Prestressed reinforced masonry shear wall and design method thereof

Abstract

The invention 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-layer shear wall structure, consumption of steel bars can be reduced, meanwhile, the self-resetting performance of the structure is effectively improved under the action of a major earthquake, and therefore the anti-seismic performance of the structure is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building structure engineering, and in particular relates to a prestressed reinforced masonry shear wall and a design method thereof. Background Art

[0002] Earthquake resistance is one of the key performance characteristics that need to be considered in building structures. Ordinary reinforced concrete structures can no longer meet earthquake resistance requirements, especially those of multi-story buildings. Under normal use and small earthquakes, ordinary reinforced concrete structures rely on ordinary steel bars and masonry to work together, but the brittle characteristics of masonry materials can easily cause walls to crack, and the cracks are difficult to control, which not only affects the durability of the structure, but may also cause functional problems such as leakage. During moderate and large earthquakes, although ordinary reinforced concrete structures can dissipate part of the seismic energy through plastic deformation, the residual deformation after the wall is damaged is large, and it is difficult to self-reset, resulting in degradation of stiffness and bearing capacity, and may even cause the risk of progressive collapse due to accumulated damage.

[0003] In the multi-story building sector, reinforced masonry shear wall structures are widely used due to their excellent load-bearing capacity, convenient construction, and economical construction costs. They have become a common form of civil construction, including residential and office buildings. However, traditional reinforced masonry shear walls have inherent shortcomings in terms of seismic performance, which limits their adoption in earthquake-prone areas. Due to performance limitations, traditional reinforced masonry shear walls require a large amount of steel for seismic design, which increases material costs and construction difficulty, contrary to the green and low-carbon development trend of the industry.

[0004] Existing earthquake-resistant design methods also have technical challenges. Current standards primarily ensure safety through measures such as limiting building heights and aspect ratios, installing seismic joints, and increasing material strength. However, these measures fail to fundamentally address the brittle failure of masonry structures, and post-earthquake repairs are costly and time-consuming.

[0005] With the advancement of urbanization and the improvement of seismic fortification standards, the seismic safety requirements for masonry buildings are becoming increasingly stringent. Particularly in earthquake-prone areas, the post-earthquake residual deformation and difficulty in repairing traditional reinforced masonry shear walls have hindered their widespread adoption. The construction industry urgently needs to reduce steel consumption and improve construction efficiency. Against this backdrop, the development of new reinforced masonry shear wall structures that combine excellent load-bearing capacity, seismic performance, and economic advantages has become a key approach to addressing the seismic challenges of multi-story masonry buildings and promoting the development of green buildings. Summary of the Invention

[0006] The present application is based on the discovery and understanding of the inventors of the following facts and problems: although prestressing technology is maturely applied in concrete structures, there is a technical gap in reinforced masonry shear wall structures, the reinforced masonry shear wall will go through 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 lead to 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 masonry and meet the differentiated design under different seismic actions is still a problem in the industry.

[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: S1. According to the importance of the building, the use function, and the seismic fortification intensity, the seismic performance target of the prestressed reinforced masonry shear wall is determined, and the seismic performance level is set; 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; 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; 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; S5. The ultimate bearing capacity of the prestressed reinforced masonry shear wall is calculated 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, 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; the selection and arrangement of prestressed reinforcement are carried out according to the calculation results of steps S3, S4 and S5; S7. The anchoring device of the prestressed reinforcement is determined, and the design of the prestressed reinforced masonry shear wall is completed.

[0009] The design method of the embodiment of the present application has the advantages and technical effects that: (1) Compared with the traditional technical solution, the design method of the prestressed reinforced masonry shear wall provided by the embodiment of the present application provides an innovative solution for the development of multi-story masonry buildings. By introducing prestressed reinforcement technology, the design method successfully builds a new type of masonry shear wall structure system, providing a solid technical guarantee for the safe application of multi-story masonry buildings under complex geological conditions.

[0010] (2) The core innovation of the design method of the prestressed reinforced masonry shear wall provided by the embodiment of the present application is that by reasonably configuring prestressed steel bars, core concrete and structural steel bars, the masonry shear wall can achieve bearing capacity performance and seismic performance comparable to concrete shear walls.

