Design method of conversion thick plate

Abstract

The invention discloses a design method of a conversion thick plate, relates to the technical field of constructional engineering, and aims at improving the section punching and shearing checking calculation method of the conversion thick plate by taking the compressive strength and the shear bearing capacity of concrete in a multi-axis compression state as a basis and taking the shear span ratio as a reference index. And improving a plate strip division method, and calculating the internal force by adopting a method considering a floor bidirectional bending moment and torque combination effect. Compared with a conventional technology, the potential that the shear bearing capacity of concrete is improved under the multi-axis compression state is fully excavated, the thickness of the conversion plate is optimized, and the thickness of the conversion plate can be optimized by 50% under the extreme condition; according to the method, the plate and strip division basis is clearer and more reasonable, deformation control and reinforcement construction requirements are supplemented, and the design result is safer.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and specifically to a design method for a transfer thick plate. Background Technique

[0002] The thick plate transfer structure has been applied since the 1970s. In China, due to insufficient research, the restrictions on thick plate transfer are relatively strict, which affects its popularization and use.

[0003] Currently, the biggest problem in the design of the transfer plate is that the plate thickness is too large, resulting in the concentration of the mass of the transfer layer, which is not conducive to the seismic resistance of the structure; the reinforcement design of the transfer plate follows the structure of the transfer beam, resulting in a complex structure and a large increase in the amount of materials used. The favorable conditions of the spatial force of the thick plate are not fully utilized, and the advantages of simple structure and convenient construction of the plate type transfer structure cannot be reflected. Summary of the Invention

[0004] The purpose of the present invention is to provide a design method for a transfer thick plate in order to solve the existing problems.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A design method for a transfer thick plate, including: S1: Estimation of the thickness of the transfer plate. The cross-sectional height of the transfer thick plate can initially be taken as 0.2 - 0.3 times the clear span of the short side of the floor slab. S2: Adopt the elastic design method, and calculate and analyze the internal force and deformation distribution of the transfer plate through a three-dimensional space model. S3: Check the allowable value of the vertical deformation of the transfer plate, and the suitability of the cross-sections for bending resistance, shear resistance, and punching shear resistance. S4: After the plate thickness is determined, the plate strips can be divided according to the finite element analysis results for design. The plate strips are divided into middle plate strips of columns, edge plate strips of columns, and middle plate strips of spans according to the relative position relationship with the column supports, and the internal forces of the plate strips are calculated respectively. S5: Substitute the plate strips into rectangular beams for reinforcement calculation. S6: Draw the reinforcement drawing of the transfer plate and check the construction requirements.

[0006] As a further scheme of the present invention: The transfer thick plate is to design a thick floor slab for a certain floor in the building structure, which is used to support the vertical members that cannot be directly landed above it and transfer the relevant loads to the vertical members and the foundation below it.

[0007] As a further scheme of the present invention: The span-thickness ratio of the transfer thick plate is not greater than 5, and the span-thickness ratio is the ratio of the clear span of the short side of the floor slab to the thickness of the floor slab.

[0008] As a further scheme of the present invention: In the three-dimensional space model, the transfer plate should adopt three-dimensional shell elements that can consider the transverse shear deformation.

[0009] As a further solution of the present invention: the allowable value of the vertical deformation of the conversion slab should not exceed 1 / 800 of the calculated span of the long side of the floor slab, and the influence of the support compression deformation should be deducted in the deformation calculation.

[0010] As a further solution of the present invention: the calculated span is l 0, and its calculated value is l n + min(0.5 S w , 0.5 h s ), where S w is the width of the support column or wall, h s is the thickness of the conversion slab.

[0011] As a further solution of the present invention: when estimating the thickness of the conversion slab, the reinforcement ratio of the longitudinal flexural reinforcement ρ s should not be greater than 1%. When estimating the thickness of the conversion slab, when the shear span ratio λ of the calculated section is less than 2.5, the shear resistance of the section should be checked; when the shear span ratio λ of the calculated section is greater than 2.5, the punching shear resistance of the section should be checked.

