure, which is 19 GPa. The minimum wall thickness b can be determined by the following formula: min , must meet the following requirements:

[0048] N1≤Nc;b1≥N1 / (0.2ζf c h)

[0049] V1≤(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cos(1 / 100)

[0050] b2≥{V1 / (0.95+0.07λ1+0.025λ2) / cos(1 / 100)-0.26N c} / 0.077f c h

[0051] b min =max(b1,b2)

[0052] ζ is the correction factor for compressive bearing capacity of embedded vertical cold-formed steel considering the constraint effect of straw board. According to the test and finite element simulation results, the correction factor is taken as 1.05 (E s A s / (E c b min h));

[0053] E s is the elastic modulus of the embedded vertical cold-formed steel;

[0054] A s is the cross-sectional area of ​​the embedded vertical cold-formed steel;

[0055] f c is the compressive strength of foam concrete prism, unit: MPa;

[0056] h is the height of the wall section;

[0057] (2) When the straw board size is known and the thickness is determined by using the finite element method and discrete formula 3, the bottom boundary is taken as rigid connection, the board thickness is 1, the top forced displacement is 0.01H, and the maximum strain is σ max , the design thickness d of the ecological board meets:

[0058] d>f vh / σ max

[0059] (3) The end column structure can be determined according to relevant specifications.

[0060] (4) After the above three steps are completed, the design of all prefabricated parts of the CS-FC-SB composite wall can be realized. These parts are processed in the factory and transported to the site. Only the weld length and the number of bolts or studs need to be determined later.

[0061] (5) Formulas 5 and 9 can be used to determine the corresponding weld length, weld leg size, number of bolts, bolt diameter, and bolt strength, and finally realize the modular design method of the CS-FC-SB composite wall.

[0062] For welded joints, the weld leg size h f It can be 4mm or 5mm, and the total length of the weld is calculated as follows

[0063] l weld =max{min(l1,l2),l3} (5)

[0064] l1={1.05(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ} / f tw h f (6)

[0065] l2=0.8NsH (7)

[0066] l3=60h f H (8)

[0067] Among them, N s is the number of welds; for a straight-line composite wall, N s =4; for T-shaped composite wall, N s =6; for a cross-shaped composite wall, N s =8; H is the vertical distance between the horizontal shear force point of the wall and the wall foundation; f tw Design strength for fillet welds;

[0068] For bolted or studded nodes, the bolt or stud size is 10 mm, and the number of bolts is calculated as follows:

[0069] N=max{N1,N2} (9)

[0070] N1={1.05(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ} / f vb (10)

[0071] Among them, N1 is the minimum weld size required for vertical shear resistance of the node;

[0072] N2 is the minimum number of bolts obtained based on the test structure. For the straight-shaped composite wall, N2 = 24; for the T-shaped and cross-shaped composite walls, N2 = 48;

[0073] f vb is the design strength of the bolt or stud.

[0074] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A modular design method based on CS-FC-SB combined wall, characterized by: The CS-FC-SB wall comprises a foamed concrete prefabricated wall with a cold-formed steel frame, an end column, an outer ecological straw board and a connection node. The prefabricated wall comprises a square cold-formed steel frame (1) for welding and assembly, an embedded vertical cold-formed steel (2) for fixing the straw board, a vertical tie bar (3) for preventing the straw board from expanding outward, and an inner foamed concrete (4). The end column is a steel section or a steel tube concrete column. The end column is connected to the steel frame of the foamed concrete prefabricated wall by reserved bolts, studs or welding. The foamed concrete prefabricated walls I, II, III and IV with cold-formed steel frames can be connected in an angle, T-shaped or cross-shaped manner.

2. The design method of a CS-FC-SB combined wall based on modular design according to claim 1, characterized in that: The foamed concrete prefabricated wall with cold-formed steel frame, end column, and outer ecological straw board are designed separately. After the above module designs are completed, only the connection nodes between the end column and the foamed concrete prefabricated wall need to be designed during assembly.