[0011] (3) The design method of the prestressed reinforced masonry shear wall provided by the embodiment of the present application optimizes the configuration of steel bars to reduce material consumption, providing an innovative solution for the seismic design of masonry shear wall structures, effectively improving the bearing performance and lateral resistance of masonry shear walls at different load stages, and enhancing the overall seismic performance of the building.

[0012] 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 force steel bars, structural steel bars and prestressed steel bars.

[0013] Optionally, in step S3, the combination of multiple loads includes a combination 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.

[0014] Optionally, 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 requirements of axial compression resistance and lateral bending resistance, controlling horizontal displacement and vertical displacement to ensure the overall stability of the structure and the use function, and at the same time, adjusting the prestressed steel bar tension stress and steel bar arrangement to optimize the performance of the wall.

[0015] Optionally, in step S4, For the wall body bearing axial compression, it needs to meet ; When the of the wall body is not greater than 99,

[0016] When the wall height is greater than 99,

[0017]

[0018]

[0019] 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 flexural stress of the masonry, F a is the design value of the axial compressive strength of the masonry, F b is the design value of the flexural compressive strength 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.

[0020] Optionally, in step S4, the design flexural strength is taken as the theoretical flexural strength M n multiplied by a strength reduction coefficient Ø, and Ø = 0.8; For a cross section B with uniform width over the depth of the compression zone, the depth of the equivalent compressive stress block is a , ; wherein, a is the equivalent compression zone height, in mm; f ps is the ultimate state 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 structural reinforcement, in mm 2 ; f y is the standard value of the yield strength of the steel and anchor, in MPa; P u is the design value of the axial load, in N; f'm is the standard value of compressive strength of masonry, unit: MPa; b is the cross-sectional width, unit: mm; strength reduction coefficient , = 0.8; moment strength of prestressed reinforced masonry shear wall with width b M n is calculated by the following formula: , wherein, d is the effective height of cross-section, unit: mm, M n is the flexural capacity, unit: MPa; 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.

[0021] Optionally, in step S4, for the prestressed reinforced masonry shear wall, the effective prestress of prestressed reinforcement f se is calculated by the following formula: ; wherein, f se is the effective prestress of prestressed reinforcement; E ps is the elastic modulus of prestressed reinforcement; is the net length of prestressed reinforcement; f ps is the ultimate state stress of prestressed reinforcement, unit: MPa; A ps is the cross-sectional area of prestressed reinforcement, unit: mm 2 ; f' m is the standard value of compressive strength of masonry, unit: MPa.

[0022] Optionally, in step S4, the shear strength of prestressed reinforced masonry shear wall is calculated by adopting the following a), b), c) formulas, and taking the minimum value, a) ; b) ; c) ; if , ; if , ; wherein V n is the design value of shear force, in N, V ns is the design value of shear force of stirrup, in N, V nm is the design value of shear force of masonry, in N, A nv is the net shear area, in 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 .

[0023] Optionally, 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 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; during the application of the prestress, 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.

[0024] Optionally, in step S6, according to the calculation results of steps S3-S5, the arrangement mode of the prestressed steel bar in the wall is determined in combination with the structural stress characteristics and the prestress distribution, and the arrangement mode includes the number, the spacing, the position of the tension end and the fixed end, etc.; the selection of the prestressed steel bar needs to comprehensively consider the strength grade, the relaxation performance and the fatigue performance, and the low-relaxation steel strand with a standard value of 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 shall not exceed the maximum tension control stress limit value of the specification, which is not more than 75% of the standard value of the strength of the prestressed steel bar.

[0025] In a second aspect, the embodiments of the present application provide a prestressed reinforced masonry shear wall, which comprises a prefabricated hollow block unit, a prestressed steel bar, a construction steel bar, a core grouting 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 of the prestressed steel bar 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 the first aspect.

