Non-equivalent cast-in-place seismic design method for all-dry bolted shear wall structure

Abstract

The application discloses a kind of full dry type bolt connection shear wall structure "non-equivalent cast-in-place" seismic design method, comprising: by analyzing the force transmission mechanism of the concentrated position full dry type bolt connection shear wall structure system, the calculation method of the total base shear and story shear of the structure system is determined, the distribution of each floor story shear on each axis shear wall is determined, and the distribution of horizontal shear between each wallboard of the same axis is determined;Determine the simplified mechanical model of prefabricated bolt connection shear wall plate, determine the modeling method of the full dry type bolt connection shear wall structure system, determine the bearing capacity checking method of bolt connection joint, determine the bearing capacity checking method of the horizontal joint and vertical joint of the concentrated position full dry type bolt connection shear wall structure system, can solve the problem that the lateral stiffness caused by joint of the concentrated position full dry type bolt connection shear wall structure system is not clear and the difficulty of structural internal force analysis caused thereby, and can carry out seismic design on the full dry type bolt connection shear wall structure system.

Description

Technical Field

[0001] This invention relates to the field of seismic resistance technology for prefabricated building structures, and in particular to a seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place". Background Technology

[0002] Prefabricated buildings have become an important direction for the transformation of my country's construction industry due to their advantages such as easy quality assurance, fast construction speed, and green, low-carbon and environmentally friendly characteristics. Prefabricated concrete structures are one of the most basic earthquake-resistant prefabricated structural systems. They have advantages such as shortening the construction period, reducing the impact on the surrounding environment, saving energy, and easy quality assurance of components. They can effectively solve the problems of poor construction quality, lack of earthquake-resistant design, and non-standard production methods in low-rise and multi-story residential buildings in rural areas, and are suitable for current village and town construction.

[0003] Based on construction methods, prefabricated concrete structure systems are divided into prefabricated monolithic concrete structure systems and monolithic prefabricated concrete structure systems (also known as "fully prefabricated concrete structure systems"). Prefabricated monolithic concrete structures are prefabricated concrete components connected by reliable connection methods, forming a unified structure with on-site cast-in-place concrete and cement-based grouting. The connection method is wet connection, and the design method is "equivalent to cast-in-place." The premise of the "equivalent to cast-in-place" design method is that the reinforcing bars in adjacent prefabricated components can be reliably connected, such as using sleeve grouting connections, grout-anchored lap connections, or lap connections of reinforcing bars in post-cast strips. This allows the prefabricated concrete structure to basically achieve or approach the mechanical properties (including load-bearing capacity, stiffness, and ductility) of the cast-in-place concrete structure, meeting the requirements for building structural safety. The disadvantage of prefabricated monolithic concrete structure systems is the need for wet work on-site, which reduces construction efficiency and cannot fully realize the advantages of rapid construction of prefabricated buildings.

[0004] This research team invented a concentrated-part fully dry bolted shear wall structure, belonging to the fully prefabricated concrete structure system (see authorized invention patent CN110080418A). This patented concentrated-part fully dry bolted shear wall structure includes prefabricated foundations, prefabricated bolted shear wall panels, and prefabricated reinforced concrete floor slabs. All prefabricated components are connected by bolts, eliminating wet work on site. Its advantages include ease of disassembly, repair, reusability, and facilitates the structure's detachable and rapid post-earthquake repair capabilities. In this concentrated-part fully dry bolted shear wall structure system, both horizontal and vertical joints are connected by bolted steel plates. Under seismic loading, the prefabricated bolted shear wall panels gradually open at the horizontal joints, causing wall rotation and slippage along the joints. Therefore, compared to cast-in-place wall panels, the lateral stiffness of the prefabricated bolted shear wall panels is significantly reduced, failing to achieve the structural effect of "equivalent to cast-in-place," and thus the design theory of prefabricated concrete structures based on "equivalent to cast-in-place" cannot be applied. In response to the unique stress mechanism of this type of structure, this invention proposes a seismic design method for concentrated, fully dry bolted shear walls that is consistent with existing seismic design principles in my country, which is "not equivalent to cast-in-place". This method contributes to the promotion of this structural system and the development of prefabricated buildings. Summary of the Invention

[0005] This invention provides a seismic design method for fully dry bolted shear wall structures that is "not equivalent to cast-in-place". This method addresses the problem that, in the prior art, the lateral stiffness of precast bolted shear wall panels is significantly reduced compared to cast-in-place wall panels, failing to achieve the structural effect of "equivalent to cast-in-place" and thus preventing the application of prefabricated concrete structure design theories based on "equivalent to cast-in-place".

[0006] The technical solution adopted in this invention is: to provide a seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place", including:

[0007] Step 1: Use the base shear method for seismic calculation, taking only one degree of freedom for each floor, to determine the total base shear and story shear of the fully dry bolted shear wall structure system at the concentrated location;

[0008] Step 2: Determine the distribution of floor shear force on each axis shear wall and calculate the horizontal shear force on each axis wall panel; when using cast-in-place floor slabs or precast monolithic concrete floor slabs, the floor shear force of the structure is distributed according to the equivalent stiffness of the lateral force resisting members, that is, according to the lateral stiffness of the precast bolt-connected shear wall panels; when using precast floor slabs, the distribution is based on the proportion of the subordinate area of ​​each axis wall panel;

[0009] Step 3: Determine the distribution of horizontal shear force among the wall panels on the same axis. The distribution of horizontal shear force among the wall panels does not consider the constraint effect of vertical connection nodes on the wall panels, and follows the principle of distribution according to lateral stiffness.

[0010] Step 4: Verify the bearing capacity of the bolted connection node based on the calculation results of Steps 1-3, including the tensile bearing capacity and shear bearing capacity of the bolted connection node;

[0011] Step 5: Based on the calculation results of Steps 1-3, perform load-bearing capacity verification at horizontal and vertical joints, including verification of the flexural capacity of horizontal joints, verification of the shear capacity of horizontal joints, and verification of the shear capacity of vertical joints.

[0012] Step 6: Based on the verification results of Step 4 and Step 5, conduct the first stage seismic design analysis of the concentrated part of the fully dry bolted shear wall structure, and evaluate the structural safety performance and optimize the node layout.

