Prestressed reinforced masonry shear wall and design method thereof

Abstract

The application provides a prestressed reinforced masonry shear wall and a design method thereof, and belongs to the technical field of building structure engineering. The design method is suitable for a prestressed reinforced masonry shear wall of a multi-storey shear wall structure, can reduce the consumption of steel bars, effectively improve the self-resetting performance of the structure under the action of a large earthquake, and thus improves the seismic performance of the structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building structure engineering, and particularly relates to a prestressed reinforced masonry shear wall and a design method thereof. BACKGROUND

[0002] Anti-seismic is one of the key performances that need to be considered in building structures. Ordinary reinforced concrete structures have been unable to meet the anti-seismic requirements, especially the anti-seismic requirements of multi-story buildings. Under normal use and small earthquake action, ordinary reinforced concrete structures rely on the cooperative work of ordinary reinforcement and masonry, but the brittle characteristics of masonry materials easily lead to wall body cracking, and the cracks are difficult to control, which not only affects the durability of the structure, but also may cause functional problems such as leakage. Under medium and large earthquake, although ordinary reinforced concrete structures can dissipate part of the seismic energy through plastic deformation, the residual deformation is large after the wall body is damaged, and it is difficult to self-reset, resulting in degradation of stiffness and bearing capacity, and even the risk of progressive collapse may be caused due to cumulative damage.

[0003] In the field of multi-story buildings, reinforced masonry shear wall structures are widely used in multi-story buildings due to their good bearing capacity, convenient construction, and economical cost, and have become a common form of residential, office buildings and other civil buildings. However, the traditional reinforced masonry shear wall has natural shortcomings in terms of seismic performance, which limits its promotion in earthquake-prone areas. From the performance limitations, the traditional reinforced masonry shear wall needs to be configured with a large amount of steel bars for seismic design, which will increase the material cost and construction difficulty, which is contrary to the trend of green and low-carbon industry development.

[0004] The existing seismic design method also has technical pain points. The current specification mainly ensures safety by limiting the height of the building, the height-width ratio, setting up a shock-absorbing joint, and improving the strength grade of the material, but it does not fundamentally solve the problem of brittle failure of masonry structures, and the post-earthquake repair cost is high and the cycle is long.

[0005] With the promotion of urbanization and the improvement of anti-seismic fortification standards, the anti-seismic safety requirements of masonry buildings are becoming increasingly stringent, especially in earthquake-prone areas, the post-earthquake residual deformation and repair difficulty of the traditional reinforced masonry shear wall have restricted its promotion. The building industry has an urgent need to reduce steel consumption and improve construction efficiency. Under this background, the development of a new type of reinforced masonry shear wall structure with good bearing performance, seismic performance and economic advantage has become an important direction to solve the anti-seismic problem of multi-story masonry buildings and promote the development of green buildings. SUMMARY

[0006] The present application is based on the discovery and realization of the inventors on the following facts and problems: although prestressed technology is maturely applied in concrete structures, there is a technical gap in reinforced masonry shear wall structures, the reinforced masonry shear wall will experience multiple stages such as elasticity, cracking, prestress relaxation, and block slip under the combined action of prestress and external load, and its nonlinear mechanical model is difficult to accurately establish. Especially, the reciprocating load under the action of earthquake will cause prestress loss and wall stiffness degradation, and the existing design method based on the prestress theory of concrete structure is difficult to be directly applied to the reinforced masonry shear wall structure. How to realize the cooperative work of prestressed reinforcement and block masonry and meet the differentiated design under different seismic actions is still an industry problem.

[0007] The present application aims to at least solve one of the technical problems in the related art. To this end, embodiments of the present application propose a prestressed reinforced masonry shear wall and a design method thereof. The design method helps to improve the seismic performance of the masonry shear wall, improve the ductility, deformation capacity and bearing capacity of the structure, and provides a reliable theoretical basis for the application of the masonry shear wall as a structural component in multi-story buildings.

[0008] Embodiments of the present application propose a design method of a prestressed reinforced masonry shear wall, comprising the following steps:

[0009] S1. According to the importance of the building, the use function, the seismic fortification intensity, the seismic performance target of the prestressed reinforced masonry shear wall is determined, and the seismic performance level is set;

[0010] S2. According to the seismic performance target and the seismic performance level, the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall are determined in combination with the architectural drawings;

[0011] S3. The bearing capacity of the prestressed reinforced masonry shear wall under multiple load combinations is calculated according to the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall, so that the calculation result meets the bearing capacity design requirements under multiple load combinations;

[0012] S4. The bearing capacity of the prestressed reinforced masonry shear wall is calculated under normal use conditions and small earthquake action, so that the calculation result meets the bearing capacity design requirements under normal use conditions and small earthquake action;

[0013] S5. The ultimate bearing capacity of the prestressed reinforced masonry shear wall is calculated under the action of medium earthquake and large earthquake, so that the calculation result meets the bearing capacity design requirements under the action of medium earthquake and large earthquake;

[0014] S6. If the calculation results of steps S3, S4 and S5 do not meet the design requirements, adjusting the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall and recalculating until the calculation results meet the design requirements; selecting and arranging the prestressed steel according to the calculation results of steps S3, S4 and S5.

[0015] S7. Determining the anchoring device of the prestressed steel, and completing the design of the prestressed reinforced masonry shear wall.

