Principles and methods of structural optimization of frame-shear wall?

(1) Dispersion: In the layout of shear walls, seismic forces acting on multiple shear walls with approximately equal stiffness should be considered. Because if the earthquake force is concentrated on one or two shear walls with high stiffness, it will cause great cultural internal force and difficult cross-section design, and once the main shear wall is destroyed, other weak shear walls and frames can hardly bear the large earthquake force from the shear wall, causing damage:

(2) Uniformity: the shear force in the same direction should be evenly distributed on all sections of the building plane, rather than concentrated on a certain section, so as to prevent the uneven distribution of seismic force between frames due to large horizontal deformation of the building;

(3) Perimeter: Shear walls should be arranged along the periphery of the structural plane as far as possible to obtain the maximum horizontal arm of structural resistance and fully improve the torsional capacity of the whole structure;

(4) Symmetry: Shear walls should be arranged symmetrically as far as possible. If it is difficult to arrange symmetrically on the plane, we can adjust the length and thickness of the shear wall to make the center of thrust stiffness of the structure as close as possible to the center of mass, so as to reduce the eccentricity and reduce the torsional vibration of the structure during the earthquake.

(5) In an independent structural unit, the shear wall in the same direction should not be a single-limb wall, and more double-limb walls or multi-limb walls should be set. A single shear wall member should be designed as a frame shear wall with beams and columns (or hidden beams and columns) around it, and the vertical and horizontal shear forces are connected together to form L-shaped, T-shaped, [shaped, cross-shaped and so on. To prevent all shear walls in the same direction from yielding at the bottom at the same time, forming an unstable lateral displacement mechanism;

(6) In general, the shear wall is arranged in the place where the vertical load is large, where the plane shape changes or the horizontal stiffness of the floor changes greatly, and where the stairwell, elevator and pipeline merge. Longitudinal shear walls should not be set at both ends of independent structural units, so as to avoid large shrinkage and temperature stress of longitudinal frame beams and floors due to too long deformation constraint sections;

(7) Windows and doors of shear walls should be aligned up and down to form clear limbs and coupling beams, and staggered walls should not be adopted. The layout of shear wall has a great influence on the lateral stiffness of the structure. Discontinuity of shear wall edge height will cause sudden change of structural stiffness, so try not to set corner windows. When it is unavoidable, strengthening measures such as increasing wall thickness, plate thickness and setting hidden beams should be taken at the corner to ensure that the stiffness of adjacent floors is weakened by no more than 30%;

(8) The shear wall should be set at the position where there is no need to open a big hole in the wall (to ensure sufficient rigidity): the length-width ratio of the building with no big hole between the shear walls and the roof should not be greater than 3. If it exceeds, the influence of in-plane deformation of the floor should be considered;

(9) Shear walls are characterized by large in-plane stiffness and bearing capacity, but relatively small out-of-plane stiffness and bearing capacity. Therefore, the bending distance out of the plane of shear wall should be avoided as far as possible. The floor beam should not be placed vertically on the I-shaped shear wall unilaterally. When the wall limb of shear wall is connected with the floor beam in the out-of-plane direction, measures should be taken according to the requirements of the specification.

(10) Some short-leg shear walls should be arranged on the structural plane to form a shear wall system with the same horizontal resistance as general shear walls;

Axial compression ratio (1 1) is also an important reference index for shear wall design. If it is too small, it shows that the mechanical properties of the material have not been fully utilized, and some shear walls should be reduced.

(12) The structure with lower stiffness bears less floor shear and bending moment.

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