GB 50702-2011 English PDF
Basic dataStandard ID: GB 50702-2011 (GB50702-2011)Description (Translated English): Code for design of strengthening masonry structures Sector / Industry: National Standard Classification of Chinese Standard: P24 Classification of International Standard: 91.080.30 Word Count Estimation: 140,171 Date of Issue: 2011-07-26 Date of Implementation: 2012-08-01 Quoted Standard: GB 50003; GB 50009; GB 50010; GB 50011; GB 50016; GB 50017; GB 50023; GB 50144; GB 50210; GB 50292; GB 50367; GB 50550; GB 175; GB 199; GB/T 700; GB 1499.1; GB 1499.2; GB 1499.3; GB/T 1591; GB/T 5117; GB/T 5118; GB/T 9914.3; GB 13014; GB/T 15393; JGJ 18; JGJ 52; JGJ 63; JGJ 70; JGJ 81; JGJ 114; JGJ 116; JG/T 3064 Regulation (derived from): Bulletin of the Ministry of Housing and Urban No. 1095 Issuing agency(ies): Ministry of Housing and Urban-Rural Development of the People's Republic of China; General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Summary: This Chinese standard applies to housing and the general design of structures reinforced masonry structures. GB 50702-2011: Code for design of strengthening masonry structures---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.1 General 1.0.1 This specification is formulated in order to make the reinforcement of masonry structures reliable in technology, safe and applicable, economical and reasonable, and ensure quality. 1.0.2 This code is applicable to the reinforcement design of masonry structures of houses and general structures. 1.0.3 Before the masonry structure is strengthened, the reliability appraisal shall be carried out according to the relevant provisions of the current national standards "Industrial Building Reliability Appraisal Standard" GB 50144 and "Civil Building Reliability Appraisal Standard" GB 50292 according to different building types. When it is carried out in combination with seismic reinforcement, the seismic capacity appraisal should be carried out according to the relevant provisions of the current national standard "Building Seismic Appraisal Standard" GB 50023. 1.0.4 The reinforcement design of masonry structures shall not only comply with the provisions of this code, but also comply with the relevant current national standards. 2 Terms and symbols 2.1 Terminology 2.1.1 Strengthening of masonry structures Measures such as reinforcement, partial replacement, or adjustment of internal force shall be taken for masonry structures, components and related parts that are not reliable enough or required to be improved by the owner, so that they have the safety, durability and applicability required by the current design specifications and the owner's requirements. sex. 2.1.2 Existing structure member The original components before reinforcement. 2.1.3 important structure member A component whose failure by itself will affect or endanger the safe operation of the load-bearing structural system. 2.1.4 general structure member Components other than important components. 2.1.5 composite cement mortar Mortar with cement and high-performance mineral admixture as the main component, and mixed with admixtures and short fine fibers. 2.1.6 polymer modified cement mortar High-strength cement mortar mixed with modified epoxy emulsion or other modified copolymer emulsion. Polymer-modified cement mortars for load-bearing structures should significantly improve their ability to anchor steel bars and bond substrates such as concrete and masonry. 2.1.7 Steel reinforcement mesh It is a mesh welded by ordinary hot-rolled ribbed steel bars or cold-rolled ribbed steel bars. 2.1.8 fiber reinforced polymer High-strength continuous fibers are arranged according to certain rules, and are impregnated with adhesives, bonded and cured to form composite materials with fiber-reinforced effects, commonly known as fiber composites. 2.1.9 Strength utilization factor of material Consider the calculation coefficient introduced by the fact that the strength of the reinforcement material cannot be fully utilized under the condition of secondary stress. 2.1.10 external layer strengthening A reinforcement method that increases the bearing capacity and stiffness of the original component by adding a reinforced concrete surface layer or a reinforced mesh mortar surface layer. 2.1.11 Outsourcing steel reinforcement method sectional steel strengthening The reinforcement method in which the masonry columns are welded with shaped steel limbs and panels, and the external forces are distributed according to the respective stiffness ratios, is also called dry-type outsourcing steel reinforcement method. 2.1.12 external prestressed strut strengthening method By tightening the transverse screw device, preloading is applied to two pairs of angle steel braces with cutouts and bent shapes, so as to release the load borne by the masonry column to the braces. 2.1.13 buttress column reinforcement method counterfort masonry column strengthening The reinforcement method of thickening the local wall at intervals along the length of the masonry wall to form a wall with stacked stiffeners. 2.1.14 masonry crack repairing method masonry crack repairing A repair or repair performed to seal cracks in masonry or to restore the integrity of cracked masonry. 