[0016] The design method of the embodiment of the application has the following advantages and technical effects:

[0017] (1) Compared with the traditional technical solution, the design method of the prestressed reinforced masonry shear wall provided by the embodiment of the application provides an innovative solution for the development of multi-story masonry buildings. By introducing the prestressed reinforcement technology, the design method successfully constructs a new type of masonry shear wall structure, providing a solid technical guarantee for the safe application of multi-story masonry buildings under complex geological conditions.

[0018] (2) The design method of the prestressed reinforced masonry shear wall provided by the embodiment of the application has the core innovation that by reasonably configuring the prestressed steel, core concrete and structural steel, the masonry shear wall can realize the bearing capacity performance and seismic performance comparable to the concrete shear wall.

[0019] (3) The design method of the prestressed reinforced masonry shear wall provided by the embodiment of the application optimizes the steel configuration to reduce material consumption, provides an innovative solution for the seismic design of masonry shear wall structure, effectively improves the bearing performance and lateral capacity of masonry shear wall at different load stages, and enhances the overall seismic performance of the building.

[0020] Optionally, in step S2, determining the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall specifically includes: preliminarily determining the wall size, length, height, thickness, block type and strength grade, core concrete mix proportion, and preliminarily determining the specifications, quantities and arrangement positions of the stress steel, structural steel and prestressed steel.

[0021] Optionally, in step S3, the multiple load combinations include combinations of vertical loads and horizontal loads, wherein the vertical loads include structural self-weight and floor live load, and the horizontal loads include wind load and seismic load.

[0022] Optionally, step S4 specifically comprises the following steps: under normal use conditions and small earthquake action, considering vertical load and horizontal load under small earthquake action, calculating internal force and deformation of the wall, ensuring that the wall meets normal use requirements, including meeting axial compression resistance capacity and lateral bending resistance capacity requirements, controlling horizontal displacement and vertical displacement to ensure overall stability of the structure and use function, and simultaneously optimizing wall performance by adjusting prestressed steel bar tension stress and steel bar arrangement.

[0023] Optionally, in step S4,

[0024] For the wall body bearing axial compression, it is required to meet ;

[0025] When the wall body is not greater than 99,

[0026] When the wall body is greater than 99,

[0027]

[0028]

[0029] wherein, h is the wall height, r is the radius of gyration, and e is the eccentricity, f a is the axial compressive stress of the masonry, f b is the axial bending stress of the masonry, F a is the design value of axial compressive strength of the masonry, F b is the design value of bending compressive strength of the masonry, f' m is the standard value of compressive strength of the masonry, unit: MPa, P is the axial load, P e is the elastic yield critical load of the axial compression member, E m is the elastic modulus of the masonry, I n is the moment of inertia of the net section.

[0030] Optionally, in step S4, the design bending moment strength is taken as the theoretical bending moment strength M n multiplied by a strength reduction coefficient Ø, and Ø=0.8;

[0031] For the cross section B with uniform width over the depth of the compression zone, the depth of the equivalent compressive stress block is a ,

[0032] ;

[0033] where, a is the equivalent compression zone height in mm; f ps is the ultimate stress of the prestressed reinforcement in MPa; A ps is the cross-sectional area of the prestressed reinforcement in mm 2 ; A s is the cross-sectional area of the longitudinal reinforcement in mm 2 ; f y is the standard value of the yield strength of the reinforcement and anchorage in MPa; P u is the design value of the axial load in N; f' m is the standard value of the compressive strength of the masonry in MPa; b is the cross-sectional width in mm; strength reduction factor , = 0.8;

[0034] The moment strength of a prestressed masonry shear wall with a width of b M n is calculated by the following formula:

[0035] ,

[0036] where, d is the effective height of the cross section in mm, M n is the flexural capacity in MPa;

[0037] d shall be calculated as the actual distance from the centerline of the tendon to the compression face of the member. For prestressed tendons and for walls loaded out of plane, d shall not exceed the face shell thickness plus one-half the diameter of the tendon plus 0.95 cm. When tendons are not placed in the center of the wall, d shall be calculated for each direction of out-of-plane bending.

[0038] Optionally, in step S4, for a prestressed masonry shear wall, the effective prestress of the prestressed reinforcement f se is calculated by the following formula:

[0039] ;

[0040] where,f se effective prestress of prestressed reinforcement; E ps elastic modulus of prestressed reinforcement; net length of prestressed reinforcement; f ps ultimate state stress of prestressed reinforcement, unit: MPa; A ps cross-sectional area of prestressed reinforcement, unit: mm 2 ; f' m standard value of compressive strength of masonry, unit: MPa.

[0041] Optionally, in step S4, the shear strength of the prestressed reinforced masonry shear wall is calculated by using the following a), b), c) formulas, and the minimum value is taken,

[0042] a) ;

[0043] b) ;

[0044] c) ;

[0045] If , ;

[0046] If , ;

[0047] wherein V n is the shear design value, unit: N, V ns is the stirrup shear design value, unit: N, V nm is the masonry shear design value, unit: N, A nv is the net shear area, unit: m 2 ; gamma g is a coefficient related to the grouting condition of the wall, for the prestressed reinforced masonry shear wall with partial grouting , otherwise .

[0048] Optionally, in step S5, the maximum applied stress of the prestressed reinforcement shall not exceed 0.8 times the specified tensile strength of the prestressed reinforcement and 0.94 times the specified yield strength of the prestressed reinforcement; after the prestress is transferred to the masonry shear wall, the stress in the prestress shall not exceed 0.82 times the yield strength and 0.74 times the ultimate tensile force; when the prestress is applied, the prestress at the anchorage device and the connector shall not exceed 0.78 times the yield strength and 0.7 times the ultimate stress.