[0013] Furthermore, in step 2, the method for calculating the lateral stiffness of the prefabricated bolt-connected shear wall panel includes:

[0014] Treating precast bolt-connected shear wall panels as cast-in-place walls, the initial stiffness decreases due to the presence of joints. Therefore, a lateral stiffness reduction factor for precast bolt-connected shear wall panels is introduced.

[0015] Define the lateral stiffness reduction factor γ for precast bolted shear wall panels. Based on the results of parameter analysis, a simplified calculation formula for the lateral stiffness reduction factor of precast bolted shear wall panels is fitted and regressed, incorporating four parameters: the steel ratio of the bolted nodes, the height-to-width ratio of the wall, the axial compression ratio, and the relative position of the nodes. That is:

[0016] γ=K / K0

[0017]

[0018] ω = As / bt × 100%

[0019] β=H / b

[0020] ξa=as / b

[0021] α=N / fcbt

[0022] In the formula, K is the lateral stiffness of the precast bolted shear wall panel, K0 is the lateral stiffness of the cast-in-place wall of the same size, ω is the steel ratio of the bolted joint, β is the height-to-width ratio of the wall panel, ξa is the relative position of the joint, α is the axial compression ratio, fc is the design value of the axial compressive strength of concrete, H, b, and t are the height, width, and thickness of the precast bolted shear wall panel, respectively, As is the cross-sectional area of ​​the connecting steel plate, as is the distance from the bolted joint to the edge of the wall, and N is the axial force.

[0023] Furthermore, in step 2, for a single precast bolt-connected shear wall panel, its lateral stiffness is calculated based on the lateral stiffness of a cast-in-place wall of the same size and multiplied by a lateral stiffness reduction factor. However, for multiple wall panels spliced ​​together along the same axis through bolt-connected nodes, the constraint effect of vertical nodes on the wall panels is ignored, and its overall stiffness is equal to the sum of the stiffnesses of each wall panel, i.e.:

[0024] K 总 =γ1K1+γ2K2+…+γ n K n .

[0025] Furthermore, in step 4, for bolted joints, there are three failure modes under tensile stress: tensile yielding failure of the connecting steel plate, shear failure of the high-strength bolts, and shear-punching failure of the concrete surrounding the bolt holes in the tension zone. The bearing capacity calculation formula for each failure mode is as follows:

[0026] N p =n p f p A p

[0027]

[0028] F l =0.5f t ημ m h0+0.8f yv A svu +f y A sl

[0029] N j =min(N) p N v,b ,F l )

[0030] Where, N p N v,b F l N j These are the tensile bearing capacity of the steel plate, the shear bearing capacity of the bolt, the punching shear bearing capacity of the bolt hole wall, and the tensile bearing capacity of the bolted connection joint; f p , f t f yv f y These are the design values ​​for the tensile strength of steel plates, the shear strength of high-strength bolts, the axial tensile strength of concrete, and the tensile strength of stirrups and reinforcing bars; n p n b n v These represent the number of steel plates, bolts, and shear surfaces of the bolts in the connection node, respectively; A p Asvu A sl These represent the tensile cross-sectional area of ​​the connecting steel plate, the total stirrups intersecting the oblique section of the 45° punching failure cone and passing through the top surface of the punched body, and the cross-sectional area of ​​the vertical reinforcing bars; d is the diameter of the screw rod; μ m h0 is the perimeter of the calculated section; h0 is the effective height of the calculated inclined section.

[0031] Furthermore, in step 4, when the bolted connection node fails under shear, there are two failure modes: shear failure of the connecting steel plate and shear failure of the high-strength bolt. The bearing capacity calculation formula for each failure mode is as follows:

[0032] V p =n p f v A j

[0033] V j =min(V p N v,b )

[0034] Among them, V p V j These represent the shear capacity of the steel plate and the shear capacity of the bolted connection joint, respectively; fv is the shear strength of the steel plate; A j This represents the shear cross-sectional area of ​​the steel plate.

[0035] Furthermore, step 5 specifically includes the following sub-steps:

[0036] When the horizontal joint section still satisfies the plane section assumption, under horizontal seismic action, the horizontal joint of the wall bears axial force, shear force and bending moment. When bending failure occurs, the end concrete is under pressure and the joint is under tensile stress. The typical failure mode is that the concrete in the compression zone collapses and the outermost tension joint fails. Based on the vertical force balance and bending moment balance of the section under the ultimate state, the bending bearing capacity of the horizontal joint of the precast bolted shear wall panel is verified.

[0037] M0 = N j1 (l j1 -x / 2)+N j2 (l j2 -x / 2)+N(l / 2-x / 2)

[0038] α1f c b w x = N + N j1 +N j2

[0039]

[0040] In the formula, N jiLet f be the nodal tension at the i-th connection node, x be the height of the concrete compression zone, and f be the nodal tension. c b is the design value of the axial compressive strength of concrete. w The equivalent thickness of the precast bolt-connected shear wall panel is given by α1 and β1, which are concrete specification coefficients. When the concrete strength grade does not exceed C50, they are taken as 1.0 and 0.8 respectively.

[0041] Calculate the relative limiting compression zone height ξ when tension joint failure and compression zone concrete occur simultaneously. b :

[0042]

[0043]

[0044] We first assume that the wall panel fails at a tension joint. In this case, N j1 =N j N j To determine the design value of the tensile bearing capacity of the bolted connection joint, calculate the height x and N of the compression zone. j2 And the relative height of the pressure zone ξ:

[0045]

[0046] Compare ξ with ξ b If ξ≤ξ b If the above assumptions are correct, the tension node will fail first, and the flexural capacity M of the horizontal joint can be calculated according to the moment equilibrium law; otherwise, ξ>ξ b The concrete in the end compression zone fails before the tension joint. At this time, N j1 <N j The actual tensile force It can be obtained from the following formula:

[0047]

[0048] ε p =N j / (EA p )

[0049] Will Substituting into the above formula, we obtain the new height of the compression zone, x. * And the new horizontal joint flexural bearing capacity;

[0050] In the formula, E s ξ is the elastic modulus of steel; cu ξ represents the ultimate compressive strain of concrete under non-uniform compression. h The tensile strain caused by bolt joint slippage can be taken as the gap Δ between the bolt hole wall and the bolt. sThe distance h between the resultant point of the upper wall panel bolts and the resultant point of the lower wall panel bolts. j The ratio; ε p The tensile strain caused by the tensile force at the node when the boundary is breached;

[0051] The shear capacity V0 of the horizontal joint is provided by the shear capacity of the bolted connection node and the frictional force of the horizontal joint section:

[0052] V0 = nV j +μN

[0053] In the formula, n is the number of horizontal bolt connection nodes; μ is the friction coefficient between the upper and lower wall panels; N is the design value of the axial force perpendicular to the joint surface, which is positive for pressure and negative for tension.