2.2 Symbols 2.2.1 Material properties Em—Elastic modulus of original component masonry; Ea—the elastic modulus of newly added steel; Ef—elastic modulus of newly added fiber composite; fmo, f—respectively design values of compressive strength of original masonry and new masonry; fc—design value of axial compressive strength of newly added concrete; fy, f'y—respectively design values of tensile strength and compressive strength of newly added reinforcement; ff—new design value of tensile strength of fiber composite material. 2.2.2 Action effect and bearing capacity N—design value of axial pressure after member reinforcement; M—Design value of bending moment after component strengthening; V—Design value of shear force after strengthening of member; σs—tensile stress of steel bar. 2.2.3 Geometric parameters Amo—the cross-sectional area of the original member masonry; Ac - newly added concrete cross-sectional area; As—the cross-sectional area of newly added reinforcement; Aa—the total cross-sectional area of newly added section steel (angle steel); h—the section height of the member after reinforcement; ho—the effective height of the section after reinforcement; b—the rectangular section width of the original member; Imo—the section moment of inertia of the original member; Ia—steel frame section moment of inertia; Ho—calculated height of member; hT—converted thickness of wall section with pilasters. 2.2.4 Calculation coefficients β—height-thickness ratio of masonry components; αc—additional concrete strength utilization factor; αs—additional reinforcement strength utilization factor; αf—fiber composite material participation work coefficient; αm—additional masonry strength utilization factor; —Stability factor of composite masonry members under axial compression; Km—the original masonry stiffness reduction coefficient; η—cooperative work coefficient; ρf—circumferential enclosure volume ratio. 3 Basic Regulations3.1 General provisions 3.1.1 When the masonry structure needs to be reinforced after the reliability appraisal, the reinforcement design shall be carried out by qualified professional and technical personnel in accordance with the provisions of this code and the requirements of the owner according to the appraisal conclusion and the requirements of the entrusting party. The scope of reinforcement design can be determined according to the whole building or an independent section, or according to the specified structure, component or connection, but the overall firmness of the structure should be considered, and energy saving and environment should be considered comprehensively. protection requirements. 3.1.2 In the reinforcement design, if it is found that the original masonry structure has no ring beams and structural columns, or there is no tie, anchorage and necessary support in the part involving the overall firmness of the structure, or the number of these structural measures is insufficient or improperly set, should be supplemented or modified in this reinforcement design. 3.1.3 The safety level of the reinforced masonry structure shall be agreed upon by the entrusting party and the designer according to the actual situation according to the severity of the structural damage consequences, the importance of the structure and the service life of the reinforced design. 3.1.4 For the reinforcement design of masonry structures, a scientific and reasonable plan should be selected according to the structural characteristics, and should be closely combined with the actual construction method, and effective measures should be taken to ensure that the newly added components and components are reliably connected to the original structure. Bond firmly with the original section to form a whole and work together; and avoid adverse effects on unreinforced parts, as well as related structures, components and foundations. 3.1.5 For damage to the original structure caused by high temperature, high humidity, low temperature, freeze-thaw, chemical corrosion, vibration, temperature stress, uneven foundation settlement and other influencing factors, effective prevention and control countermeasures should be put forward in the reinforcement design, and according to the design regulations governance and hardening in order. 3.1.6 The reinforcement design of masonry structures should comprehensively consider its technical and economic effects, and should not only avoid reinforcement of structures with poor repairability, but also avoid unnecessary demolition or replacement. Note. A structure with very poor repairability refers to a structure whose total reinforcement cost reaches more than 70% of the total cost of a new structure, but does not include cultural relic buildings and other buildings with historical or artistic value. 3.1.7 For masonry structures that may be tilted, unstable, excessively deformed or collapsed during the reinforcement process, effective temporary safety measures should be proposed in the reinforcement design documents, and the construction unit must be strictly implemented. 3.1.8 The reinforced design service life of masonry structures shall be determined according to the following principles. 1 The service life after structural strengthening shall be agreed upon by the owner and the design unit. 2 Under normal circumstances, it should be considered as 30 years; after the expiration, if the re-conducted reliability appraisal considers that the structure is working normally, its service life can still be extended. 3 For structures and components that are reinforced by glue or mixed with polymers, their working status should be checked regularly. The inspection interval can be determined by the design unit, but the first inspection time should not be later than 10 years. 