Description of the problem: “Technical Regulations for Concrete Structures of High-Rise Buildings” ( JGJ 3-2002 ) Article 3 of 7.1.2 mentions that “in seismic design, the seismic rating of short-limb shear walls shall be lower than the shears specified in Table 4.8.0 of this Regulation “Improved the seismic level of the force wall by one level”, but I went through the “Technical Specifications for Concrete Structures of High-Rise Buildings” ( JGJ 3-2010 ) that did not mention that the short-limb shear wall needs to increase the seismic level? Did the new regulations cancel this provision? Colleagues also said that the calculation data of the short-limb shear wall submitted for review did not increase the earthquake resistance level, and the response to the review did not require changes.
Answer: Article 7.2.2 “The seismic rating of the short-limb shear wall is no longer improved, but the limit value of the axial compression ratio is reduced in paragraph 2 ” This is different from the old version of the high regulation.
Is the design of the shear wall connecting beams and beams with beams and plates together?
Answer: Definition of connecting beam
Coupling beam: refers to the beam connecting the wall limb and the wall limb, the wall limb and the frame column in the shear wall structure and the frame shear structure. The connecting beam has the characteristics of generally small span (usually less than 5 ), a large cross-section, and a large rigidity of the wall connected to the connecting beam. Generally, under the action of wind load and earthquake load, the internal force of the coupling beam is often very large.
The distinction between connecting beams, secondary beams and frame beams: usually frame beams are the beams between the columns in the frame structure; secondary beams are the beams that are placed on the frame beams at both ends; connecting beams are the walls in the shear wall structure The beam between the wall and the frame beam is a member mainly bent and deformed; the connecting beam is a member mainly sheared and deformed. The frame beam is a member supported by the column to support the beam. The upper load is directly supported by the beam, and then the beam transmits the load to the column. The connecting beam transfers the load from the connecting beam to the wall. In terms of appearance, the span ratio of general frame beams is greater than 5 ; and the span ratio of connecting beams is less than 5 .
Does the shear wall reinforcement require seismic resistance? Can you talk about it with the relevant specifications?
Answer: There is a difference in the seismic grade of the shear wall structure. However, in the seismic design specifications of buildings from GB50011-2001 to the updated GB50011-2010 , there has never been a provision that the reinforcement of the shear wall must meet the reinforcement index of the E- shape About “yield ratio”, “yield ratio”, “elongation at maximum tension”). If it is inconvenient for the landlord to check GB50011-2010 , first pass a picture of Article 5.2.2 (Strong Article) of Construction Quality Acceptance Specification for Concrete Structure Engineering and carefully consider it.
In order to ensure that the shear wall structure has good seismic performance, what are the relevant conceptual designs?
Answer: In the ” Code for Seismic Design of Buildings” ( GB50011-2010 ), Chapter 3 basically stipulates 3.9 Structural materials 3.10 Seismic performance-based design of buildings, Chapter 4 site and foundation, Chapter 6 Basic seismic structure measures for seismic walls Chapter .. …. etc., the design concept of anti-seismic is everywhere, basically throughout the text of this code, this answer box can not accommodate all the content.
Earthquake destructive force is a natural force second only to the cosmic force. Humans cannot compete with it. What we can do is to prevent it, consume it, avoid it, delay it, reduce its damage, etc. It is derived from the lessons learned from the earthquake damage investigation, and a comprehensive concept is derived, which is used to guide our seismic design and construction.
05. Question 5
Whether the frame-supported shear wall structure of non-seismic design should be provided with constrained edge members (Case)
Problem description: A 92- meter high-rise residential building with conversion is under construction. The bottom two floors are commercial podiums, the upper 26 floors are residential, and the conversion floors are podium surfaces (that is, the conversion floor is the second floor). The project is located in a non-earthquake-resistant area. Earthquake resistance is not considered. Will the bottom reinforcement of the shear wall and the adjacent upper layer be provided with constraining edge members? Also, how should the axial compression ratio limit of such non-seismic high-rise building shear wall be taken?