[0049] Optionally, in step S6, according to the calculation results of steps S3-S5, the arrangement mode of the prestressed steel bars in the wall body is determined in combination with the structural stress characteristics and the prestress distribution, and the arrangement mode includes the number, the spacing, the tension end and the fixed end position and the like; the selection of the prestressed steel bars needs to comprehensively consider the strength grade, the relaxation performance and the fatigue performance, and the low-relaxation steel strand with a standard tensile strength not less than 1860 MPa and a 1000h relaxation rate not greater than 2.5% is preferentially selected, and the over-tensioning ratio is determined according to the prestress loss value, but the over-tensioning value should not exceed the maximum tension control stress limit value of the standard value of the prestressed steel bar strength not more than 75%.

[0050] In a second aspect, the embodiments of the present application provide a prestressed reinforced masonry shear wall, which comprises a prefabricated hollow block unit, prestressed steel bars, construction steel bars, core concrete and anchoring devices of the prestressed steel bars; the prefabricated hollow block unit comprises concrete hollow blocks, aerated concrete blocks and fly ash blocks, and the blocks have holes; the prestressed steel bars are arranged in the holes of the blocks in the height direction of the shear wall, and both ends are provided with anchoring devices; the construction steel bars comprise horizontally distributed construction steel bars and vertically distributed construction steel bars, the horizontally distributed construction steel bars are arranged in the horizontal mortar joints of the blocks, and the vertically distributed construction steel bars are located in the holes of the blocks; the prestressed reinforced masonry shear wall is obtained by the design method of the first aspect.

[0051] The prestressed reinforced masonry shear wall of the embodiments of the present application has the following advantages and technical effects:

[0052] (1) The prestressed reinforced masonry shear wall of the embodiments of the present application can enhance the integrity of the wall body, inhibit the generation of cracks under normal use and small earthquakes by introducing prestressed steel bars and anchoring devices, realize self-resetting and reduce residual deformation under medium earthquakes and large earthquakes, ensure that the shear wall has sufficient stiffness and bearing capacity, ensure that the shear wall has good bearing performance and lateral resistance capacity in different load stages, and improve the overall seismic performance of the structure.

[0053] (2) Compared with the traditional reinforced masonry shear wall, the prestressed reinforced masonry shear wall has significant advantages in structural performance. First, the introduction of prestressed reinforcement significantly improves the energy dissipation capacity of the wall. Under the action of earthquake, the cooperative deformation mechanism between prestressed reinforcement and masonry can effectively dissipate seismic energy and reduce the degree of structural damage. Second, its excellent deformation performance enables the wall to maintain structural integrity under large deformation and avoid brittle failure. More significantly, through the active constraint effect of prestress, the generation and development of wall cracks are effectively controlled, forming a more regular and controllable crack distribution pattern, which greatly improves the seismic toughness of the structure. These technical advantages not only significantly improve the safety of multi-story masonry buildings, but also open up new paths for the application of green, environmentally friendly and cost-effective building materials in structural engineering, and have important engineering application value and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 A structural schematic diagram of a prestressed reinforced masonry shear wall is shown.

[0055] Figure 2 A structural schematic diagram of a prefabricated hollow block unit is shown.

[0056] BRIEF DESCRIPTION OF DRAWINGS:

[0057] 1-prefabricated hollow block unit, 2-cored concrete; 3-horizontal distribution construction steel; 4-vertical distribution construction steel; 5-prestressed reinforcement, 6-anchoring device. DETAILED DESCRIPTION

[0058] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0059] In a first aspect, the embodiments of the present application provide a design method of a prestressed reinforced masonry shear wall suitable for a multi-story shear wall structure, comprising the following steps:

[0060] S1. According to the importance of the building, the core use function and the seismic fortification intensity of the region and other factors, the seismic performance target of the shear wall is accurately determined, and the appropriate seismic performance level is set.

[0061] The seismic performance target can be divided into multiple levels. Under the action of small earthquakes, the shear wall remains in an elastic state, and the inter-story drift angle is strictly controlled within the limit value range specified in the Code for Seismic Design of Buildings. The inter-story drift angle of multi-story masonry structures is generally not greater than 1 / 1000. Under the action of moderate earthquakes, the wall may have slight plastic deformation, but the damage is controlled within the repairable range, such as a crack width of <0.2 mm, and does not affect the integrity of the structure. The structure needs to maintain overall stability to avoid local collapse. Under the action of strong earthquakes, the wall may have obvious plastic deformation to dissipate seismic energy, but the overall structure needs to avoid collapse, and the key load-bearing parts need to maintain load-carrying capacity.

[0062] S2. Based on the determined seismic performance target and seismic performance level, the structure is designed in combination with the architectural construction drawings to determine the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall.

[0063] The specific process is as follows. First, the key dimensions of the wall, such as length, height, and thickness, are preliminarily determined. The wall size setting needs to consider three factors: first, the architectural space use demand to avoid unreasonable wall size compression of the internal use space; second, the structural stress characteristics to ensure that the wall can effectively transfer and disperse loads; and third, the matching of block specifications to coordinate the wall size and block module, reducing on-site cutting operations. Then, the type and strength grade of the block, such as concrete hollow block, aerated concrete block, etc., and the appropriate core concrete mix proportion are determined. At the same time, based on the structural stress calculation of the prestressed reinforced masonry shear wall, the specifications, quantities, and arrangement positions of the structural steel and prestressed steel are preliminarily determined. According to the stress analysis of the wall, the vertical and horizontal arrangement methods of the structural steel in the wall, the setting of the prestressed steel in the key parts, and the planning of the prestressed steel tensioning method such as pretensioning or post-tensioning are determined to ensure that the prestress can effectively play a role.