[0054] Based on the horizontal shear force experienced by the precast bolt-connected shear wall panel, the shear capacity of the vertical joint is verified:

[0055]

[0056] V s ≤mV js

[0057] In the formula, coefficient 1.2 is an amplification factor considering the influence of other factors, V is the horizontal shear force of the wall panel; H and L are the height and width of the wall panel, respectively, and V js denoted as , where m represents the shear capacity of the vertical connection nodes, and m represents the number of vertical connection nodes.

[0058] Furthermore, the seismic effect analysis of the concentrated part of the fully dry bolted shear wall structure system is completed by constructing a simplified mechanical model of the prefabricated bolted shear wall panel structure, replacing the work in steps 1 to 3.

[0059] The beneficial effects of this invention are:

[0060] 1) This invention proposes a method for calculating the lateral stiffness of precast bolted shear wall panels, determines the calculation formula for the lateral stiffness reduction coefficient, and fully considers the influence of joints on the stiffness of precast bolted shear wall panels. This allows for a distinction in elastic stiffness characteristics between fully dry bolted shear wall structures in concentrated areas and traditional cast-in-place structures with the same wall panel size. This enables the new structure to use a suitable and accurate structural analysis model in the first stage of seismic design, solving problems such as unclear lateral stiffness caused by joints in fully dry bolted shear wall structures in concentrated areas and the resulting difficulties in structural internal force analysis.

[0061] 2) This invention proposes a method for calculating and distributing seismic forces in a concentrated dry bolted shear wall structure system. It clarifies the calculation methods for key mechanical parameters such as the tensile and shear bearing capacity of bolted joints, the flexural and shear bearing capacity of horizontal joints, and the shear bearing capacity of vertical joints. With this setup, conventional design software can be used to establish a calculation model for the concentrated dry bolted shear wall structure system. Only the internal force results required for the seismic analysis of the structure need to be extracted to carry out the first stage of seismic design analysis of the concentrated dry bolted shear wall structure, and to evaluate the structural safety performance and optimize the joint layout. Attached Figure Description

[0062] Figure 1 This is a rendering of a shear wall structure system with fully dry bolted connections in the concentrated area.

[0063] Figure 2 The diagram shows a prefabricated bolt-connected shear wall panel structure, derived from invention patent CN110080418A.

[0064] Figure 3(a) is a schematic diagram of the structure of the horizontal bolt connection node and the vertical bolt connection node.

[0065] Figure 3(b) is a structural schematic diagram of the bolted connection nodes of precast wall panel-precast floor slab and precast floor slab-precast floor slab.

[0066] Figure 4(a) is a schematic diagram of the structure of the L-shaped bolt connection node.

[0067] Figure 4(b) is a structural schematic diagram of a rectangular bolt connection node used to fix a horizontal seam.

[0068] Figure 4(c) is a structural schematic diagram of a rectangular bolt connection node used to fix vertical seams.

[0069] Figure 5 A schematic diagram illustrating the seismic design process for a shear wall structure system with fully dry bolted connections in concentrated areas.

[0070] Figure 6 A simplified diagram for calculating horizontal seismic forces on a structure.

[0071] Figure 7 This is a schematic diagram of the structure's lateral seismic resistance.

[0072] Figure 8(a) is a schematic diagram of the deformation mode (before deformation) of a horizontally bolted shear wall panel.

[0073] Figure 8(b) is a schematic diagram of the deformation mode (after deformation) of the horizontal bolt-connected shear wall panel.

[0074] Figure 9 This is a schematic diagram showing the distribution of horizontal shear force among the wall panels.

[0075] Figure 10(a) is a simplified model of a bolted shear wall panel (“elastic connection” model).

[0076] Figure 10(b) is a simplified model of a bolted shear wall panel (“stiffness reduction” model).

[0077] Figure 11 This is a schematic diagram of a prefabricated bolted shear wall panel.

[0078] Figure 12(a) is a simplified model diagram of the system (Model 1).

[0079] Figure 12(b) is a simplified model diagram of the system (Model 2).

[0080] Figure 13 This is a simplified diagram of the forces acting on a bolted connection node.

[0081] Figure 14 This is a schematic diagram of the failure modes of a bolted shear wall panel.

[0082] Figure 15 This is a simplified diagram of the stress on the horizontal joint section.

[0083] Figure 16 This is a flowchart for calculating the flexural bearing capacity of a horizontal joint.

[0084] Figure reference numerals: 1-Precast bolted shear wall panel; 2-Precast reinforced concrete floor slab; 3-Precast foundation; 4-Horizontal bolted connection node; 5-Vertical bolted connection node; 6-Precast wall panel-precast floor slab bolted connection node; 7-Precast floor slab-precast floor slab bolted connection node; 8-High-strength bolt; 9-Connecting steel plate; 10-Subordinate area; 11-Toe compression zone concrete; 12-Vertical reinforcement; 13-Anti-punching stirrup; 14-Compression zone concrete crushing; 15-Tensile failure of bolted connection node; 16-Bolt hole. Detailed Implementation

[0085] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in further detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0086] Based on the force transmission mechanism of bolted shear wall panels, this invention further proposes a "non-equivalent cast-in-place" seismic design method for concentrated, fully dry bolted shear wall structures that conforms to my country's seismic design principles. For example... Figure 1 As shown, all structural components are precast and connected using dry bolts. The precast components include precast foundations 3 and precast bolt-connected shear wall panels 1 (see...). Figure 2) and precast reinforced concrete floor slab 2. Among them, the precast bolt-connected shear wall panel is not only the main load-bearing and lateral force resisting component, but also the partition and enclosure component. Horizontal joint bolt connection node 4 and vertical joint bolt connection node 5, precast wall panel-precast floor slab bolt connection node 6 and precast floor slab-precast floor slab bolt connection node 7 are shown in Figures 3(a) and (b). By reserving bolt holes 16 in the precast components, 10.9S grade bearing high-strength bolts 8 and Q235-B connecting steel plates 9 (see Figures 4(a), (b), (c)) are used to splice between foundations, between wall panels and foundations, between wall panels and wall panels, between wall panels and floor slabs, and between floor slabs.