[0026] The prestressed reinforced masonry shear wall of the embodiments of the present application has the following advantages and technical effects: (1) The prestressed reinforced masonry shear wall of the embodiment of the present application can enhance the integrity of the wall under normal use and small earthquakes, and inhibit the generation of cracks. Under medium and large earthquakes, the prestress is used to achieve self-resetting and reduce residual deformation, so as to ensure that the shear wall has sufficient stiffness and bearing capacity, and can have good bearing performance and lateral resistance in different load stages, thereby improving the overall seismic performance of the structure.

[0027] (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 earthquakes, the cooperative deformation mechanism between the prestressed reinforcement and the masonry can effectively dissipate seismic energy and reduce the degree of structural damage. Second, the excellent deformation performance of the wall can maintain the 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

[0028] Figure 1 A structural schematic diagram of a prestressed reinforced masonry shear wall is shown. Figure 2 A structural schematic diagram of a prefabricated hollow block unit is shown. Explanation of reference signs: 1-prefabricated hollow block unit, 2-core concrete; 3-horizontal distribution reinforcement; 4-vertical distribution reinforcement; 5-prestressed reinforcement, 6-anchoring device. DETAILED DESCRIPTION

[0029] The embodiments of the present application will be 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.

[0030] In a first aspect, the embodiment of the present application provides a design method of a prestressed reinforced masonry shear wall suitable for a multi-story shear wall structure, comprising the following steps: S1. According to the importance of the building, the core use function and the seismic fortification intensity of the region, etc., the seismic performance target of the shear wall is accurately determined, and the appropriate seismic performance level is set.

[0031] 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.

[0032] 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.

[0033] The specific process is as follows. First, the key dimensions of the wall, such as length, height, and thickness, are preliminarily determined. The setting of wall dimensions needs to consider three factors: first, the architectural space use requirements to avoid unreasonable compression of internal use space due to wall dimensions; 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 dimensions with the block module and reduce on-site cutting operations. Then, the type and strength grade of the block, such as concrete hollow block or aerated concrete block, are determined, and the appropriate core concrete mix proportion is selected. 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. Based on the stress analysis of the wall, the vertical and horizontal arrangement methods of the structural steel in the wall, the arrangement 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.

[0034] 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 length, height, and thickness, replacing higher strength grade steel types, or adjusting the prestressed tension control stress, etc. After adjustment, the bearing capacity calculation process is executed again until the results meet the design requirements.

[0035] 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.

[0036] 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.

[0037] (1) For the wall subjected to axial compression, the following design method should be used: ; When the wall's is not greater than 99,

[0038] When the wall's is greater than 99,

[0039]

[0040]

[0041] where, h is the wall height, r is the radius of gyration, e is the eccentricity, f a is the masonry axial compressive stress, f b is the masonry axial bending stress, F a is the masonry axial compressive strength design value, F b is the masonry bending compressive strength design value, f' m is the masonry compressive strength standard value, unit: MPa, P is the axial load, Pe The elastic yield critical load of the axial compression member, E m The elastic modulus of the masonry, I n The moment of inertia of the net section.

[0042] For prestressed reinforced masonry shear walls with transverse unrestrained reinforcement, the prestress of the prestressed reinforcement P ps Should be included in the calculation of the axial load P .

[0043] For prestressed reinforced masonry shear walls with transverse restrained reinforcement, the prestress P P ps Should not be considered when calculating the axial load

[0044] (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.

[0045] For cross-section B with uniform width in the depth of the compression zone, the depth of the equivalent compressive stress block a Should be determined by the following formula: ; Where, a The equivalent compression zone height is mm, f ps The prestressed reinforcement ultimate state stress is MPa, A ps The prestressed reinforcement cross-sectional area is mm 2 , A s The longitudinal reinforcement cross-sectional area is mm 2 , f y The yield strength standard value of steel bars and anchors is MPa, P u The design value of the axial load is N, f' m The compressive strength standard value of the masonry is MPa, b ​b is the width of the section in mm.

[0046] For the flexural strength of prestressed reinforced masonry shear walls of width b M n The following formula shall be used: ; Where, d b is the effective depth of the section in mm, M n M is the flexural strength, also known as the flexural capacity, in MPa.