[0064] S3. Based on the selected design parameters and arrangement scheme of the prestressed reinforced masonry shear wall, the bearing capacity calculation under multiple load combinations is carried out. The calculation needs to cover different combinations of vertical loads (such as structural self-weight, floor live load, etc.) and horizontal loads (such as wind load, seismic load, etc.). According to relevant building structure design standards such as the Code for Seismic Design of Buildings and the Code for Design of Masonry Structures, the compressive and shear bearing capacities of the wall are calculated in detail to ensure that the wall has sufficient bearing capacity under the design load. If the calculation does not meet the preset bearing capacity requirements, the design parameters need to be adjusted, which can be done by increasing the number of load-bearing steel or prestressed steel, optimizing the size parameters of the wall such as length, height, and thickness, replacing higher strength grade steel types, or adjusting the prestressed tension control stress size. After adjustment, the bearing capacity calculation process is executed again until the results meet the design requirements.

[0065] S4. Calculate the bearing capacity of the prestressed reinforced masonry shear wall under normal use conditions and small earthquake action to meet the requirements of normal use and use under small earthquake action.

[0066] The calculation needs to consider the vertical loads such as self-weight, floor live load, and horizontal load under small earthquake action. By analyzing the internal forces and deformations of the wall under these load combinations, the wall structure performance is ensured to meet the requirements of building normal use. For bearing capacity requirements, the axial compressive bearing capacity and shear bearing capacity of the wall, as well as the lateral bending capacity of the wall structure under load action are calculated. For deformation control, the horizontal displacement and vertical displacement of the wall are calculated to ensure that the deformation is within the limit value, avoiding affecting the overall stability of the structure and the use function. By adjusting the design parameters such as prestressed steel bar tension stress and steel bar arrangement, the performance of the wall under normal use conditions and small earthquake action is optimized.

[0067] (1) For the wall subjected to axial compression, the following design method should be used:

[0068] ;

[0069] When the wall's is not greater than 99,

[0070] When the wall's is greater than 99,

[0071]

[0072]

[0073] where, h is the wall height,

[0074] r is the radius of gyration,

[0075] e is the eccentricity,

[0076] f a is the masonry axial compressive stress,

[0077] f b is the masonry axial bending stress,

[0078] F a is the masonry axial compressive strength design value,

[0079] F b is the masonry bending compressive strength design value,

[0080] f' m is the standard value of compressive strength of masonry, unit: MPa,

[0081] P is the axial load,

[0082] P e is the elastic yield critical load of axial compression member,

[0083] E m is the elastic modulus of masonry,

[0084] I n is the moment of inertia of the net section.

[0085] For prestressed reinforced masonry shear wall with transverse unrestrained reinforcement, the prestress of prestressed reinforcement P ps should be included in the calculation of axial load P .

[0086] For prestressed reinforced masonry shear wall with transverse restrained reinforcement, the prestress P P ps should not be considered when calculating axial load

[0087] (2) The design bending moment strength should be taken as the theoretical bending moment strength M n multiplied by the strength reduction coefficient , =0.8.

[0088] For cross section B with uniform width in the depth of compression zone, the depth of equivalent compressive stress block a should be determined by the following formula:

[0089] ;

[0090] where, a is the equivalent compression zone height, unit: mm,

[0091] f ps is the ultimate state stress of prestressed reinforcement, unit: MPa,

[0092] A ps is the cross-sectional area of prestressed reinforcement, unit: mm 2 ,

[0093] A s ​A is the cross-sectional area of the longitudinal reinforcement, in mm2 2 ,

[0094] f y fy is the characteristic value of the yield strength of the reinforcement and anchorage, in MPa,

[0095] P u P is the design value of the axial load, in N,

[0096] f' m fc is the characteristic value of the compressive strength of the masonry, in MPa,

[0097] b b is the width of the section, in mm.

[0098] The moment strength of a prestressed reinforced masonry shear wall of width b M n shall be calculated by the following formula:

[0099] ;

[0100] where, d h is the effective height of the section, in mm,

[0101] M n M is the moment strength, also known as the flexural capacity, in MPa.

[0102] Distance d shall be calculated as the actual distance from the centerline of the tendon to the compression face of the member. For prestressed tendons and for walls loaded out-of-plane, d shall not exceed the face shell thickness plus one-half the diameter of the tendon plus 0.95 cm.

[0103] When the tendon is not placed in the center of the wall, the distance d shall be calculated for each direction of out-of-plane bending.

[0104] For walls with prestressed reinforcement, the effective prestress of the prestressed reinforcement shall be permitted to be calculated using the following formula f ps :

[0105] ;

[0106] where, f se Pp is the effective prestress of the prestressed reinforcement,

[0107] E ps E is the modulus of elasticity of the prestressed reinforcement,

[0108] Lp is the net length of prestressed reinforcement,

[0109] f ps fpu is the ultimate stress of prestressed reinforcement, unit: MPa,

[0110] A ps Ap is the cross-sectional area of prestressed reinforcement, unit: mm 2 ,

[0111] f' m f'm is the standard value of compressive strength of masonry, unit: MPa.

[0112] (3) The shear strength of prestressed reinforced masonry shear wall is calculated by the following a), b), c) three formulas, and the minimum value is taken.