[0012] As a further solution of the present invention: the middle strip of the column refers to the strip-shaped area with the same width as the side length of the column section along the center line of the column. The side strip of the column refers to the strip-shaped area with a certain width distributed on one side of the edge column and both sides of the middle column, taking the larger value of 1 m or half of the slab thickness. The middle strip of the span is the strip-shaped area located between the side strips of the column.

[0013] As a further solution of the present invention: the internal force of the strip is the design value of the bending moment after comprehensively considering the combined effect of the two-way bending moment and torque of the floor slab, and is the design basis for the bending moment reinforcement of the thick slab section.

[0014] As a further solution of the present invention: the width of the rectangular beam is equal to the width of the slab strip, and the height is equal to the thickness of the slab. The stirrups of the rectangular beam can adopt stirrups As a further solution of the present invention: the design internal force of the middle strip of the column can be taken from the edge of the column or considering the influence of the rigid zone, so as to achieve the effect of peak reduction. The reinforcement of the middle strip of the column and the side strip of the column both adopt the envelope result of the two. The reinforcement of the middle strip of the span can directly adopt the envelope result of the internal force of each strip of the middle of the span for reinforcement, or can be reinforced separately according to the calculation results of the internal force of each strip. Among them, the width range of the peak moment reinforcement of the strip should not be less than the thickness of the slab; the bending moment calculation of the strip should comprehensively consider the combined effect of the two-way bending moment and torque of the floor slab.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The advantages of the present invention are as follows: It takes into account that the compressive strength and shear bearing capacity of the concrete between the shear wall supported by the conversion slab and the column support are increased under triaxial or biaxial compression. Taking the shear span ratio of the calculated section as the control condition, it exploits the potential of the shear bearing capacity of the concrete under different compressive states, thereby realizing the optimization of the thickness of the conversion slab. It solves the problem that the conventional design does not distinguish the stress state of the concrete and uses a unified standard for punching shear check, resulting in an overly large thickness of the conversion slab. Compared with the conventional technology, the thickness of the conversion slab can be optimized by 50% under extreme conditions.

[0016] 2. Another advantage of the present invention is that it refines the slab strip division rules and uses the design bending moment of the slab strip. It splits the "column strip" in the conventional technology into the "column center strip" and the "column edge strip", and conducts envelope design; the width of the "mid-span strip" is limited to not exceed the slab thickness. Compared with the conventional technology, the basis for slab strip division is clearer and more reasonable; the internal forces are calculated by using a method that considers the combined effect of the two-way bending moment and torque of the floor slab, and the calculation of the structural internal forces is more comprehensive, and the completed design result is safer.

[0017] 3. The technology of the present invention can effectively reduce the thickness of the conversion slab and the material consumption, reduce the construction difficulty of the joints, and the comprehensive benefits are obvious.

[0018] 4. In the present invention, the conversion slab structure reduces the constraint on the layout of the upper structure, helps to improve the product quality, and has a broad prospect of popularization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the conversion structure in a design method of a thick conversion slab according to the present invention; Figure 2 is a schematic diagram of the slab strip division method in a design method of a thick conversion slab according to the present invention; Figure 3 is a design flow chart of a design method of a thick conversion slab according to the present invention; Figure 4 is a schematic diagram of the unit stress in a design method of a thick conversion slab according to the present invention.

[0020] In the figure: 1. Upper structure; 2. Thick conversion slab; 3. Conversion column; 21. Column center strip; 22. Column edge strip; 23. Mid-span strip. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The embodiments of the present invention will be described below according to its overall structure.

[0023] Referring to Figures 1 to 3 , in the embodiments of the present invention: Embodiment 1 A method for designing a transfer thick plate includes: S1: Estimating the thickness of the transfer plate. The cross-sectional height of the transfer thick plate can initially be taken as 0.2 - 0.3 times the clear span of the short side of the floor slab; S2: Adopting an elastic design method to calculate and analyze the internal forces and deformation distributions of the transfer plate through a three-dimensional space model; S3: Checking the allowable value of the vertical deformation of the transfer plate and the suitability of the cross-sections for bending resistance, shear resistance, and punching shear resistance; S4: After determining the plate thickness, the plate strip can be divided according to the finite element analysis results for design. The plate strip is divided into a column center plate strip, a column edge plate strip, and a mid-span plate strip according to the relative positional relationship with the column support, and the internal forces of the plate strip are calculated respectively; S5: Equivalent the plate strip into a rectangular beam for reinforcement calculation; S6: Drawing the reinforcement drawing of the transfer plate and checking the construction requirements.