[0047] Distance d The following formula shall be used to calculate the distance from the centerline of the tendon to the actual compression face of the member. For prestressed tendons and 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.

[0048] When tendons are not placed in the center of the wall, the following formula shall be used to calculate the distance from the centerline of the tendon to the actual compression face of the member for each direction of out-of-plane bending d .

[0049] For walls with prestressed reinforcement, the following formula shall be used to calculate the effective prestress of the prestressed reinforcement f ps : ; Where, f se P is the effective prestress of the prestressed reinforcement, E ps E is the modulus of elasticity of the prestressed reinforcement, L is the net length of the prestressed reinforcement, f ps f is the prestressed reinforcement stress at ultimate limit state in MPa, A ps A is the cross-sectional area of the prestressed reinforcement in mm 2 , f' m f is the standard compressive strength of the masonry in MPa.

[0050] (3) The shear strength of prestressed reinforced masonry shear walls shall be calculated using the following a), b), and c) formulas, and the minimum value shall be taken.

[0051] a) ; b) ; c) ; in V n Not exceed the following values: like , ; like , ; For partially grouted prestressed reinforced masonry shear walls ,otherwise ; V n is the shear force design value, in N, V ns is the design value of stirrup shear force, in N, V nm is the design value of masonry shear force, in N, A nv is the net shear area in m 2 .

[0052] S5. Under moderate and major earthquakes, the ultimate bearing capacity calculations for prestressed reinforced masonry shear walls must strictly meet the performance requirements of the Code for Seismic Design of Buildings for the corresponding earthquake levels.

[0053] The calculation needs to take into account vertical loads such as the deadweight of the structure, live loads on the floor, and horizontal loads under moderate and major earthquakes. By analyzing the internal forces and deformations of the wall under these load combinations, ensure that the performance of the wall structure meets the standards and meets the requirements for normal use of the building. For bearing capacity requirements, calculate the axial compressive bearing capacity and shear bearing capacity as well as the lateral bending capacity of the wall, and the mechanical stability of the wall structure under load. For deformation control, calculate the horizontal and vertical displacements of the wall to ensure that the deformation is within the limit to avoid affecting the overall stability and usability of the structure. For the specific calculation formulas involved, please refer to the calculation formula in step S4.

[0054] The maximum applied stress of prestressed steel bars shall not exceed 0.8 times the specified tensile strength of the prestressed steel bars and 0.94 times the specified yield strength of the prestressed steel bars; 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 prestressing is applied, the prestress at the anchors and connectors shall not exceed 0.78 times the yield strength and 0.7 times the ultimate stress.

[0055] The calculation needs to focus on the plastic deformation capacity, stiffness degradation law and ultimate limit bearing state of the wall under the action of reciprocating loads, to ensure that the damage to the wall structure is controllable during moderate earthquakes and that it does not collapse during major earthquakes.

[0056] If the calculation result does not meet the ultimate bearing capacity requirement of the Code for Seismic Design of Buildings, edge member restraining hoops can be added to enhance the restraining capacity of the edge region of the wall, improve the strength grade of the core concrete, and enhance the overall stress performance of the wall by optimizing the mix proportion to improve the compressive strength and ductility of the core concrete, adjusting the arrangement of the prestressed steel, and further exerting the self-centering effect of the prestress to 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 target under the action of moderate earthquakes and major earthquakes is met.

[0057] S6. Selecting and arranging the prestressed steel according to the calculation result.

[0058] If the calculation result of any one of steps S3, S4, and S5 does not meet the design requirement, the design parameters and arrangement scheme of the prestressed reinforced masonry shear wall are adjusted and recalculated until the calculation result meets the design requirement (i.e., the relevant building structure design standards such as the Code for Seismic Design of Buildings and the Code for Design of Masonry Structures). After the calculation result of the previous steps meets the design requirement, the arrangement of the prestressed steel in the wall is determined according to the calculation result of the previous steps, the stress characteristics of the structure, and the calculated prestress distribution, including the number, spacing, and positions of the tension end and fixed end of the prestressed steel. The selection of the prestressed steel needs to consider indicators such as strength grade, relaxation performance, and fatigue performance.

