GB/T 51408-2021 English PDF
Basic dataStandard ID: GB/T 51408-2021 (GB/T51408-2021)Description (Translated English): (Building isolation design standard) Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: P15 Word Count Estimation: 150,118 Issuing agency(ies): Ministry of Housing and Urban-Rural Development of the People's Republic of China; State Administration for Market Regulation GB/T 51408-2021: (Building isolation design standard)---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 In order to implement the national laws and regulations on earthquake prevention and disaster reduction in construction projects, implement the policy of focusing on prevention, so that after the building adopts seismic isolation technology, the earthquake safety is further improved, and the function of the building after the fortification earthquake is not short, To avoid casualties and secondary disasters, reduce social impact and economic losses, this standard is formulated. 1.0.2 This standard applies to the seismic isolation design of buildings in areas with a seismic fortification intensity of 6 degrees and above and the seismic isolation and reinforcement design of existing buildings. 1.0.3 Except for special regulations, the basic fortification objectives of earthquake-isolated buildings are. when subjected to a fortified earthquake equivalent to the basic intensity of the region, the main structure can continue to be used without damage or repair; When the structure may be damaged, it can continue to be used after being repaired; when the special fortification building is subjected to an extremely rare earthquake, it will not collapse or cause life-threatening serious damage. 1.0.4 When there are special requirements for the use functions of the structural components, non-structural components and auxiliary equipment of the earthquake-isolated building, in addition to meeting the basic fortification objectives, they shall also meet the provisions of the seismic performance standards for structural components, non-structural components and auxiliary equipment. 1.0.5 When the height, regularity, structure type, and setting of seismic isolation floors of seismic-isolated buildings exceed the relevant standards or there are special requirements such as seismic fortification standards, it is advisable to use the structural seismic performance design method for supplementary analysis in accordance with Appendix A of this standard and argument. 1.0.6 The design of seismically isolated buildings and the seismically isolated and reinforced design of existing buildings shall not only comply with this standard, but also comply with the provisions of the current relevant national standards. 2 Terminology and symbols2.1 Terminology 2.1.1 Seismically isolated building In order to reduce the seismic response, a building with a seismic isolation layer is set in the structure to realize the seismic isolation function, including the upper structure, the seismic isolation layer, the lower structure and the foundation. 2.1.2 Seismic isolation A general term for all components of an earthquake-isolated building set between the foundation, the bottom or the substructure and the superstructure, including earthquake-isolation bearings, damping devices, wind-resistant devices, limit devices, tensile devices, auxiliary devices and related supporting or connection components, etc. 2.1.3 superstructure superstructure Seismic isolation buildings are located in the structural part above the seismic isolation layer. 2.1.4 Substructure Seismic isolation building is the structural part located below the seismic isolation layer, excluding the foundation. 2.1.5 Base isolation base isolation The seismic isolation system is set at the bottom of the building. 2.1.6 inter-storey isolation The seismic isolation system is set at a position above the bottom of the building. 2.1.7 roof isolation The seismic isolation layer is set between the building column top or wall top and the top roof of the seismic isolation system. 2.1.8 Seismic isolator The seismic isolation layer is used to carry the upper structure and has a bearing with seismic isolation and deformation capacity. 2.1.9 damping device damping device A device that attenuates the seismic response of an isolation layer by absorbing and dissipating seismic input energy. 2.1.10 anti-wind device anti-wind device The seismic isolation layer is a device used to resist the wind load of the superstructure, which can be an integral part of the seismic isolation bearing or can be set separately. 2.1.11 Anti-tension device The device used in the seismic isolation layer to resist the vertical tension caused by the overturning action of the superstructure. 2.1.12 limit device stopper A device that limits the displacement of an isolation layer beyond a reasonable design range. 2.1.13 Base shear ratio The ratio of the shear force at the bottom of the upper structure of the building structure after seismic isolation to that before isolation. 2.1.14 Equivalent stiffness equivalent stiffness The secant stiffness of an isolator or isolator for a specific horizontal displacement. 2.1.15 Equivalent damping ratio equivalent damping ratio The damping ratio of an isolating layer or isolating mount for a particular pair of horizontal displacements. 2.1.16 very rare earthquake Earthquake motion with annual exceedance probability of during the design reference period. 2.2 Symbols 2.2.1 Action and action effect. 2.2.2 Material properties. 2.2.3 Geometric parameters. 2.2.4 Calculation coefficient. 2.2.5 Others.3 basic rules3.1 General provisions 3.1.1 The seismic fortification category of seismically isolated buildings shall be determined in accordance with the relevant provisions of the current national standard "Classification Standards for Seismic Fortification of Construction Engineering" GB 50223. 3.1.2 For seismically isolated buildings, a reasonable seismic isolation scheme should be determined according to the building's seismic fortification category, design ground motion parameters, site conditions, building structure type, and use requirements. 