[0087] See Figure 5 The seismic design method for fully dry bolted shear wall structures that is "not equivalent to cast-in-place" proposed in this invention has the following specific steps:

[0088] Step 1: Conduct preliminary structural design. This includes: 1) Determining the structural layout based on the architectural design, i.e., the division of precast bolt-connected shear wall panels and the setting of partition walls; 2) Preliminarily determining the location of the connection nodes of precast components, the number of bolts, and the spacing of bolts based on the two connection nodes of each precast bolt-connected shear wall panel; 3) Preliminarily determining the reinforcement of precast concrete components (including wall panels, floor slabs, roof panels, etc.) according to the minimum reinforcement ratio required by the "Code for Design of Concrete Structures" (GB 50010-2010); 4) Preliminarily determining the material types of precast concrete components, connecting steel plates, bolts, and other components.

[0089] In this step, the structural design of the concentrated dry bolted shear wall structure system should follow the following three principles when designing the wall panels: 1) Arrange the prefabricated bolted shear wall panels in a reasonable and symmetrical manner to ensure uniform distribution of the overall structural stiffness; 2) The size of the prefabricated bolted shear wall panels should take into account the manufacturing process and transportation conditions; 3) The prefabricated bolted shear wall panels should be evenly and dispersed in the longitudinal and transverse directions, and the number of longitudinal and transverse wall panels should not differ too much.

[0090] Step 2: Seismic action and effect analysis to determine the horizontal shear force experienced by each wall panel under horizontal seismic action.

[0091] In some embodiments of the present invention, step 2 may specifically take the following two methods and their sub-steps:

[0092] Method 1: For shear wall structures with fully dry bolted connections in concentrated areas, a simplified theoretical calculation method can be used when analyzing the seismic action effect.

[0093] Step 2.1.1: Calculation of total base shear and story shear (see...) Figure 6For shear wall structures with concentrated dry bolt connections, shear deformation is dominant, and the mass and stiffness are generally evenly distributed along the height. Therefore, the base shear method can be used for seismic calculations. According to the "Code for Seismic Design of Buildings" (GB 50011-2010), when using the base shear method, only one degree of freedom can be taken for each floor. The standard value of the horizontal seismic action for each floor should be determined according to the following formula:

[0094] F EK =α1G eq

[0095]

[0096] △F n =δ n F EK

[0097] Considering that low-rise wall panel structures generally have high stiffness and small vibration periods, the horizontal seismic influence coefficient value is usually located in the rising segment or plateau segment of the seismic influence coefficient curve. Therefore, the horizontal seismic influence coefficient value α1 can be directly taken as α. max In the formula, F EK G represents the standard value of the total horizontal seismic force on the structure, α1 is the horizontal seismic influence coefficient corresponding to the fundamental natural period of the structure, and G... eq For the equivalent total gravity load of the structure, the representative value of the total gravity load should be taken for a single mass point, and 85% of the representative value of the total gravity load should be taken for multiple mass points. F i Let G be the standard value of the horizontal seismic action at mass point i. i G j H represents the representative values ​​of gravity load concentrated at mass points i and j, respectively. i H j δ represents the calculated heights of particles i and j, respectively. n Add a seismic action coefficient to the top, ΔF n Add horizontal seismic action to the top.

[0098] Step 2.1.2: Determine the distribution of shear force on each floor along each axis wall (see...). Figure 7 When using cast-in-place or prefabricated concrete floor slabs, the floor shear force of the structure should be distributed according to the equivalent stiffness of the lateral force resisting members, that is, according to the lateral stiffness of the bolted shear wall panels; when using precast floor slabs, it should be distributed according to a ratio of 10 to the tributary area of ​​the wall panels on each axis.

[0099] γ=K / K0

[0100]

[0101] ω=A s / bt×100%

[0102] β=H / b

[0103] ξ a =a s / b

[0104] α=N / f c bt

[0105] In the formula, γ is the reduction factor for the lateral stiffness of the precast bolted shear wall panel, K is the lateral stiffness of the precast bolted shear wall panel, K0 is the lateral stiffness of a cast-in-place wall of the same size, ω is the steel ratio of the bolted joint, β is the height-to-width ratio of the wall, and ξ... a The relative positions of the nodes, α is the axial compression ratio, and f c N is the design value of the axial compressive strength of concrete, and N is the axial force (see Figure 8(a) and (b)).

[0106] Step 2.1.3: Determine the distribution of horizontal shear force among the wall panels on the same axis (see...) Figure 9 When multiple wall panels are arranged along the same axis, the distribution of horizontal shear force among the wall panels does not consider the constraint effect of vertical connection nodes on the wall panels, and follows the principle of distribution according to lateral stiffness.

[0107] The horizontal shear force V on each wall panel i Calculate using the following formula:

[0108]

[0109] In the formula, K i Let V be the stiffness of the i-th wall panel (after considering stiffness reduction), and let V be the horizontal shear force experienced by the coaxial wall panels.

[0110] Step 2.1.4: Based on the calculated horizontal shear force V of each wall panel i Furthermore, the bending moment M borne by the wall panel can be calculated. i =V i H, the axial force N of a single wall panel can be determined based on the distribution of the load-bearing area. i Taking a single wall panel as an isolated body, considering the most unfavorable stress conditions, and knowing the axial force, bending moment, and horizontal shear force it experiences, the next stage of design is carried out.