[0113] a) ;

[0114] b) ;

[0115] c) ;

[0116] Wherein V n Not more than the following values:

[0117] If , ;

[0118] If , ;

[0119] For partially grouted prestressed reinforced masonry shear wall , otherwise ;

[0120] V n is the shear design value, unit: N,

[0121] V ns is the shear design value of stirrup, unit: N,

[0122] V nm is the shear design value of masonry, unit: N,

[0123] A nv is the net shear area, unit: m 2 .

[0124] S5. Under the action of medium and large earthquakes, the ultimate bearing capacity of the prestressed reinforced masonry shear wall is calculated, and the performance requirements of the corresponding earthquake level in the Code for Seismic Design of Buildings must be strictly met.

[0125] The calculation needs to consider the vertical loads such as self-weight and live load of the floor, as well as the horizontal loads under the action of medium and large earthquakes. By analyzing the internal forces and deformations of the wall under these load combinations, it is ensured that the wall structure performance meets the requirements and meets the requirements of the normal use of the building. For the bearing capacity requirements, the axial compressive bearing capacity and shear bearing capacity of the wall, as well as the lateral bending capacity of the wall structure under the action of loads are calculated. For deformation control, the horizontal displacement and vertical displacement of the wall are calculated to ensure that the deformation is within the limit value, avoiding affecting the overall stability of the structure and the use function. For specific calculation formulas, refer to the calculation formulas in step S4.

[0126] The maximum applied stress of the prestressed steel should not exceed 0.8 times the specified tensile strength of the prestressed steel and 0.94 times the specified yield strength of the prestressed steel. After the prestress is transferred to the masonry shear wall, the stress in the prestress should not exceed 0.82 times the yield strength and 0.74 times the ultimate tensile force. When applying prestress, the prestress at the anchorage device and connector should not exceed 0.78 times the yield strength and 0.7 times the ultimate stress.

[0127] The calculation needs to focus on the plastic deformation capacity, stiffness degradation law and ultimate bearing state of the wall under the action of cyclic loads, to ensure that the wall structure is damage controllable under medium earthquakes and does not collapse under large earthquakes.

[0128] If the calculation results do not meet the ultimate bearing capacity requirements of the Code for Seismic Design of Buildings, edge component restraining stirrups can be added to enhance the restraining capacity of the edge region of the wall, improve the strength grade of the core concrete, improve the compressive strength and ductility of the core area concrete by optimizing the mix proportion, enhance the overall stress performance of the wall, adjust the arrangement of the prestressed steel and the control stress of the prestress, further play the self-resetting role of the prestress, and improve the bearing redundancy of the wall under large deformation. After optimization, the ultimate bearing capacity calculation and analysis need to be performed again until the performance targets under the action of medium and large earthquakes are met.

[0129] S6. According to the calculation results, the selection and arrangement of the prestressed steel are performed.

[0130] If the results of any one of steps S3, S4 and S5 do not meet the design requirements, the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall are adjusted and recalculated until the calculation results meet the design requirements (i.e. relevant building structure design standards such as Code for Seismic Design of Buildings and Code for Design of Masonry Structures). After the calculation results of the previous steps meet the design requirements, the arrangement of the prestressed reinforcement in the wall is determined according to the calculation results of the previous steps in combination with the stress characteristics of the structure and the calculated prestress distribution, including the number, spacing, tension end and fixed end positions of the prestressed reinforcement. The selection of the prestressed reinforcement should consider indicators such as strength grade, relaxation performance and fatigue performance.

[0131] Low-relaxation steel strands with a standard tensile strength not less than 1860 MPa are preferably selected, and their relaxation rate should meet the specification requirements, with a 1000h relaxation rate not greater than 2.5%. The arrangement of the prestressed reinforcement should be combined with the stress characteristics of the wall and the seismic performance requirements. The prestressed reinforcement should be reasonably arranged in the tensile and compression regions of the wall to effectively control the crack development of the wall and improve the self-centering ability. The arrangement spacing should meet the minimum spacing requirements of the prestressed reinforcement in the specification to avoid concrete pouring not being dense due to too small spacing. At the same time, the arrangement of the tension end and fixed end of the prestressed reinforcement should be considered to ensure the feasibility and safety of the tensioning construction. According to the prestress loss value obtained by structural calculation, the over-tensioning ratio of the prestressed reinforcement is determined, but the over-tensioning value should not exceed the maximum tension control stress limit value specified in the specification, i.e. not more than 75% of the standard strength value of the prestressed reinforcement. Through the above selection and arrangement, the mechanical properties of the prestressed reinforcement can be fully utilized to ensure that the wall works cooperatively with the blocks and core concrete in each stress stage and improves the overall seismic performance of the structure.

[0132] S7. Select a reliable prestressed reinforcement anchoring device to complete the design of the prestressed reinforced masonry shear wall.

[0133] For the anchoring of the prestressed reinforcement in the prestressed reinforced masonry shear wall structure, mechanical anchoring or adhesive anchoring should be selected according to the construction process and stress requirements, and the following requirements should be met: the anchoring efficiency coefficient of the mechanical anchoring device directly supported on the masonry or placed in the concrete end block or completely inside the grouted masonry should not be less than 0.95 to ensure that the prestress is effectively transmitted to the wall; and it needs to pass the fatigue performance test to meet the durability requirements under repeated loads in seismic design to avoid prestress loss due to anchoring failure. Adhesive anchoring is commonly used in pretensioning method construction or part of the non-tension end in post-tensioning method. The length of adhesive anchoring should be determined according to the Code for Design of Concrete Structures, considering factors such as steel diameter, concrete strength grade, prestress transmission length, etc., to ensure that the adhesive force is sufficient to resist the tension generated by the prestress. Through the reasonable selection of the above anchoring methods, the prestressed reinforcement can work cooperatively with the wall to ultimately complete the overall design of the prestressed reinforced masonry shear wall.