3.1.9 Without technical appraisal or design permission, the use and environment of the reinforced masonry structure shall not be changed 3.2 Principles of Design Calculation 3.2.1 The structural analysis method used in the reinforcement design of masonry structures, in general, the linear elastic analysis method should be used to calculate the effect of the structure, and should comply with the relevant provisions of the current national standard "Code for Design of Masonry Structures" GB 50003. 3.2.2 When strengthening the masonry structure, the bearing capacity shall be designed and checked according to the following regulations, and the requirements for normal use functions shall be met. 1 The structural effect shall be verified by investigation or testing, and its standard value or representative value shall be determined according to the provisions and requirements of Appendix A of this code. 2 The action effect of reinforced structures and members shall be determined according to the following requirements. 1) The calculation graphics of the structure shall conform to its actual stress and structural conditions; 2) The combination of action effects, combined value coefficients, and sub-item coefficients of action should be determined according to the relevant provisions of the current national standard "Code for Building Structure Loads" GB 50009, and the factors caused by actual load eccentricity, structural deformation, and temperature effects should be considered. Additional internal force. 3 For the dimensions of structures and components, the actual measured values shall be used for the original parts; for the newly added parts, the nominal values given in the reinforcement design documents may be used. 4 The masonry strength grade of the original structure and components and the standard value of the tensile strength of the stressed steel bars shall be taken according to the following regulations. 1) When the original design documents are valid and there is no doubt that the structure has serious performance degradation, the original design value can be used; 2) When the structural reliability appraisal considers that on-site testing should be carried out again, the standard value estimated from the testing results shall be adopted. 5 The performance and quality of reinforcement materials shall comply with the provisions of Chapter 4 of this code; the standard value of its performance shall be determined in accordance with Article 3.2.3 of this code; the design value of its performance shall be adopted in accordance with the provisions of relevant chapters of this code. 6 When checking and calculating the bearing capacity of structures and components, the actual stress status of the original structure during reinforcement should be considered, including the characteristics of the strain lag of the reinforced part, and the degree of joint work between the reinforced part and the original structure. 4.2.3 In the masonry structure reinforcement project, it is strictly forbidden to use expired cement, damp cement, cement of mixed varieties, and cement without factory certificate or entry inspection. 4.2.4 When preparing concrete for structural reinforcement, the type and quality of the aggregate shall meet the following requirements. 1 Coarse aggregate should be hard and durable crushed stone or pebble. Its maximum particle size should meet the following requirements. 1) For on-site mixed concrete, it should not be greater than 20mm; 2) For shotcrete, it should not be greater than 12mm; 3) For concrete mixed with short fibers, it should not be greater than 10mm; 4) The quality of coarse aggregate should comply with the relevant provisions of JGJ 52 of the current industry standard "Sand and Stone Quality and Inspection Method Standard for Ordinary Concrete"; coarse aggregate made of stone containing activated silica shall not be used. 2 Medium and coarse sand should be used as fine aggregate, and its fineness modulus should not be less than 2.5; the quality and mud content of fine aggregate should meet the current industry standard "Sand and Stone Quality and Inspection Method Standard for Ordinary Concrete" JGJ 52 Regulation. 4.2.5 Concrete mixing water shall be drinking water or natural clean water whose water quality complies with the current industry standard "Concrete Water Standard" JGJ 63. 4.2.6 Commercial concrete can be used as concrete for masonry structure reinforcement, but the fly ash mixed in it should be Class I ash, and its loss on ignition should not exceed 5%. 4.2.7 When polymer concrete, micro-expansion concrete, steel fiber concrete, synthetic fiber concrete or shotcrete are used as structural reinforcement materials, trial preparation shall be carried out before construction, and it can be used only after its performance meets the design requirements. 4.3 Steel and welding consumables 4.3.1 The type, performance and quality of steel bars used for strengthening masonry structures shall meet the following requirements. 1 HRB335 grade and HRBF335 grade hot-rolled or cold-rolled ribbed steel bar should be used; HPB300 grade hot-rolled smooth round steel bar can also be used. 2 The quality of steel bars shall comply with the current national standards "Steel for Reinforced Concrete Part 1.Hot-rolled Plain Steel Bar" GB 1499.1, "Steel for Reinforced Concrete Part 2.Hot-rolled Ribbed Steel Bar" GB 1499.2 and "Reinforced Concrete Relevant provisions of GB 13014 on Waste Heat Treatment Reinforcement for Concrete. 