[0111] Method 2: Use existing engineering design software for modeling and calculation.

[0112] Method 2 completes the seismic effect analysis of the concentrated part of the fully dry bolted shear wall structure system by constructing a simplified mechanical model of the prefabricated bolted shear wall panel structure, replacing the work of Method 1.

[0113] Step 2.2.1: To facilitate compatibility with commonly used engineering design software, this invention proposes a simplified mechanical model for prefabricated bolt-connected shear wall panels, as shown in Figures 10(a) and (b), and employs the following analysis method:

[0114] The first type is the "elastic connection" model, which simulates the mechanical behavior of bolted joints in horizontal seams by setting up elastic connections at the joints, as shown in Figure 10(a). A single tension-shear spring is set at the bolted joint of the horizontal seam, and its axial tensile stiffness is determined by the bolted steel plate and calculated using K. b =E s A s / l s The shear stiffness K of the spring Vb =GA s / b s , of which E s G and G are the elastic modulus and shear modulus of steel, respectively. The shear modulus of steel is calculated according to the formula G = E for isotropic materials. s / 2(1+v) is used to take values, where v is the Poisson's ratio of the steel, and A s l s b s They are respectively Figure 11 The diagram shows the cross-sectional area of ​​the connecting steel plate, the distance between the upper and lower bolt groups, and the width. It is assumed that the precast bolted shear wall panel has sufficient out-of-plane support, i.e., its out-of-plane deformation is not considered; therefore, the out-of-plane shear stiffness can be set to infinitely large. Simultaneously, considering that the wall panel ultimately fails due to the crushing of the concrete in the toe compression zone, a single compression-only spring is installed at the end of the wall panel, with a compressive stiffness K. c =E c A c / l c A c l c They are respectively Figure 11 The cross-sectional area and length of the concrete block 11 in the compression zone of the wall toe are shown. Since the rotational constraint of a single bolted connection node on the wall panel is very small, it can be regarded as a hinge in the analysis of the general elastic stage, that is, constraining the three translational degrees of freedom in the X, Y, and Z directions, and releasing the three rotational degrees of freedom.

[0115] The second type is the stiffness reduction model, as shown in Figure 10(b). The precast bolt-connected shear wall panel is regarded as a cast-in-place wall. However, considering the decrease in the initial lateral stiffness due to the presence of joints, a lateral stiffness reduction coefficient for the precast bolt-connected shear wall panel is introduced. Since the first stage of seismic design adopts the elastic method, the change of the wall panel stiffness with the action effect is not considered.

[0116] In structural design software such as PKPM and YJK, a structural model was established based on a concentrated dry-bolted shear wall structure system (see Figures 12(a) and (b)). This structural model differs from the traditional cast-in-place structural model and requires full consideration of the influence of joints on structural stiffness. The overall modeling of the concentrated dry-bolted shear wall structure system is described below:

[0117] 1) Precast bolted shear wall panels

[0118] When using the "elastic connection" wall panel unit model, precast bolted shear wall panels can be simulated using "plate elements." First, the wall panel is discretized into appropriately sized plate elements. Then, tension and shear springs are installed at the bolted connection nodes of the horizontal joints, and compression springs are installed at the wall toes at the ends of the horizontal joints. When using the "stiffness reduction" wall panel unit model, "wall elements" are used as in cast-in-place shear wall structures. Each precast bolted shear wall panel is a "wall element," and its lateral stiffness is considered with a lateral stiffness reduction factor. The first-floor wall panels are all fixed to the bottom, and the first-floor and second-floor wall panels share nodes, with the same boundary conditions as cast-in-place walls.

[0119] 2) Vertical seam

[0120] In actual engineering construction, a 20mm vertical gap is reserved to facilitate the assembly of wall panels. The modeling of the vertical gap also reserves a certain width based on the actual engineering conditions. When using the "elastic connection" wall panel unit model, since the panel unit is segmented, elastic connections can be set at the bolt nodes of the vertical gap. From the analyzed system's stress characteristics, under horizontal seismic action, there is a tendency for wall panels to shift relative to each other along the vertical gap direction. The transmission of horizontal forces between wall panels mainly relies on the vertical gap; therefore, the bolt nodes at the vertical gap have shear and tensile resistance in their plane. To simulate the connection effect of the bolt connection nodes at the vertical gap, a tension-shear spring is set at the vertical gap node, and its stiffness is calculated in the same way as the horizontal gap. When using the "stiffness reduction" wall panel unit model, the wall unit is treated as a whole, and elastic connections cannot be arranged at the vertical gap. Instead, connecting units can be added to the top of the wall panel unit. The area of ​​the connecting unit is the cross-sectional area of ​​the connecting steel plate, and the elastic modulus is consistent with that of the steel.

[0121] 3) Floor slab

[0122] Precast reinforced concrete floor slabs are constructed using "slab units". According to the actual project conditions, a certain width of gap is reserved between the wall panels and the floor slabs. Tension-shear elastic connections are set between floor slabs and between wall panels and floor slabs. The elastic connection positions correspond to the actual bolt connection node positions. The calculation method of its tension-shear spring stiffness is the same as that of the node at the horizontal joint.

[0123] When precast floor slabs are bolted together, sufficient in-plane stiffness can be ensured. If there are no large openings, a rigid floor slab assumption can be used in the overall system modeling to simplify the modeling and calculation process. However, since the actual connection method of the floor slab is to rest on the inner leaf wall panel and use bolt connection, its boundary constraints cannot be regarded as rigid connection. When the floor slab and wall panel share nodes, "slab end constraint" release is required, that is, release the three rotational degrees of freedom of these nodes, but retain the three translational degrees of freedom.

[0124] Step 2.2.2: After completing the overall system modeling of the concentrated dry bolted shear wall structure, input the actual load conditions and perform static analysis on the structure. When calculating the seismic effect, the modal decomposition method can be used. Check its natural period and mode shape, and evaluate the seismic performance indicators such as inter-story drift angle and displacement ratio. Analyze the internal force results of the structure, extract the internal forces of elastic connections and support reactions, and design the bolted connection nodes.