[0059] Low-relaxation steel strands with a standard tensile strength not less than 1860 MPa are preferentially 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 steel should be combined with the stress characteristics of the wall and the seismic performance requirements. The prestressed steel is arranged reasonably in the tensile and compressive 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 requirement of the prestressed steel 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 steel 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 proportion of the prestressed steel 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 steel. Through the above selection and arrangement, the mechanical properties of the prestressed steel can be fully exerted to ensure that the wall works cooperatively with the blocks and core concrete in each stress stage and improve the overall seismic performance of the structure.

[0060] S7. Selecting a reliable prestressed steel anchoring device to complete the design of the prestressed reinforced masonry shear wall.

[0061] For the anchoring of prestressed reinforcement in 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 grouted in the masonry shall not be less than 0.95 to ensure that the prestress is effectively transmitted to the wall; and the fatigue performance test shall be passed to meet the durability requirements under repeated loads in seismic design to avoid prestress loss due to anchoring failure. Adhesive anchoring is often used in pre-tensioning method or part of non-tensioning end in post-tensioning method. The length of adhesive anchoring shall 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 prestress. Through the reasonable selection of the above anchoring methods, the prestressed reinforcement and the wall can work together to ultimately complete the overall design of the prestressed reinforced masonry shear wall.

[0062] 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 reinforcement 5, a construction reinforcement, a core grouting concrete 2 and an anchoring device 6 of the prestressed reinforcement; the prefabricated hollow block unit 1 comprises load-bearing blocks such as concrete hollow blocks, aerated concrete blocks, fly ash blocks, etc., and the blocks have holes; the prestressed reinforcement 5 is 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 reinforcement comprises horizontally distributed construction reinforcement 3 and vertically distributed construction reinforcement 4, the horizontally distributed construction reinforcement 3 is arranged in the horizontal mortar joint of the blocks, and the vertically distributed construction reinforcement 4 is located in the holes of the blocks; the prestressed reinforced masonry shear wall is obtained by the design method of the first aspect.

[0063] The present application will be described in detail below with reference to the embodiments and drawings.

[0064] A design method of a prestressed reinforced masonry shear wall suitable for a multi-story shear wall structure, comprising the following steps: 1. Precisely determine the overall structural performance target according to the use function of the building, the safety standard and the site conditions and other factors. This target needs to be established by considering various requirements of the building in the normal use process and the safety requirements in the possible extreme situations (such as earthquake, wind, etc.). Then, the ordinary structure design is carried out according to the building scheme, which needs to follow the relevant building design specifications and mechanical principles to ensure the preliminary rationality and feasibility of the structure.

[0065] 2. Consider the spatial layout, force characteristics, and seismic requirements of the building, accurately determine the specific location of prestressed reinforced masonry shear walls in the building. These positions are usually the key parts of the structure with more concentrated stress and greater influence on the overall stability. At the same time, according to the size, height, load size and other conditions of the building, reasonably determine the size of the prestressed reinforced masonry shear wall, including the length, thickness and height of the wall, so as to ensure that the wall can effectively bear and transfer the load.

[0066] 3. According to the seismic fortification intensity and site category of the building location, determine the seismic performance requirements of the building. This includes specific indicators for the deformation capacity, energy dissipation capacity, and collapse resistance of the structure under earthquake action. At the same time, combined with the use function and design standard of the building, determine the bearing capacity design requirements of the structure, including the bearing capacity requirements of vertical loads (such as self-weight, live load, etc.) and horizontal loads (such as wind load, earthquake action, etc.). Then, according to the relevant building codes of the state, the load combination under the most unfavorable working condition is calculated to determine the load combination that the structure bears.