[0134] In a second aspect, embodiments of the present application provide a prestressed reinforced masonry shear wall, as shown in Figure 1 and Figure 2 The prestressed reinforced masonry shear wall comprises a prefabricated hollow block unit 1, a prestressed steel bar 5, a construction steel bar, a core concrete 2, and an anchoring device 6 of the prestressed steel bar; the prefabricated hollow block unit 1 comprises a load-bearing block such as a concrete hollow block, an aerated concrete block, and a fly ash block, and the block has a hole; the prestressed steel bar 5 is arranged in the hole of the block in the height direction of the shear wall, and both ends are provided with an anchoring device; the construction steel bar comprises a horizontally distributed construction steel bar 3 and a vertically distributed construction steel bar 4, the horizontally distributed construction steel bar 3 is arranged in the horizontal mortar joint of the block, and the vertically distributed construction steel bar 4 is located in the hole of the block; the prestressed reinforced masonry shear wall is obtained by the design method of the first aspect.

[0135] The application will be described in detail below with reference to the embodiments and drawings.

[0136] A design method of a prestressed reinforced masonry shear wall suitable for a multi-layer shear wall structure, comprising the following steps:

[0137] 1. Precisely determine the overall structural performance target according to the use function, safety standard, and site conditions of the building, and other factors. This target needs to be determined by comprehensively considering various requirements of the building in the normal use process, and the safety requirements in the possible extreme situations (such as earthquakes, strong winds, etc.). Then, the ordinary structure is designed according to the building scheme, and the ordinary structure design needs to follow the relevant building design specifications and mechanical principles to ensure the preliminary rationality and feasibility of the structure.

[0138] 2. Accurately determine the specific position of the prestressed reinforced masonry shear wall in the building by comprehensively considering factors such as the spatial layout, stress characteristics, and seismic requirements of the building. These positions are usually the key parts in the structure where the stress is more concentrated and has a greater impact on the overall stability. At the same time, according to the size, height, load size, and other conditions of the building, the size of the prestressed reinforced masonry shear wall is reasonably determined, including the length, thickness, and height of the wall, so as to ensure that the wall can effectively bear and transfer the load.

[0139] 3. According to the seismic fortification intensity and site category of the region where the building is located, the seismic performance requirements of the building are determined. This includes specific indicators such as the deformation capacity, energy dissipation capacity, and collapse resistance of the structure under the action of earthquakes. At the same time, combined with the use function and design standard of the building, the bearing capacity design requirements of the structure are determined, covering the bearing capacity requirements of vertical loads (such as dead load, live load, etc.) and horizontal loads (such as wind load, earthquake action, etc.). Then, according to the relevant national building specifications, the combination of various possible loads is calculated to determine the load combination that the structure bears under the most unfavorable working condition.

[0140] 4. Determine the required prestress on the prestressed reinforcement. First, the yield strength of the prestressed reinforcement is determined f py and the specified tensile strength f pu These two important performance indicators. To ensure the safety and reliability of the structure, the required prestress must meet certain limitations, that is, it must not exceed 0.94 f py , and must not exceed 0.8 f pu . After the prestress is transferred to the masonry, the stress in the prestressed reinforcement must also be limited, which must not exceed 0.82 f py or 0.74 f pu ; during the application of prestress, the prestress at the anchor and connector must not exceed 0.78 f py or 0.7 f pu . Through these conditions and in combination with the actual required prestress of the shear wall, the most suitable type of prestressed reinforcement is selected from the existing prestressed reinforcement types on the market. In addition, due to the fact that in actual engineering, the stress of the prestressed reinforcement will be affected by various factors and will be lost, such as the elastic shrinkage of the masonry, the stress loss during anchoring, and the thermal effect, etc., therefore, these factors need to be considered comprehensively, and the effective stress of the prestressed reinforcement is obtained through reasonable calculation method f se .

[0141] 5. For walls subjected to axial compression, the following requirements must be met in the design: to ensure that the stress distribution of the wall under the combined action of axial load and bending load is within a reasonable range, and is controlled through specific stress calculation and proportional relationship, that is

[0142] ; and .

[0143] This limitation is to prevent the wall from being damaged under excessive axial load and to ensure that the wall has sufficient safety reserves when subjected to axial compression.

[0144] For the geometric parameters of the wall h / r (where h is the effective height of the wall and r is the radius of gyration) is not greater than 99, ;

[0145] When h / r is greater than 99, .

[0146] to adapt to the stress characteristics of different geometric features of the wall. Another compressive stress is used to resist bending only F b The standard value of the compressive strength of the masonry is then determined according to a fixed proportional relationship.

[0147] .

[0148] bending load P e The calculation needs to consider the elastic modulus, moment of inertia, wall height, and eccentricity of the wall.

[0149] .

[0150] 6. For prestressed reinforced masonry shear walls with transverse constraint reinforcement, the influence of prestress P ps does not need to be considered when calculating the axial load P M n When determining the design bending moment strength of the wall, the theoretical bending moment strength B should be multiplied by a strength reduction factor Ø, which is 0.8. This reduction is to consider various uncertain factors in actual engineering, such as the dispersion of material properties, differences in construction quality, etc., to ensure the safety of the structure in actual use. For cross-sections with uniform depth and width in the compression zone a the depth of the equivalent compressive stress block needs to be calculated through a specific formula.

[0151] .