[0125] Step 3: Based on the known internal force results, design the bolted connection nodes, including verifying the tensile and shear bearing capacity of the bolted connection nodes, verifying the bending bearing capacity of the horizontal joints, verifying the shear bearing capacity of the horizontal joints, and verifying the shear bearing capacity of the vertical joints.

[0126] In some embodiments of the present invention, step 3 specifically includes the following sub-steps:

[0127] Step 3.1: Based on the most unfavorable combination of internal forces calculated using simplified theory or the most unfavorable internal force condition of the connection node extracted from the design software, determine the tensile and shear bearing capacity of the bolted connection node (see...). Figure 13 Verification is performed to determine whether the bolted connection meets the strength requirements. The tensile bearing capacity calculation method is as follows:

[0128] N p =n p f p A p

[0129]

[0130] F l =0.5f t ημ m h0+0.8f yv A svu +f y A sl

[0131] N j =min(N) p N v,b ,F l )

[0132] Where, N p N v,b F l N j These are the tensile bearing capacity of the steel plate, the shear bearing capacity of the bolt, the punching shear bearing capacity of the bolt hole wall, and the tensile bearing capacity of the bolted connection joint; f p , f t f yv f y These are the design values ​​for the tensile strength of steel plates, the shear strength of high-strength bolts, the axial tensile strength of concrete, and the tensile strength of stirrups and reinforcing bars; n p n b n v These represent the number of steel plates, bolts, and shear surfaces of the bolts in the connection node, respectively, and can all be taken as 2; A p A svu A sl These represent the tensile cross-sectional area of ​​the connecting steel plate, and the cross-sectional areas of all anti-punching stirrups 13 and vertical reinforcing bars 12 intersecting the oblique section of the 45° punching failure cone and passing through the top surface of the punching body; d is the diameter of the screw rod; μ m h0 is the perimeter of the calculated section; h0 is the effective height of the calculated inclined section.

[0133] The method for calculating the shear capacity of bolted joints is as follows:

[0134] V p =n p f v A j

[0135] V j =min(V p N v,b )

[0136] Among them, V p V j These are the shear bearing capacity of the steel plate and the shear bearing capacity of the bolted connection joint, respectively; f v For the shear strength of the steel plate, A j This represents the shear cross-sectional area of ​​the steel plate.

[0137] Step 3.2: Assuming the horizontal joint section still satisfies the plane section assumption, under horizontal seismic action, the horizontal joint of the wall bears axial force, shear force, and bending moment. When bending failure occurs, the end concrete is under compression, and the joint bears tensile stress. The typical failure mode is the crushing of the concrete in the compression zone 14 and the outermost bolted joint undergoing tensile failure 15. Figure 14 Based on the vertical force equilibrium and bending moment equilibrium of the section under the limit state (see...). Figure 15 ), and perform flexural bearing capacity verification of horizontal joints in precast bolted shear wall panels (see Figure 16 );

[0138] M0 = N j1 (l j1 -x / 2)+N j2 (l j2 -x / 2)+N(l / 2-x / 2)

[0139] α1f c b w x = N + N j1 +N j2

[0140]

[0141] In the formula, N ji Let f be the nodal tension at the i-th connection node, x be the height of the concrete compression zone, and f be the nodal tension. c b is the design value of the axial compressive strength of concrete. w α1 and β1 are the equivalent thickness of the wall panel, and the concrete specification coefficients are 1.0 and 0.8 respectively when the concrete strength grade does not exceed C50.

[0142] Calculate the relative limiting compression zone height ξ when tension joint failure and compression zone concrete occur simultaneously. b :

[0143]

[0144]

[0145] We first assume that the wall panel fails at a tension joint. In this case, N j1 =N j N j To determine the design value of the tensile bearing capacity of the bolted connection joint, calculate the height x and N of the compression zone. j2 And the relative height of the pressure zone ξ:

[0146]

[0147] Compare ξ with ξ b If ξ≤ξ b If the above assumption is correct, the tension node will fail first, and the flexural capacity M of the horizontal joint can be calculated according to the formula for verifying the flexural capacity of the horizontal joint of the precast bolted shear wall panel; otherwise, ξ>ξ b The concrete in the end compression zone fails before the tension joint. At this time, N j1 <N j The actual tensile force It can be obtained from the following formula:

[0148]

[0149] ε p =N j / (EA p )

[0150] Will Substituting into the above formula, we obtain the new height of the compression zone, x. * And the new horizontal joint flexural bearing capacity.

[0151] In the formula, ξ cu ξ represents the ultimate compressive strain of concrete under non-uniform compression, taken as 0.0033; h The tensile strain caused by bolt joint slippage can be taken as the gap Δ between the bolt hole wall and the bolt. s The distance h between the resultant point of the upper wall panel bolts and the resultant point of the lower wall panel bolts. j The ratio; ε p The tensile strain caused by the tension at the node when the boundary is breached.

[0152] Based on the most unfavorable internal force conditions of wall panels of various sizes calculated by simplified seismic design theory, or based on the axial force, shear force and bending moment of horizontal joints obtained by extracting the internal forces of each elastic connection from the design software and synthesizing them according to the equilibrium law, the failure mode of the wall panel is predicted to be either failure of the tension joint or crushing of the concrete in the compression zone, thereby determining whether it is safe.

[0153] Step 3.3: Calculation of the shear capacity of the horizontal joint. The shear capacity V of the horizontal joint. p The shear capacity of the bolted joint is provided by the shear capacity of the bolted connection node and the frictional force of the horizontal joint section. According to the "Technical Specification for Prefabricated Concrete Structures" JGJ 1-2014, the shear capacity V0 of the horizontal joint is calculated by the following formula:

[0154] V0 = nV j +μN

[0155] In the formula, n is the number of bolted joints in the horizontal seam, which is generally taken as 2; μ is the friction coefficient between the upper and lower wall panels. Since the horizontal joints of the precast wall panels are filled with grouting material instead of grouting, the static friction coefficient of the joint is low when it is under shear, so it is taken as 0.6; N is the design value of the axial force perpendicular to the joint surface. It is positive when under pressure and negative when under tension.

