shear wall

How to arrange shear wall formwork

Wall limbs should be aligned to avoid misalignment

Shear wall members are the main anti-sliding members of high-rise shear wall structures. During structural design, the linkage effect between the wall limbs should be fully utilized to minimize the independent horizontal resistance of the wall limbs. Therefore, when performing structural layout, the wall limbs in the same direction should be evenly arranged to form a multi-joint shear wall on the plane to work together.

The shear wall should be evenly arranged, and the wall limbs at the edge should be properly strengthened

As a vertical load-bearing member of high-rise buildings, the shear wall is evenly arranged to reduce the axial pressure difference between the wall limbs and avoid uneven settlement of the foundation due to uneven stress. In addition, the building structure should have a certain torsional stiffness in addition to meeting the needs of bearing vertical loads and lateral stiffness of the structure. Practical experience shows that strengthening the anti-lateral displacement members at the edges of the structure in two directions is the most effective way to enhance the torsional rigidity of the structure and reduce the torsional effect of the structure. In the specific design process, the structural engineer can adjust the relative position of the structural stiffness center and the structural plane geometric center and mass center by appropriately strengthening the surrounding shear walls and outer ring beams, and try to achieve the ideal effect of “three centers” coincide.

Reasonably determine the length of the wall limbs, reduce the short limb walls and the super long walls

Short-leg shear wall refers to a shear wall with a cross-sectional width of not more than 300mm and a cross-sectional aspect ratio of 4-8. Due to the poor ductility of short-limb shear walls, the high structural requirements, the large amount of steel reinforcement, and the poor economy, the use of short-limb shear walls should be avoided as far as possible in structural layout.

Ultra-long wall refers to a shear wall with a wall limb length greater than 8m or a single wall limb subjected to horizontal seismic shear in this direction greater than 30% of the total floor shear. If the length of the wall limb is too long and the stiffness is too large, the seismic force on the wall limb will be relatively concentrated. If there is an ultra-long wall in the structure, this part of the wall limb will be destroyed firstly due to the huge seismic force when an ultra-strong earthquake occurs, and the bearing capacity of the other wall limbs is relatively weak, which is likely to cause the shear wall to be damaged by various damages. , Eventually causing the entire structure to collapse. Therefore, when arranging the structure of the shear wall, the stiffness of each wall limb should be as close as possible to avoid the appearance of super long walls.

Prioritize the layout of L-shaped and T-shaped walls, and less use of flat walls

L-shaped and T-shaped shear walls have good stability due to the wing wall at the end of the wall limbs. At the same time, the frame beams outside the shear wall are lapped on the wing wall. It has a good anchoring effect on the frame beam, so it should be preferred in structural design. However, from the perspective of material design, the length of L-shaped and T-shaped wing walls should not be too long, as long as they meet the basic requirements of relevant codes. Because of the poor out-of-plane stability of the flat wall, and for the residential high-rise shear wall structure, the wall thickness is often limited. If the axial compression of the bottom leg of the structure is relatively large or the frame beam is lapped on one side, the wall The limbs are prone to instability and damage under the action of earthquakes, so it is better to use the shear wall as little as possible during the design process.

Empirical data of average weight of shear wall structure

The most common high-rise shear wall residential project in engineering design (using light partition materials), the average weight law is generally as follows.

(1) 6-degree fortification area: 20 floors for 13.0KN / ㎡; 30 floors for 14.0KN / ㎡; 40 floors for 15.0kN / ㎡.

(2) 7-degree fortification area: 20 floors for 14.0KN / ㎡; 30 floors for 15.0KN / ㎡; 40 floors for 16.0kN / ㎡.

(3) 8-degree fortification area: 20 floors for 15.0KN / ㎡; 30 floors for 16.0KN / ㎡; 40 floors for 17.0kN / ㎡.

The unit type is small, and the average weight will be larger when there are more partition walls; the unit type is larger, and the average weight will be smaller when there are fewer partition walls.

If the average weight of the SATWE calculation results differs from the above rule by more than 10%, you should go to PMCAD “② Plane Load Display Check” to check carefully whether the load input is correct. When the average weight in the calculation result is too large, it is generally possible that the load input is too large or the line load is repeatedly input; when the average weight in the calculation result is small, it is generally possible that the load input is missing.

Frame-The suitable range of the overturning moment of the shear wall

To make the frame-shear wall into an organic combination structure system with two lines of defense, the layout and design of the shear wall and frame should be rationally arranged so that the stiffness characteristic value is within a reasonable range of 1 ~ 2.5. According to relevant research and design practice, when the stiffness characteristic value is within a reasonable range of 1 to 2.5, the height of the floor with the maximum floor displacement angle under earthquake is about 0.6H, and the overturning bending moment for a 20-story building frame part is 40 About 30%, the overturning bending moment for a 30-story building frame part is about 30%, for a 40-story building frame part is about 20%, the frame-shear wall design is the most reasonable, Collaborative work is the most effective and the structural cost is the most economical.