3.1.3 Under fortified earthquakes, the bearing capacity and deformation of the structure and the isolation layer should be checked; under rare earthquakes, the deformation of the structure and the isolation layer should be checked, and the bearing capacity of the isolation layer should be checked. Check calculation; under the action of extremely rare earthquakes, the deformation check calculation of the structure and the isolation layer should be carried out for special fortification buildings. 3.1.4 The design service life of the seismic isolation bearing in the seismic isolation layer should not be lower than the design service life of the building structure. When the design service life of other devices in the seismic isolation layer is lower than the design service life of the building structure, replaceable measures shall be indicated and preset in the design. 3.2 Site, foundations and foundations 3.2.1 The site of the earthquake-isolated building should choose the favorable location for earthquake resistance, and avoid the unfavorable location; when it cannot be avoided, effective measures should be taken. 3.2.2 The foundation of the earthquake-isolated building should be stable and reliable, and the site where it is located should be Category I, II, and III; when the site is Category IV, effective measures should be taken. 3.2.3 The design and seismic calculation of the foundation of the earthquake-isolated building shall meet the requirements of seismic fortification intensity in the region. 3.2.4 The anti-seismic structural measures of the foundation foundation of earthquake-isolated buildings shall comply with the provisions of the current national standard "Code for Seismic Design of Buildings" GB 50011.For the anti-liquefaction measures of the foundation of key fortified buildings, it shall be determined by increasing the liquefaction level; for special The foundation anti-liquefaction measures of fortified buildings should be specially studied, and should not be lower than the corresponding requirements of key fortified buildings until liquefaction subsidence is completely eliminated. 3.3 Experiments and observations 3.3.1 For special fortification-type seismic-isolation buildings, complex-shaped or special-required seismic-isolation buildings, the seismic shaking table test of the structural model can be used for supplementary verification of the seismic-isolation scheme. 3.3.2 Seismic response observation system shall be set up for important or special seismically isolated buildings. 3.3.3 Seismic isolation buildings should be equipped with devices for recording the seismic deformation response of the isolation layer.4 Earthquake action and structure isolation check calculation4.1 General provisions 4.1.1 The seismic action of a seismically isolated building shall meet the following requirements. 1 In general, the horizontal seismic action shall be calculated separately at least in the two principal axis directions of the building structure, and the horizontal seismic action in each direction shall be borne by the lateral force-resistant members in this direction; 2 For structures with oblique lateral force-resisting members, when the intersection angle is greater than 15°, the horizontal earthquake action in the direction of each lateral force-resisting member shall be calculated separately; 3 The method of adjusting the effect of earthquake action can be used to take into account the torsional effect of the isolated structure; for structures with obviously asymmetric mass and stiffness distribution, the torsional effect under two-way horizontal earthquake action should be included; 4 For long cantilever or long-span structures with seismic fortification intensity of 7 (0.15g), 8 and 9, and high-rise building structures with 9 degrees, the vertical seismic action shall be calculated. 4.1.2 The analysis model of the isolated structure shall meet the following requirements. 1 The selected analysis model should be able to reasonably reflect the actual force status of the components in the structure; 2 The superstructure and substructure can choose calculation models such as multi-mass system, space bar system, space bar-wall plate element or shell element, continuum and other combined finite elements; 3 The calculation model for the seismic isolation support and damper of the seismic isolation layer that can correctly reflect its characteristics shall be selected. 4.1.3 For the calculation of seismic action of isolated structures, the following methods may be adopted except for special requirements. 1 The bottom shear force method may be adopted for the seismically isolated buildings whose building height is not more than 24m, the upper structure is mainly shear deformation, and the mass and stiffness are relatively evenly distributed along the height; 2 The vibration-isolated structures other than item 1 of this article shall adopt the mode decomposition response spectrum method; 3 For seismic-isolated buildings with building height greater than 60m, irregular buildings, or complex-combined seismic-isolated buildings with seismic isolation bearings, damping devices and other devices, time-history analysis method should be used for supplementary calculation. The shear force at the bottom of the structure calculated by each seismic acceleration time history curve should not be less than 65% of the result calculated by the modal decomposition response spectrum method, and the average value of the shear force at the bottom of the structure calculated by multiple time history curves should not be less than the modal decomposition response spectrum 80% of the calculated results. 4.1.4 When within 10㎞ of the seismogenic fault, the calculation of the seismic action of the isolation structure should take into account the near-field effect and multiply it by the amplification factor. It should be 1.25 within 5㎞ and not less than 1.15 outside of 5㎞. 4.2 Design response spectrum and ground motion input 2 The seismic design conditions shall be checked and calculated according to the provisions of Article 4.4.4 and Article 4.4.6 of this standard. 4.2.2 Under permanent design conditions and short-term design conditions, when the linear relationship between load and load effect is considered, the effect design value of the basic combination of loads should be determined according to the following formula. Note. For bookstores, archives, storage rooms, ventilator rooms and elevator machine rooms, where the combined value coefficient of the floor live load in this article is 0.7, it should be 0.9. 