[0067] 4. Determine the required prestress on the prestressed steel bar. First, determine the yield strength f py and the specified tensile strength f pu of the prestressed steel bar. To ensure the safety and reliability of the structure, the required prestress must meet certain limitations, i.e. 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 steel bar must also be limited, which must not exceed 0.82 f py or 0.74 f pu ; during the prestressing process, the prestress at the anchor and connector must not exceed 0.78 f py or 0.7 f pu . Through the above conditions, and combined with the actual required prestress of the shear wall, the most suitable type of prestressed steel bar is selected from the existing types on the market. In addition, due to the influence of various factors in actual engineering, such as the elastic shrinkage of the masonry, stress loss during anchoring, and thermal effects, etc., these factors need to be considered comprehensively, and the effective stress of the prestressed steel bar f se is obtained through reasonable calculation method.

[0068] 5. For the wall subjected to axial compression, the following requirements should 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, which is controlled by specific stress calculation and proportional relationship, i.e. ; and .

[0069] This limit condition is to prevent the wall from being damaged under excessive axial load and to ensure that the wall has sufficient safety reserve when subjected to axial compression.

[0070] For the geometric parameters of the wall h / r (where h is the effective height of the wall, and r is the radius of rotation), when ; when h / r is greater than 99, .

[0071] to adapt to the stress characteristics of walls with different geometric characteristics. Another compressive stress F b is determined according to the standard compressive strength of the masonry and a fixed proportional relationship.

[0072] .

[0073] The calculation of the bending load P e needs to consider multiple factors such as the elastic modulus of the wall, the moment of inertia, the height of the wall, and the eccentricity.

[0074] .

[0075] 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. When determining the design bending moment strength of the wall, the theoretical bending moment strength M n 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 and the differences in construction quality, to ensure the safety of the structure in actual use. For a cross-section with uniform width in the depth of the compression zone B , the depth of the equivalent compressive stress block a needs to be calculated through a specific formula.

[0076] .

[0077] The formula comprehensively considers the prestress applied by the prestressed steel, the area of the prestressed steel, the effective sectional steel area, the yield strength standard value of the steel and anchorage, the design value of the axial load, the compressive strength standard value of the masonry, and the sectional width, so as to accurately determine the stress distribution of the compression zone.

[0078] For the prestressed reinforced masonry shear wall with a width of b, the moment strength M n The value needs to be calculated by the following formula.

[0079]

[0080] The formula comprehensively considers the prestress applied by the prestressed steel, the area of the prestressed steel, the effective sectional steel 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 tendon to the compression surface of the component. The distance d should be accurately calculated as the actual distance from the center line of the steel tendon to the compression surface of the component. For the prestressed steel tendon and the out-of-plane loaded wall, in order to ensure the stress performance and safety of the wall, d The value should not exceed the thickness of the surface shell plus half the diameter of the steel tendon plus 0.95 cm. When the steel tendon is not placed at the center position of the wall, the value of each direction of the out-of-plane bending needs to be calculated respectively to ensure that the wall can meet the design requirements under different stress conditions. d

[0081] 7. For the prestressed reinforced masonry shear wall, the prestress applied by the prestressed steel f ps The value needs to be calculated by the following formula.

[0082]

[0083] The formula comprehensively considers the effective stress of the prestressed steel f se , the elastic modulus of the prestressed steel, the actual distance from the center line of the steel tendon to the compression surface of the component, the geometric size of the wall, and the load borne by the wall, so as to accurately determine the actual stress state of the prestressed steel under different working conditions.

[0084] For the prestressed reinforced masonry shear wall, the shear strength needs to be calculated by the following a), b), and c) three formulas.

[0085] a) ; b) ; c) ; ​The minimum value is selected from the calculation results of the above three different calculation formulas as the shear strength of the wall f ps The calculation formulas of the compressive strength standard value of the masonry and the net shear area, etc. are considered in the calculation formulas of the wall shear strength, so as to ensure that the wall has sufficient safety reserve when bearing shear force.

[0086] The wall shear strength calculation formula comprehensively considers the shear strength of the block, the shear strength provided by the shear reinforcement, and a coefficient related to the grouting condition of the wall gamma g At the same time, the shear strength of the wall is also limited, and different upper limit values are set according to the different ratios of the bending moment strength of the wall to the product of the shear force and the effective height of the wall.