[0152] The formula takes into account the size of the prestress applied by the prestressed reinforcement, the area of the prestressed reinforcement, the effective sectional reinforcement area, the yield strength standard value of the reinforcement and anchorage, the design value of the axial load, the compressive strength standard value of the masonry, and the cross-sectional width, etc. to accurately determine the stress distribution in the compression zone.

[0153] For prestressed reinforced masonry shear walls with a width of b, the bending moment strength M n needs to be calculated through the following formula.

[0154]

[0155] The formula takes into account the prestress applied by the prestressed steel bar, the area of the prestressed steel bar, the effective sectional steel bar area, the design value of the axial load, the strength reduction coefficient, the equivalent compression zone height, and the actual distance d from the center line of the steel bar bundle to the compression surface of the component, etc. The distance d should be accurately calculated as the actual distance from the center line of the steel bar bundle to the compression surface of the component. For prestressed steel bar bundles and walls loaded out of the plane, in order to ensure the stress performance and safety of the wall, d The value of d should not exceed the thickness of the face shell plus half the diameter of the steel bar bundle plus 0.95 cm. When the steel bar bundle is not placed at the center of the wall, the value of d should be calculated for each direction of out-of-plane bending to ensure that the wall meets the design requirements under different stress conditions. d

[0156] 7. For prestressed reinforced masonry shear walls, the prestress applied by the prestressed steel bar f ps needs to be calculated by a specific formula.

[0157]

[0158] The formula takes into account the effective stress of the prestressed steel bar f se , the elastic modulus of the prestressed steel bar, the actual distance from the center line of the steel bar bundle to the compression surface of the component, the geometric size of the wall, and the load borne by the wall, etc. to accurately determine the actual stress state of the prestressed steel bar under different working conditions.

[0159] For prestressed reinforced masonry shear walls, the shear strength needs to be calculated by the following a), b), and c) three formulas.

[0160] a) ;

[0161] b) ;

[0162] c) ;

[0163] The minimum value selected from the calculation results of the above three different calculation formulas is taken as the shear strength of the wall. The calculation formula of the prestress applied by the prestressed steel bar f ps and the calculation formula of the shear strength of the wall take into account the standard compressive strength of the masonry and the net shear area, etc. to ensure that the wall has sufficient safety reserves when bearing shear force.

[0164] The wall shear strength calculation formula takes into account the shear strength of the block, the shear strength provided by the shear steel bar, and a coefficient gamma g ​At the same time, the shear strength of the wall is also limited, according to the different ratio of the bending moment strength of the wall to the product of the shear force and the effective height of the wall, different upper limit values are set.

[0165] If , ;

[0166] If , ;

[0167] For partially grouted prestressed reinforced masonry shear walls, gamma g The value is 0.75; for other cases, gamma g The value is 1.

[0168] 8. The prestressed steel in the prestressed reinforced masonry shear wall structure needs to be anchored in a specific way. The specific anchoring methods include: directly supporting the prestressed steel on the masonry, using the bearing capacity of the masonry to fix the prestressed steel; or placing the prestressed steel in the mechanical anchoring device inside the concrete end block or the completely grouted masonry, ensuring the reliable connection of the prestressed steel and the structure through mechanical connection; or using adhesive in the reinforced concrete end block or component to anchor, using the adhesive force to firmly fix the prestressed steel in the structure. The selection and application of these anchoring methods need to be reasonably determined according to the specific engineering situation and design requirements, to ensure that the prestressed steel can effectively play its role and improve the overall performance and safety of the structure.

[0169] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0170] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A design method of prestressed reinforced masonry shear wall, characterized in that, The method comprises the following steps: S1. Determine the seismic performance target of the prestressed reinforced masonry shear wall according to the importance, use function and seismic fortification intensity of the building, and set the seismic performance level; S2. Determine the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall according to the seismic performance target and seismic performance level and in combination with the architectural drawings; S3. Calculate the bearing capacity of the prestressed reinforced masonry shear wall under multiple load combinations according to the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall, so that the calculation result meets the bearing capacity design requirements under multiple load combinations; S4. Calculate the bearing capacity of the prestressed reinforced masonry shear wall under normal use conditions and small earthquake action, so that the calculation result meets the bearing capacity design requirements under normal use conditions and small earthquake action; For walls subjected to axial compression, the following must be satisfied ; When the wall body not greater than 99, When the wall body greater than 99, wherein, h is the height of the wall, r is the radius of gyration, e is the eccentricity, f a is the axial compressive stress of the masonry, f b is the axial flexural stress of the masonry, F a is the axial compressive strength design value of the masonry, F b is the flexural compressive strength design value of the masonry, f' m is the standard value of the compressive strength of the masonry, in MPa, P is the axial load, P e is the elastic yield critical load of the axial compression member, E m is the elastic modulus of the masonry, I n is the moment of inertia of the net section; S5. Calculate the ultimate bearing capacity of the prestressed reinforced masonry shear wall under medium earthquake and large earthquake action, so that the calculation result meets the bearing capacity design requirements under medium earthquake and large earthquake action; S6. If the calculation results of steps S3, S4 and S5 do not meet the design requirements, adjust the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall and recalculate until the calculation result meets the design requirements; select and arrange the prestressed steel bars according to the calculation results of steps S3, S4 and S5; S7. Determine the anchoring device of the prestressed steel bars and complete the design of the prestressed reinforced masonry shear wall.

2. The design method of claim 1, wherein In step S2, the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall specifically include: preliminarily determining the wall size, length, height, thickness, block type and strength grade, core concrete mix proportion, and preliminarily determining the specifications, quantity and arrangement positions of the stress steel bars, structural steel bars and prestressed steel bars.