[0024] The transfer thick slab is designed by making a certain floor slab in the building structure into a thick floor slab to support the vertical members that cannot be directly landed on its upper part and transfer the relevant loads to the vertical members and foundation below it; the span-thickness ratio of the transfer thick slab is not greater than 5, and the span-thickness ratio is the ratio of the clear span of the short side of the floor slab to the thickness of the floor slab; in the three-dimensional space model, the transfer slab should adopt a three-dimensional shell element that can consider the transverse shear deformation; the allowable value of the vertical deformation of the transfer slab should not exceed 1 / 800 of the calculated span of the long side of the floor slab, and the influence of the support compression deformation should be deducted in the deformation calculation; the calculated span l 0, and its calculated value is l n + min(0.5 S w , 0.5 h s ), where S w is the width of the support column or wall, h s is the thickness of the transfer slab; when estimating the thickness of the transfer slab, the reinforcement ratio of the longitudinal flexural reinforcement ρ s should not be greater than 1%. When estimating the thickness of the transfer slab, when the shear span ratio λ of the calculated section is less than 2.5, the shear resistance of the section is checked; when the shear span ratio λ of the calculated section is greater than 2.5, the punching shear resistance of the section is checked; the middle strip of the column refers to the strip-shaped area with the same width as the side length of the column section along the center line of the column, the side strip of the column refers to the strip-shaped area with a certain width distributed on one side of the edge column and both sides of the middle column, taking the larger value of 1m or half of the slab thickness, and the middle strip of the span is the strip-shaped area located between the side strips of the column; the internal force of the strip is the design value of the bending moment after comprehensively considering the combined effect of the two-way bending moment and torque of the floor slab, and is the design basis for the bending moment reinforcement of the thick slab section; the width of the rectangular beam is equal to the width of the slab strip, the height is equal to the slab thickness, and the stirrups of the rectangular beam can adopt stirrups.

[0025] Example Two The Wood-Hammer rule states that if the moment per unit width of the strip in the finite element analysis is m xx , m yy and m xy , and the moment value is taken as an algebraic value, the reinforcement of the floor slab should be arranged along the x direction and y direction respectively to resist the ultimate moment y per unit width around the x direction and M x and M y , specifically as follows: For the bottom reinforcement, it should generally be calculated according to the following formula: If the calculated , or , then it shall be calculated according to the following formula: If , let , then If , let , then If there still exists or , it indicates that the bottom slab in the corresponding direction does not need to be configured with flexural reinforcement according to the calculation.

[0026] For the top reinforcement, it shall generally be calculated according to the following formula: If the calculated or , then it shall be calculated according to the following formula: If , let , then If , let , then If there still exists or , it indicates that the top slab in the corresponding direction does not need to be configured with flexural reinforcement according to the calculation.

[0027] Embodiment III Use a three-dimensional shell element calculation software that can consider transverse shear deformation to check the deformation, flexure, shear, and punching shear sections of the transfer slab: Under the action of the quasi-permanent combination of loads, the influence of the support deformation shall be deducted from the calculation of the vertical maximum deformation of the transfer slab, and the relative deformation calculated according to the length of the larger span shall not be greater than 1 / 800; the reinforcement ratio of the flexural longitudinal reinforcement of the transfer slab shall not be greater than 1.0%; the maximum principal shear stress obtained from the finite element stress analysis shall not exceed 0.25 ( is the design value of the axial compressive strength of concrete); when the shear span ratio of the calculated section is greater than 2.5, the punching shear check of the column or shear wall on the transfer slab shall be carried out, and the average shear stress of the calculated section shall not be greater than 1.2 ( (which is the design value of the axial tensile strength of concrete); according to the finite element analysis results, the slab is divided into column strip, column-edge strip and middle strip; the calculation of the strip moment adopts a calculation method that comprehensively considers the combined effect of the two-way moment and torque of the floor slab; according to the calculation results of the strip internal forces, the flexural and shear reinforcement calculations of the cross-section are carried out respectively and the reinforcement drawing is drawn to check the reinforcement details. When designing the transfer slab according to this method, the mechanical characteristics of concrete under multi-directional stress are fully considered and rationally designed. In terms of flexural design, the combined effect of the two-way moment and torque of the floor slab is comprehensively considered in the design of the strip, which is safer than the conventional strip design method. In terms of shear punching design, the influence of the shear span ratio is incorporated into the design, and the mechanical concept is clearer than the conventional design method, which can effectively reduce the thickness of the transfer slab. The introduction of the column-edge strip in the strip division and the refined division requirements for the middle strip make it safer and more economical than the conventional design.