[0087] If , ; If , ; For the partially grouted prestressed reinforced masonry shear wall, gamma g the value is 0.75; for other cases, gamma g the value is 1.

[0088] 8. The prestressed reinforcement 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 reinforcement on the masonry, using the bearing capacity of the masonry to fix the prestressed reinforcement; or placing the prestressed reinforcement in the mechanical anchoring device inside the concrete end block or fully grouted masonry, and ensuring the reliable connection of the prestressed reinforcement 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 reinforcement in the structure. The selection and application of these anchoring methods need to be reasonably determined according to the specific engineering conditions and design requirements, so as to ensure that the prestressed reinforcement can effectively play its role and improve the overall performance and safety of the structure.

[0089] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the terminology "comprising" is used in the disclosure as comprising but not limited to, that is, it is open-ended and does not exclude the presence of additional features, structures, materials, or characteristics.

[0090] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above-described embodiments are exemplary, and are not to be interpreted as limiting the present disclosure, and the ordinary skilled person in the art can make changes, modifications, replacements, and variations to the above-described embodiments within the scope of the present disclosure.

Claims

1. A design method for prestressed reinforced masonry shear wall, characterized in that: The following steps are involved: S1. Determine the seismic performance targets and set seismic performance levels for prestressed reinforced masonry shear walls based on the building's importance, function, and seismic fortification intensity. S2. Determine the design parameters and layout of the prestressed reinforced masonry shear walls based on the seismic performance objectives and levels, in conjunction 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 layout of the prestressed reinforced masonry shear wall, so that the calculation results meet 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 minor earthquakes, so that the calculation results meet the bearing capacity design requirements under normal use conditions and minor earthquakes; S5. Calculate the ultimate bearing capacity of prestressed reinforced masonry shear walls under moderate and severe earthquakes, ensuring that the calculation results meet the bearing capacity design requirements under moderate and severe earthquakes. S6. If the calculation results of steps S3, S4, and S5 do not meet the design requirements, the design parameters and layout of the prestressed reinforced masonry shear wall are adjusted and recalculated until the calculation results meet the design requirements; the selection and layout of prestressed steel bars are performed 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 according to claim 1, characterized in that: In step S2, the design parameters and layout of the prestressed reinforced masonry shear wall are determined, specifically including: preliminary determination of the wall size, length, height, thickness, block type and strength grade, core concrete mix ratio, and preliminary determination of the specifications, quantity, and layout position of the load-bearing steel bars, structural steel bars, and prestressed steel bars.

3. The design method according to claim 1, characterized in that: In step S3, the multi-load combination includes a combination of vertical loads and horizontal loads, wherein the vertical loads include the deadweight of the structure and the live load of the floor, and the horizontal loads include wind loads and earthquake loads.

4. The design method according to claim 1, characterized in that: Step S4 specifically includes the following steps: under normal use conditions and small earthquakes, considering the vertical load and the horizontal load under the action of small earthquakes, where the vertical load includes the deadweight of the structure and the live load of the floor, calculating the internal force and deformation of the wall, ensuring that the wall meets the normal use requirements, including meeting the axial compressive strength and lateral bending strength requirements, controlling the horizontal and vertical displacements to ensure the overall stability and use function of the structure, and optimizing the wall performance by adjusting the prestressed steel bar tensioning stress and steel bar arrangement.

5. The design method according to claim 1 or 4, characterized in that: In step S4, For walls subjected to axial compression, ; When the wall No more than 99 hours, When the wall When it is greater than 99, in, h is the wall height, 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 bending stress of the masonry, F a is the design value of the axial compressive strength of masonry, F b is the design value of masonry flexural compressive strength, f' m is the standard value of compressive strength of masonry, in MPa. P is the axial load, P e is the elastic yield critical load of the axially compressed member, E m is the elastic modulus of masonry, I n is the moment of inertia of the net section.