[0156] Step 3.4: Calculation of shear capacity of vertical joints. The shear force of vertical joints must meet the following requirements:

[0157] V s ≤mV js

[0158] In the formula, V js denoted as , where m represents the shear capacity of the vertical joint nodes, and m represents the number of vertical connection nodes.

[0159] Step 4: Based on the verification results of Step 3, conduct the first-stage seismic design analysis of the concentrated dry bolted shear wall structure, and evaluate the structural safety performance and optimize the node layout. The first stage refers to the seismic design of the elastic stage, while the second stage usually refers to the seismic design of the elastoplastic stage.

[0160] In one embodiment of the present invention, a specific example is provided as follows:

[0161] The demonstration project of a fully dry-bolted shear wall structure system in a concentrated area is located in a region with a seismic fortification intensity of 7 degrees, a basic design earthquake acceleration of 0.10g, and a design seismic group of Group III. The project is a two-story prefabricated wall panel structure with a total building area of ​​232.23m². 2 The first floor has a building area of ​​129.69m². 2 The first floor has a height of 3.95m; the second floor has a building area of ​​102.54m². 2 The floor height is 3.50m. The concrete and steel reinforcement materials used for the precast shear walls, precast floor slabs, and precast foundations are:

[0162] Precast bolted shear wall panels: C30 concrete is used, with HRB400 for horizontal and longitudinal reinforcement and HRB335 for stirrups. Width specifications are 1800mm, 3600mm, 4300mm and 4500mm. The thickness of the precast sandwich insulated wall panel is 200mm. The inner and outer wall panels in the precast wall panel are load-bearing wall panels with a thickness of 70mm, and the thickness of the middle sandwich insulation layer is 60mm.

[0163] Precast reinforced concrete floor slabs: The concrete and steel reinforcement materials are the same as those of the shear walls. The upper and lower floor slabs are 50mm thick reinforced concrete floor slabs, and the sandwich layer is 50mm thick XPS extruded polystyrene board.

[0164] Precast foundation: The concrete and steel reinforcement materials are the same as those for the shear wall.

[0165] The specifications for bolted connection nodes are as follows:

[0166] In the concentrated dry bolted shear wall structure system, a two-node connection method is used between the wall panel and the foundation. Each node is connected using a steel plate as shown in Figure 4(a). The steel plate is made of Q235 steel, with a thickness of 6mm and a width of 190mm. Each steel plate is reliably connected using eight 10.9s grade M20 bolts. Two bolted connection nodes are typically arranged at the horizontal and vertical joints where the wall panels meet. The steel plate dimensions are shown in Figures 4(b) and 4(c), respectively.

[0167] Actual rendering of a demonstration project of a fully dry bolted shear wall structure system in a concentrated area is shown below. Figure 14As shown, according to the "two-stage" design concept of the "Code for Seismic Design of Buildings" (GB50011-2010), the first stage is the design stage of the bearing capacity of components under frequent earthquakes.

[0168] From steps 1 and 2, taking the most unfavorable internal force calculation of a 4300mm wall panel as an example, the calculated axial force, shear force and bending moment of the horizontal joint are 114.8kN, 30.2kN and 92.7kN·m, respectively.

[0169] From step 3, the bearing capacity of the bolted connection node can be obtained as: tensile bearing capacity of the steel plate N. p The shear capacity of the bolt is 478.80 kN; v,b The shear resistance of the bolt hole wall is 779.11 kN; l The tensile bearing capacity of the bolted connection node is 100.37 kN; j The minimum value among the three is taken as 100.37 kN. Shear bearing capacity V of the steel plate. p The shear capacity V of the bolted connection node is 410.4 kN. j The maximum shear force is 100.37 kN; the horizontal joint bending capacity M0 and shear capacity V0 are calculated to be 752.6 kN·m and 198.42 kN, respectively; the maximum shear force of the vertical joint elastic connection is 21.83 kN.

[0170] Based on the above calculation results, it is determined that the failure mode of the horizontal joint may be the failure of the tension node. Under the seismic fortification intensity of 7 degrees and the design basic seismic acceleration of 0.10g, which is a frequent earthquake condition, there is a large margin in both the shear force and bending moment actually experienced by the horizontal joint, and the bolted connection node is safe and reliable.