3. The method of claim 1, wherein, In step S3, the multiple load combinations include the combination of vertical load and horizontal load, wherein the vertical load includes structural self-weight and floor live load, and the horizontal load includes wind load and earthquake load.

4. The method of claim 1, wherein, Step S4 specifically includes the following steps: under normal use conditions and small earthquake action, considering the vertical load and the horizontal load under small earthquake action, wherein the vertical load includes structural self-weight and floor live load, calculating the internal force and deformation of the wall to ensure that the wall meets the normal use requirements, including meeting the axial compression resistance capacity and lateral bending resistance capacity requirements, controlling the horizontal displacement and vertical displacement to ensure the overall stability of the structure and the use function, and simultaneously optimizing the wall performance by adjusting the prestressed steel bar tension stress and steel bar arrangement.

5. The design method according to claim 1 or 4, characterized by, In step S4, the design bending moment strength is taken as the theoretical bending moment strength M n times the strength reduction factor, 0 = 0.8; For a cross section B with uniform width over the depth of the compressive zone, the depth of the equivalent compressive stress block is a , ； wherein, a Hc is the equivalent compression zone height, in mm; f ps fpu is the ultimate stress of prestressed reinforcement, in MPa; A ps Aps is the cross-sectional area of prestressed reinforcement, in mm 2 ; A s As is the cross-sectional area of longitudinal reinforcement, in mm 2 ; f y fy is the characteristic value of yield strength of reinforcement and anchorage, in MPa; P u P is the design value of axial load, in N; f' m fc is the characteristic value of compressive strength of masonry, in MPa; b B is the cross-sectional width, in mm; the strength reduction factor is 0.8, i.e. 0.

8. Moment strength of prestressed reinforced masonry shear walls having a width b M n is calculated by the following equation: ， wherein, d is the cross-sectional effective height in mm; M n is the flexural capacity in MPa; d shall be calculated as the actual distance from the center line of the tendon to the compression surface of the member, in cm; for prestressed tendons and walls loaded out of plane, d shall not exceed the face shell thickness plus half the diameter of the tendon plus 0.95 cm, when the tendon is not placed in the center of the wall, d shall be calculated for each direction of out-of-plane bending; In step S4, for the prestressed reinforced masonry shear wall, the effective prestress of the prestressed steel bar f se It is calculated by the following formula: ； wherein, f se Eeff is the effective prestress of the prestressed reinforcement, E ps Epre is the elastic modulus of the prestressed reinforcement, Lpre is the net length of the prestressed reinforcement, f ps fpre is the ultimate state stress of the prestressed reinforcement, in MPa; A ps Apre is the cross-sectional area of the prestressed reinforcement, in mm 2 ; f' m f' m is the standard value of the compressive strength of the masonry, in MPa; P P is the axial load.

6. The design method of claim 5, wherein, In step S4, the shear strength of the prestressed reinforced masonry shear wall is calculated using the following a), b) and c) formulas, and the minimum value is taken, a） ； b） ； c） ； If , ; If , ; wherein V n is the shear design value, in N, V ns is the stirrup shear design value, in N, V nm is the masonry shear design value, in N, A nv is the net shear area, in m 2 ; γ g is a coefficient related to the grouting condition of the wall, for the masonry shear wall with partially grouted prestressed reinforcement , otherwise ; f' m is the standard value of compressive strength of masonry, in MPa; M n is the flexural capacity, in MPa.

7. The method of claim 1, wherein In step S5, the maximum applied stress of the prestressed steel bar shall not exceed 0.8 times the specified tensile strength of the prestressed steel bar and 0.94 times the specified yield strength of the prestressed steel bar; after the prestress is transmitted to the masonry shear wall, the stress in the prestress shall not exceed 0.82 times the yield strength and 0.74 times the ultimate tensile force; when the prestress is applied, the prestress at the anchorage device and the connector shall not exceed 0.78 times the yield strength and 0.7 times the ultimate stress.

8. The design method of claim 1, wherein, In step S6, according to the calculation results of steps S3-S5, the arrangement mode of the prestressed steel bar in the wall body is determined in combination with the structural stress characteristics and the prestress distribution, the arrangement mode including the number, the spacing, the tension end and the fixed end position; the selection of the prestressed steel bar needs to comprehensively consider the strength grade, the relaxation performance and the fatigue performance, the low-relaxation steel strand with a standard tensile strength not less than 1860MPa and a 1000h relaxation rate not greater than 2.5% is preferentially selected, and the over-tensioning ratio is determined according to the prestress loss value, but the over-tensioning value shall not exceed the maximum tension control stress limit value of the standard value of the prestressed steel bar strength not more than 75%.

9. A prestressed reinforced masonry shear wall, characterized by, The prestressed reinforced masonry shear wall comprises a prefabricated hollow block unit, a prestressed steel bar, a construction steel bar, a core concrete and an anchoring device of the prestressed steel bar; the prefabricated hollow block unit comprises a concrete hollow block, an aerated concrete block and a fly ash block, and the block has a hole; the prestressed steel bar is arranged in the hole of the block in the height direction of the shear wall, and both ends are provided with the anchoring device; the construction steel bar comprises a horizontally distributed construction steel bar and a vertically distributed construction steel bar, the horizontally distributed construction steel bar is arranged in the horizontal mortar joint of the block, and the vertically distributed construction steel bar is located in the hole of the block; the prestressed reinforced masonry shear wall is obtained by the design method of any one of claims 1-8.

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