6. The design method according to claim 1 or 4, characterized in that: In step S4, the design moment strength is taken as the theoretical moment strength M n Multiply by the strength reduction factor Ø, Ø=0.8; For a cross section B with uniform width across the depth of the compression zone, the depth of the equivalent compressive stress block is a , ； in, a is the height of the equivalent compression zone, in mm; f ps is the ultimate stress of the prestressed steel bar, in MPa; A ps is the cross-sectional area of ​​the prestressed steel bar, in mm 2 ; A s is the cross-sectional area of ​​the longitudinal structural steel bar, in mm 2 ; f y is the standard value of yield strength of steel bars and anchor bolts, in MPa; P u is the design value of the axial load, in N; f' m is the standard value of compressive strength of masonry, in MPa; b is the cross-section width, in mm; strength reduction factor Ø, Ø=0.8; Bending moment strength of prestressed reinforced masonry shear wall with width b M n Calculated by the following formula: ， in, d is the effective height of the section, in mm; M n is the bending bearing capacity, in MPa; d should be calculated as the actual distance from the centerline of the tendon to the compression face of the member, in cm. For walls prestressed with tendons and loaded out-of-plane, d should not exceed the face shell thickness plus half the tendon diameter plus 0.95 cm. When the tendon is not placed in the center of the wall, d should be calculated for each direction of out-of-plane bending. In step S4, for prestressed reinforced masonry shear walls, the effective prestressing force of the prestressed steel bars is f se Calculated by the following formula: ； in, f se is the effective prestress of the prestressed steel bars, E ps is the elastic modulus of the prestressed steel bar, is the net length of the prestressed steel bar, f ps is the ultimate stress of the prestressed steel bar, in MPa; A ps is the cross-sectional area of ​​the prestressed steel bar, in mm 2 ; f' m It is the standard value of compressive strength of masonry, in MPa.

7. The design method according to claim 1 or 4, characterized in that: In step S4, the shear strength of the prestressed reinforced masonry shear wall is calculated using the following formulas a), b), and c), and the minimum value is taken. a） ； b） ； c） ； like , ; like , ; Among them, V n is the shear force design value, in N, V ns is the design value of stirrup shear force, in N, V nm is the design value of masonry shear force, in N, A nv is the net shear area in m 2 ; γ g is a coefficient related to the wall grouting condition. For partially grouting prestressed reinforced masonry shear walls, ,otherwise .

8. The design method according to claim 1, characterized in that: In step S5, the maximum applied stress of the prestressed steel bars shall not exceed 0.8 times the specified tensile strength of the prestressed steel bars and 0.94 times the specified yield strength of the prestressed steel bars; 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 applying prestress, the prestress at the anchors and connectors shall not exceed 0.78 times the yield strength and 0.7 times the ultimate stress.

9. The design method according to claim 1, characterized in that: In step S6, based on the calculation results of steps S3 to S5, combined with the structural stress characteristics and prestress distribution, the arrangement of prestressed steel bars in the wall is determined, including the number, spacing, tensioning end and fixed end positions, etc.; the selection of prestressed steel bars needs to comprehensively consider the strength grade, relaxation performance, and fatigue performance, and low-relaxation steel strands with a tensile strength standard value of not less than 1860 MPa and a 1000h relaxation rate of not more than 2.5% are preferred. The over-tension ratio is determined based on the prestress loss value, but the over-tension value shall not exceed the maximum tension control stress limit specified in the specification and shall not exceed 75% of the standard value of the prestressed steel bar strength.

10. A prestressed reinforced masonry shear wall, characterized in that: The prestressed reinforced masonry shear wall includes prefabricated hollow block units, prestressed steel bars, structural steel bars, core concrete and anchoring devices for the prestressed steel bars; the prefabricated hollow block units include load-bearing blocks such as concrete hollow blocks, aerated concrete blocks, fly ash blocks, etc., and the blocks have holes; the prestressed steel bars are arranged in the holes of the blocks along the height direction of the shear wall, and anchoring devices are provided at both ends; the structural steel bars include horizontally distributed structural steel bars and vertically distributed structural steel bars, the horizontally distributed structural steel bars are arranged in the horizontal mortar joints of the blocks, and the vertically distributed structural steel bars are located in the holes of the blocks; the prestressed reinforced masonry shear wall is obtained by the design method described in any one of claims 1 to 9.

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