Answer: Please refer to Article 7.1.6 of “Technical Specification for Concrete Structure of High-Rise Building” ( JGJ3-2010 ) ; 7 ．2 . 1-4 When the non-seismic design, bw should not be less than 160mm ; 7 ．2 . Article 14 … should be in accordance with Article 7 . 2 . 16 sets of structural edge members; 7 ．2 . 16-5 For shear walls of non-seismic design, the end of the wall limbs should be equipped with not less than 4 Φ 12 longitudinal steel bars, the stirrup diameter should not be less than 6mm , and the spacing should not be greater than 250mm . 7 . 2 . 25. In non-seismic design of connecting beams of shear wall structure, it should be … 7 ; 1 . 6… The longitudinal reinforcement ratio of concealed columns and buttress columns in non-seismic design is ≥ 0.5% ; the specification does not require the axial compression ratio, nor does it require the setting of constraining edge members. In short , there are also non-seismic design requirements in Sections 7.1 and 7.2 . Since your house is 92m high and close to super high, it is not known as A -level or B -level height. It is recommended that you compare the structure with the fourth-level seismic structure.
06 , question six
Reinforcement requirements for second-level earthquake resistance of shear walls?
Problem description: The seismic rating in the drawing description is Grade II of the shear wall. In the material description: the ratio of the measured value of the tensile strength to the measured value of the yield strength of the longitudinal reinforcement in the end columns of the shear wall and the staircase shall not be less than 1.25 ; and The ratio of the measured value of the yield strength of the steel bar to the standard value of the strength should not be greater than 1.3 ; the measured value of the total elongation under the maximum tension should not be less than 9% . However, the concrete structure acceptance code mentions that for structures with seismic fortification requirements, the performance of the longitudinally stressed steel bars should meet the design requirements; HRB335E , HRB400E , HRB500E , HRBF335E , HRBF400E or HRBF500E steel bars should be used for the longitudinally stressed steel bars in the bracing members (including ladder sections). The measured values of the strength and the total elongation at the maximum force should meet the following requirements: Three Articles.
07 、Question 7
Where should I use seismic reinforcement in the drawings? Can you communicate with the design institute, except for the raft and the retaining wall, all the other parts are earthquake-resistant steel bars (that is, with E ) because they have entered the site. Or are there any other specific requirements?
Answer: The requirements stated by the landlord on the mechanical index requirements for seismic reinforcement are found in Article 5.2.2 (Strong Article) of the Code for Construction Quality Acceptance of Concrete Structure Engineering ( GB50204-2011 ) ( 2011 Edition ). The article clearly stipulates that the scope of application is: the longitudinally stressed steel bars in frames and diagonal bracing members (including ladder sections) designed for the first, second, and third seismic grades, and does not include the reinforcement of the shear wall (except for the connection beam). Cross braces). There are no seismic structural measures for rafts and retaining walls, secondary beams, slabs, foundations and other components. This is the content of the seismic design code. These could not have been necessary to communicate with the design institute, but the theme of the building stated that the “drawings in the material description” said that “seismic reinforcement”, whether the engineering nature is too important, is classified as a special fortification category, or the designer did not The norm is thoroughly eaten?
If you are the construction unit, because the budget has been made according to the drawings, it is safe to purchase the seismic reinforcement completely, eliminating the trouble of on-site material management, and there will be no mistakes of mixed use. The appearance of anti-seismic and non-anti-seismic steel bars is the same, so workers can easily ignore them and mix them.
08 , question eight
Atlas 11G101 – 1 of 74 pages, 75 pages, stirrups opening shear wall beams are down, the feeling is Atlas wrong again.
Answer: Refer to (Building Construction Manual, Fifth Edition, Volume 3 , Page 33 ) the requirements for the position of the closed stirrup hook, and think that the atlas error is consistent!
① The first screenshot is indeed not a regulation, regulation or standard. It is the requirement for the position of the closed stirrup hook in Volume 3 of the Fifth Edition of the Construction Manual . His requirement: When there is no cast-in-place slab at the top or bottom of the beam (understand that the upper part is the ordinary beam L of the wall or precast slab ), the position of the hook is set at the top of the beam. Understand that LL , AL , BKL are not included.