[0028] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A thick plate conversion design method, characterized in that, Including: S1: Estimate the thickness of the transfer slab. The initial value of the cross-sectional height of the thick transfer slab can be taken as 0.2 - 0.3 times the clear span of the short side of the floor slab. S2: Adopt the elastic design method, and calculate and analyze the internal force and deformation distribution of the transfer slab through a three-dimensional space model. S3: Check the allowable value of the vertical deformation of the transfer slab, and the suitability of the cross-sections for bending resistance, shear resistance, and punching shear resistance. After determining the slab thickness, the slab strips can be divided according to the finite element analysis results for design. The slab strips are divided into middle strip along the column, edge strip along the column, and middle strip between columns according to their relative positions to the column supports, and the internal forces of the slab strips are calculated respectively. S5: Equivalent the slab strips to rectangular beams for reinforcement calculation. S6: Draw the reinforcement drawing of the transfer slab and check the construction requirements.

2. The design method of a conversion thick plate according to claim 1, characterized in that, The thick transfer slab refers to designing a certain floor slab in the building structure as a thick floor slab to support the vertical members that cannot directly land on the upper part, and transfer the relevant loads to the vertical members and foundation in the lower part.

3. A method for designing a conversion thick plate according to claim 1, characterized in that, The span-thickness ratio of the thick transfer slab is not greater than 5, and the span-thickness ratio is the ratio of the clear span of the short side of the floor slab to the floor slab thickness.

4. A method for designing a conversion thick plate according to claim 1, characterized in that, In the three-dimensional space model, the transfer slab should adopt three-dimensional shell elements that can consider the transverse shear deformation.

5. A method for designing a conversion thick plate according to claim 1, characterized in that, The allowable value of the vertical deformation of the transfer slab should not exceed 1 / 800 of the calculated span of the long side of the floor slab, and the influence of the support compression deformation should be deducted in the deformation calculation.

6. The design method of a conversion thick plate according to claim 5, characterized in that, The calculated span is l 0, and its calculated value is l n + min(0.5 S w , 0.5 h s ), where S w is the width of the support column or wall, h s is the thickness of the transfer slab.

7. A method for designing a converted thick plate according to claim 1, characterized in that The reinforcement ratio of longitudinal flexural reinforcement when estimating the thickness of the conversion slab ρ s should not be greater than 1%. When estimating the thickness of the conversion slab, when the shear span ratio of the calculated section λ is less than 2.5, the shear resistance of the section shall be checked When calculating the section shear-span ratio λ When it is greater than 2.5, the punching shear check of the section shall be carried out.

8. A method for designing a converted thick plate according to claim 1, characterized in that, The middle strip along the column refers to the strip-shaped area with the same width as the column section side length along the column center line. The edge strip along the column refers to the strip-shaped area with a certain width distributed on one side of the edge column and both sides of the middle column, taking the larger value of 1m or half of the slab thickness. The middle strip between columns is the strip-shaped area located between the edge strips along the column.

9. A method for designing a conversion thick plate according to claim 1, characterized in that, The internal force of the slab strip is the design value of the bending moment after comprehensively considering the combined effect of the two-way bending moment and torque of the floor slab, and is the design basis for the moment reinforcement of the thick slab section.

10. A method for designing a converted thick plate according to claim 1, characterized in that, The width of the rectangular beam is equal to the slab strip width, and the height is equal to the slab thickness. The stirrups of the rectangular beam can adopt stirrup ties.

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