[0171] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place", characterized in that, include: Step 1: Use the base shear method for seismic calculation, taking only one degree of freedom for each floor, to determine the total base shear and story shear of the fully dry bolted shear wall structure system at the concentrated location; Step 2: Determine the distribution of floor shear force on each axis shear wall and calculate the horizontal shear force on each axis wall panel; when using cast-in-place floor slabs or precast monolithic concrete floor slabs, the floor shear force of the structure is distributed according to the equivalent stiffness of the lateral force resisting members, that is, according to the lateral stiffness of the precast bolt-connected shear wall panels; when using precast floor slabs, the distribution is based on the proportion of the subordinate area of ​​each axis wall panel; Step 3: Determine the distribution of horizontal shear force among the wall panels on the same axis. The distribution of horizontal shear force among the wall panels does not consider the constraint effect of vertical connection nodes on the wall panels, and follows the principle of distribution according to lateral stiffness. Step 4: Verify the bearing capacity of the bolted connection node based on the calculation results of Steps 1-3, including the tensile bearing capacity and shear bearing capacity of the bolted connection node; Step 5: Based on the calculation results of Steps 1-3, perform load-bearing capacity verification at horizontal and vertical joints, including verification of the flexural capacity of horizontal joints, verification of the shear capacity of horizontal joints, and verification of the shear capacity of vertical joints. Step 6: Based on the verification results of Step 4 and Step 5, conduct the first stage seismic design analysis of the concentrated part of the fully dry bolted shear wall structure, and evaluate the structural safety performance and optimize the node layout. Step 5 specifically includes the following sub-steps: When the horizontal joint section still satisfies the plane section assumption, under horizontal seismic action, the horizontal joint of the wall bears axial force, shear force and bending moment. When bending failure occurs, the end concrete is under pressure and the joint is under tensile stress. The typical failure mode is that the concrete in the compression zone collapses and the outermost tension joint fails. Based on the vertical force balance and bending moment balance of the section under the ultimate state, the bending bearing capacity of the horizontal joint of the precast bolted shear wall panel is verified. ； ； ； In the formula, The tension at the i-th connected node. The height of the concrete compression zone. This is the design value of the axial compressive strength of concrete. The equivalent thickness of the prefabricated bolted shear wall panel. , For concrete specification coefficients, when the concrete strength grade does not exceed C50, they are taken as 1.0 and 0.8 respectively; Calculate the relative limiting height of the compression zone when tension joint failure and compression zone concrete occur simultaneously. : )； ； We will assume, firstly, that the wall panel fails at a tension joint. = , Calculate the height of the compression zone to obtain the design value of the tensile bearing capacity of the bolted connection joint. , and relative pressure zone height : ； Compare and ,like If the above assumptions are correct, the tension node will fail first. The flexural capacity of the horizontal joint can be calculated according to the moment equilibrium rule. ;on the contrary, The concrete in the end compression zone fails before the tension joint. The actual tensile force It can be obtained from the following formula: ； ； Will Substituting into the above formula, we obtain the new height of the pressure zone. And the new horizontal joint flexural bearing capacity; In the formula, The elastic modulus of steel; This represents the ultimate compressive strain of concrete under non-uniform compression. The tensile strain caused by bolt joint slippage can be taken as the gap between the bolt hole wall and the bolt. Distance between the resultant point of the upper wall panel bolts and the resultant point of the lower wall panel bolts The ratio; The tensile strain caused by the tension at the node when the boundary fails; Horizontal joint shear bearing capacity Provided by the shear capacity of the bolted connection joint and the frictional force of the horizontal joint section: ； In the formula, This refers to the number of bolted joints in the horizontal seam. The coefficient of friction between the upper and lower wall panels; This is the design value for the axial force perpendicular to the mating surface; it is positive for compression and negative for tension. Based on the horizontal shear force experienced by the precast bolt-connected shear wall panel, the shear capacity of the vertical joint is verified: ； ； In the formula, coefficient 1.2 is an amplification factor that takes into account the influence of other factors. The horizontal shear force of the wall panel; , These are the height and width of the wall panel, respectively. For the shear bearing capacity of the vertical connection nodes, This represents the number of vertically connected nodes.

2. The seismic design method for a fully dry bolted shear wall structure with "non-equal cast-in-place" seismic resistance according to claim 1, characterized in that, In step 2, the method for calculating the lateral stiffness of the prefabricated bolt-connected shear wall panel includes: Treating precast bolt-connected shear wall panels as cast-in-place walls, the initial stiffness decreases due to the presence of joints. Therefore, a lateral stiffness reduction factor for precast bolt-connected shear wall panels is introduced. Define the lateral stiffness reduction factor for precast bolted shear wall panels. Based on the results of parameter analysis, a simplified calculation formula for the lateral stiffness reduction factor of precast bolted shear wall panels is fitted and regressed, including four parameters: bolt joint steel ratio, wall height-to-width ratio, axial compression ratio, and relative joint position. The formula is as follows: ； ； ； ； ； ； In the formula, To improve the lateral stiffness of prefabricated bolted shear wall panels, For the lateral stiffness of cast-in-place walls of the same size, For the steel ratio of bolted joints, The aspect ratio of the wall panel. This represents the relative position of the node. The axial compression ratio, This is the design value of the axial compressive strength of concrete. , These refer to the height, width, and thickness of the precast bolt-connected shear wall panels. To connect the cross-sectional areas of the steel plates, This refers to the distance from the bolt connection node to the edge of the wall. This is the axial force.

3. The seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place" according to claim 2, characterized in that, In step 2, for a single precast bolted shear wall panel, its lateral stiffness is calculated based on the lateral stiffness of a cast-in-place wall of the same size, multiplied by a lateral stiffness reduction factor. However, for multiple wall panels spliced ​​together along the same axis through bolted joints, the constraint effect of vertical joints on the wall panels is ignored, and its overall stiffness is equal to the sum of the stiffnesses of each wall panel, i.e.: 。 4. The seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place" according to claim 3, characterized in that, In step 4, for bolted joints, there are three failure modes under tension: tensile yielding failure of the connecting steel plate, shear failure of the high-strength bolts, and shear punching shear failure of the concrete surrounding the bolt holes in the tension zone. The bearing capacity calculation formula for each failure mode is as follows: ； ； ； ； in, , , , These are the tensile bearing capacity of the steel plate, the shear bearing capacity of the bolt, the punching shear bearing capacity of the bolt hole wall, and the tensile bearing capacity of the bolt connection joint. , , , , These are the tensile strength of steel plates, the shear strength of high-strength bolts, the axial tensile strength of concrete, and the design values ​​of the tensile strength of stirrups and reinforcing bars, respectively. , , These represent the number of steel plates, bolts, and shear surfaces of the bolts in the connection node, respectively. , , These are the tensile cross-sectional area of ​​the connecting steel plate, the total stirrups intersecting the oblique section of the 45° punching failure cone and passing through the top surface of the punching body, and the cross-sectional area of ​​the vertical reinforcing bars, respectively. The diameter of the screw; To calculate the perimeter of the cross section; To calculate the effective height of the inclined section.

5. The seismic design method for a fully dry bolted shear wall structure that is "not equivalent to cast-in-place" according to claim 4, characterized in that, In step 4, when the bolted connection fails under shear, there are two failure modes: shear failure of the connecting steel plate and shear failure of the high-strength bolts. The bearing capacity calculation formula for each failure mode is as follows: ； ； in, , These are the shear bearing capacity of the steel plate and the shear bearing capacity of the bolted connection joint, respectively. The shear strength of the steel plate; This represents the shear cross-sectional area of ​​the steel plate.

6. The seismic design method for "non-equal cast-in-place" shear wall structures with fully dry bolted connections according to any one of claims 1-5, characterized in that, The seismic effect analysis of the concentrated part of the fully dry bolted shear wall structure system was completed by constructing a simplified mechanical model of the prefabricated bolted shear wall panel structure, which replaces the work in steps 1 to 3.

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