4.4.3 In the permanent state design and transient design state, the sub-item coefficients of the basic combination of loads shall be adopted according to Table 4.4.3. 4.4.4 Under earthquake design conditions, the design of seismically isolated structural components adopts the basic combination of earthquakes that does not take into account the wind load effect, and the bearing capacity design under fortification earthquakes should be carried out according to the basic fortification objectives in Article 1.0.1 of this standard. 4.4.5 Seismic isolation structural components can be divided into key components, common vertical components, important horizontal components and common horizontal components according to performance requirements. For steel members under pressure, in addition to checking the strength according to Article 4.4.6 of this standard, their stability should also be checked. 4.4.6 Under the action of fortification earthquake, the structural components of the earthquake-isolated building shall be designed according to the following provisions. 1 The seismic bearing capacity of key components shall meet the elastic design requirements, and shall comply with the following formula. 2 The shear bearing capacity of ordinary vertical members and important horizontal members shall comply with the provisions of formula (4.4.6-1), and the bearing capacity of normal sections shall comply with formula (4.4.6-2) and formula (4.4.6-3) Provisions. 3 The shear bearing capacity of ordinary horizontal members shall comply with the provisions of formula (4.4.6-2), and the bearing capacity of the normal section of members shall comply with the provisions of formula (4.4.6-4). 4.4.7 When calculating the seismic action of the fortification, the shear force corresponding to the standard value of the seismic action of each floor of the isolation structure shall meet the requirements of formula (4.4.7). 4.5 Check calculation of superstructure deformation 4.5.1 Under the fortification earthquake action of the upper structure, the maximum elastic inter-story displacement in the structural floors shall comply with the following formula. 4.5.2 Under the rare earthquake action of the superstructure, the maximum elasto-plastic story displacement in the story shall comply with the following formula. 4.5.3 The maximum elasto-plastic inter-story displacement in the structural storey of the superstructure of the special fortification-type seismic-isolation building shall still be checked and calculated according to the formula (4.5.2) of this standard under extremely rare earthquakes, and the elasto-plastic inter-story displacement angle Limits should comply with the provisions of Table 4.5.3. 4.6 Design of seismic isolation layer 4.6.1 The design of the seismic isolation layer shall meet the following requirements. 1 The damping device, wind resistance device and tensile device can be integrated with the shock-isolation support, or can be set separately, and a limit device can be set when necessary. 2 When multiple types and specifications of seismic isolation devices are selected for the same seismic isolation layer, the bearing capacity and horizontal deformation capacity of each seismic isolation device should be fully utilized, and the vertical deformation of all seismic isolation devices should be kept basically the same. Rubber bearings should not be mixed with steel bearings such as friction pendulums in the same isolation layer. 3 When the isolation layer adopts the friction pendulum isolation support, the vertical displacement generated when the support slides horizontally and its influence on the isolation layer and structure should be considered. 4.6.6 The horizontal displacement of the isolation bearing under the action of the earthquake shall comply with the following formula. The horizontal displacement of the isolation bearing under the action of the earthquake is taken according to the following regulations. 1 Unless otherwise specified, the value of the isolation rubber bearing under rare earthquakes should not be greater than the smaller value of 0.55 times the diameter of the bearing and 3.0 times the sum of the rubber thicknesses of each layer; The value should not be greater than 0.75 times the horizontal limit displacement of the product; the value of the friction pendulum isolation bearing should not be greater than 0.85 times the horizontal limit displacement of the product. 2 For special fortification buildings, the value of the isolation rubber bearing can be taken as 4.0 times the sum of the rubber thicknesses of each layer under the action of extremely rare earthquakes; Displacement; the isolation layer should be equipped with a limit device that exceeds the displacement under extremely rare earthquakes. 4.6.7 The horizontal limit deformation or horizontal limit displacement of seismic isolation bearing products shall be subject to the product type inspection report; the horizontal limit deformation of vibration isolation rubber bearing products shall not be less than 4.0 times the sum of the rubber thicknesses of each layer; The horizontal limit displacement of the skateboard bearing product should not be less than the maximum value of the horizontal limit displacement of the vibration-isolation rubber bearing product in the same isolation layer. 4.6.8 The wind resistance bearing capacity of the seismic isolation layer shall comply with the following formula. 4.6.9 The anti-overturning calculation of earthquake-isolated buildings shall meet the following requirements. 1 The anti-overturning calculation of the whole structure and the tension and compression bearing capacity of the isolation support shall be checked for the seismically isolated building. 2 When checking the anti-overturning calculation of the overall structure, the overturning force should be calculated according to the rare earthquake action... ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 51408-2021_English be delivered?Answer: Upon your order, we will start to translate GB/T 51408-2021_English as soon as possible, and keep you informed of the progress. 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