3.The performance design value of reinforcement shall be adopted in accordance with the relevant provisions of the current national standard "Code for Design of Concrete Structures" GB 50010. 4 It is not allowed to use steel bars and recycled steel bars that have no factory certificate, no mark or no entry inspection. Note. If conditions permit, hot-rolled ribbed steel bars should be preferred for reinforcement of masonry structures in seismic fortification areas. 4.3.2 The quality of the reinforcement mesh used for masonry structure reinforcement shall comply with the relevant provisions of the current national standard "Steel for Reinforced Concrete Part 3.Welded Reinforcement Mesh" GB 1499.3; its performance design value shall comply with the current industry standard " Relevant provisions of JGJ 114 are adopted in Technical Regulations for Concrete Structures with Reinforced Welded Mesh. 4.3.3 The type, quality and performance of the steel plate, section steel, flat steel and steel pipe used for masonry structure reinforcement shall meet the following requirements. 1 Q235 (No. 3 steel) or Q345 (16Mn steel) steel should be used; for welded components of important structures, if Q235 grade steel is used, Q235-B grade steel should be used. 2 The quality of the steel should meet the relevant provisions of the current national standards "Carbon Structural Steel" GB/T 700 and "Low Alloy High Strength Structural Steel" GB/T 1591 respectively. 3 The performance design value of steel shall be adopted in accordance with the relevant provisions of the current national standard "Code for Design of Steel Structures" GB 50017. 4 Do not use steel without factory certificate, without mark or without entry inspection. 4.3.4 When post-anchored planting bars are used for anchors and tie parts of masonry structures, hot-rolled ribbed bars should be used instead of plain round bars. The quality of steel bars used for planting bars shall meet the requirements of Article 4.3.1 of this code. 4.3.5 When the anchor is a steel screw, a screw with full threads shall be used, and a screw without threads in the anchoring part shall not be used. The steel grade of the screw should be Q235; its quality should meet the relevant provisions of the current national standard "Carbon Structural Steel" GB/T 700. 4.3.6 The anchor bolts used in masonry structures shall be carbon steel anchor bolts specially used for masonry. The steel tensile performance index of carbon steel masonry anchor bolts shall meet the requirements in Table 4.3.6. 4.3.7 The type and quality of welding consumables used for strengthening masonry structures shall meet the following requirements. 1 The type of electrode should be compatible with the strength of the steel to be welded. 2 The quality of welding rods should comply with the relevant provisions of the current national standards "Carbon Steel Welding Rods" GB/T 5117 and "Low Alloy Steel Welding Rods" GB/T 5118. 3 The welding process shall comply with the relevant provisions of the current industry standard "Reinforcement Welding and Acceptance Regulations" JGJ 18 or "Building Steel Structure Welding Technical Regulations" JGJ 81. 4 The design principles and calculation indicators of welded joints shall comply with the relevant provisions of the current national standard "Code for Design of Steel Structures" GB 50017. 4.4 Steel wire rope 4.4.1 When steel wire mesh-polymer mortar surface layer is used to strengthen masonry structures and components, the selection of steel wire ropes shall meet the following requirements. 1 When important structures or structures are in corrosive medium environment, high temperature environment and open air environment, the mesh made of stainless steel wire rope should be selected. 2 For general structures in a normal temperature and humidity environment, meshes made of low-carbon steel galvanized steel wire ropes can be used, but effective antirust measures should be taken. 4.4.2 The steel wire used for rope making shall meet the following requirements. 1 When stainless steel wire is used, high-qua......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB 50702-2011_English be delivered?Answer: Upon your order, we will start to translate GB 50702-2011_English as soon as possible, and keep you informed of the progress. The lead time is typically in 9 seconds (download/delivered in 9 seconds). The lengthier the document the longer the lead time.Question 2: Can I share the purchased PDF of GB 50702-2011_English with my colleagues?Answer: Yes. The purchased PDF of GB 50702-2011_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. Our tax invoice, downloaded/delivered in 9 seconds, includes all tax/VAT and complies with 100+ countries' tax regulations (tax exempted in 100+ countries) -- See Avoidance of Double Taxation Agreements (DTAs): List of DTAs signed between Singapore and 100+ countriesQuestion 4: Do you accept my currency other than USD?Answer: Yes. If you need your currency to be printed on the invoice, please write an email to Sales@ChineseStandard.net. In 2 working-hours, we will create a special link for you to pay in any currencies. Otherwise, follow the normal steps: Add to Cart -- Checkout -- Select your currency to pay. |