3. The design method of a CS-FC-SB combined wall based on modular design according to claim 1, characterized in that: The design of the foamed concrete prefabricated wall with cold-formed steel frame is divided into compressive bearing capacity design and shear bearing capacity design. The compressive bearing capacity design is designed using formula (1), and the shear bearing capacity design value is designed using formula (2). N c =0.2ζf c bh (1) Among them, N c is the vertical compressive bearing capacity; ζ is the correction factor for compressive bearing capacity of embedded vertical cold-formed steel considering the constraint effect of straw board. According to the test and finite element simulation results, the correction factor is taken as 1.05 (E s A s / (E c bh)); E s is the elastic modulus of the embedded vertical cold-formed steel; A s is the cross-sectional area of ​​the embedded vertical cold-formed steel; E c is the compressive elastic modulus of foam concrete; f c is the compressive strength of foam concrete prism, unit: MPa; h is the height of the wall section; b is the width of the wall section; V wh =(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ (2) Among them, V wh Horizontal shear bearing capacity; λ1 is the correction coefficient considering the contribution of straw board to shear resistance, and f yh A sh / (0.077f c hb+0.26N c ); λ2 is the correction coefficient considering the contribution of straw board to shear resistance, and f yv A sv / (0.077f c hb+0.26N c ); f vh With f yv are the yield strength of straw board and vertical cold-formed steel, respectively; A sh is the cross-sectional area of ​​the horizontal tie rod, and the horizontal direction is the fiber of the straw board. Based on the fact that the horizontal reinforcement of the reinforced concrete shear wall accounts for 75% of the total, the straw board covered on the wall is cut off at the post-casting belt, and the height is h b , the effect is taken as 75%×(hh b ) / h; A sv is the cross-sectional area of ​​the vertical tie rod, considering only the 0.8l in the center of the wall w Vertical cold-formed steel within the range; θ is the maximum allowable displacement angle of the wall. According to the test and finite element results, the value is taken as 1 / 100.

4. A modular design method based on CS-FC-SB combined wall according to claim 1, characterized in that: The thickness of the outer ecological straw board is selected and calculated using formulas (3) and (4). The finite element method is used to discretize and calculate the formulas, and the design is carried out based on the maximum stress value under the allowable displacement angle. Among them, u is the horizontal displacement and v is the vertical displacement; λ=E, E is the elastic modulus of the ecological straw board; μ is the Poisson's ratio of the ecological straw board; When the finite element method is used for calculation and discretization formula (3), the bottom boundary is taken as rigid connection, the plate thickness is 1, the top forced displacement is 0.01H, and the maximum strain is σ max , the design thickness d of the ecological board meets: d>f vh / s max (4) 5. The design method of a CS-FC-SB combined wall based on modular design according to claim 1, characterized in that: After the above connection form design is completed, the connection node becomes a weak point. According to the adopted node form, the corresponding design method is carried out. The calculation formula is shown in formulas (5) and (9): For welded joints, the weld leg size h f Take 4mm or 5mm, and the total length of the weld is calculated as follows <h2 style=";text-align:left;direction:ltr">l<h2 style=";text-align:left;direction:ltr"> weld <h2 style=";text-align:left;direction:ltr"> =max{min(l1,l2),l3} (5) l1={1.05(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ} / f tw h f (6) l2=0.8NsH (7) <h2 style=";text-align:left;direction:ltr">l3 = 60h<h2 style=";text-align:left;direction:ltr"> f <h2 style=";text-align:left;direction:ltr"> H (8) Among them, N s is the number of welds; for a straight-line composite wall, N s =4; for T-shaped composite wall, N s =6; for a cross-shaped composite wall, N s =8; H is the vertical distance between the horizontal shear force point of the wall and the wall foundation; f tw Design strength for fillet welds; For bolted or studded nodes, the bolt or stud size is 10 mm, and the number of bolts is calculated as follows: N=max{N1,N2} (9) N1={1.05(0.95+0.07λ1+0.025λ2)(0.077f c hb+0.26N c )cosθ} / f vb (10) Among them, N1 is the minimum weld size required for vertical shear resistance of the node; N2 is the minimum number of bolts obtained based on the test structure. For the straight-shaped composite wall, N2 = 24; for the T-shaped and cross-shaped composite walls, N2 = 48; f vb is the design strength of the bolt or stud.

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