Reinforced concrete shear walls are the main lateral force-resisting members of high-rise buildings. The nonlinear analysis of the shear wall by the finite element method requires a large amount of calculation. To this end, people have established a variety of shear wall macrocell models, in order to obtain a solution with a certain precision with a small amount of calculation. In the shear wall macrocell model composed of springs, the stiffness of the vertical spring is determined by the uniaxial constitutive relationship of the concrete, which is relatively simple; the processing of the horizontal shear spring stiffness is more complicated. Since Vecchio and Collins proposed the modified nip theory (MCFT), the shear spring stiffness is mostly calculated by coordinate transformation and MCFT. To do this, you need to give the boundary conditions of the macrocell. The most common requirement is that the stress in the horizontal direction is Rx = 0. However, since the corresponding Ex is unknown, the constitutive relationship needs to be iteratively implemented. In this paper, Ex=0 is used as the element boundary condition, so that the iterative calculation can be avoided when using the constitutive relation. However, the qualitative analysis can be that the area near the edge of the shear wall is more close to the free boundary and Rx=0. The strong horizontal constraint is more consistent with Ex=0; Ex=0 is consistent with the rigid horizontal rod in the macrocell. Determining the elastic strain requires iteration. This paper proposes to use MCFT under a full strain spindle so that no iteration is required. This paper will demonstrate that the two are equivalent when solving the total stiffness equation by iterative method. In this paper, a new type of six-degree-of-freedom rigid-rod spring unit is proposed, and the shear wall macrocell model considering the horizontal section shear warpage of the wall is used, and the above several cases are calculated to find the overall analysis accuracy. Under the premise of the smallest amount of calculations.
It can be seen from the above that the two vertical springs are arranged at the Gauss point, and the static force will be more accurately satisfied in the case of the same amount of calculation compared with the other positions (such as between the upper and lower nodes). Equivalence (this can be precise if the stress distribution can be approximated by a polynomial not exceeding twice in the horizontal span of the element); and it can satisfy the static with the same accuracy compared to multiples distributed along the x direction. Reduce the amount of calculation under the premise of equivalent. The example is to compare the difference between the different shear spring superposition method and the concrete two-axis constitutive relation, and perform an elastoplastic pushover (pushOover) analysis on a medium-high shear wall under the horizontal load. The additional virtual spring method is used for the stiffness problem). The strength grade of shear wall concrete is C25. The dimensions, section reinforcement and unit division are shown. The axial compression ratio is 013. The horizontal value of the test piece / load F) The lateral value of the $0 hysteresis return envelope and the experimental value See the theoretical curve of the overlying analysis; see the relationship between the average shear stress of the two Gauss points in the elements A to F and the shear strain (equal shear strain). Among them, the modes 1P1 and 1P2 indicate that the shear spring adopts Ex=0, and the two-axis constitutive relationship adopts two modes based on the full strain main shaft system and the elastic strain main shaft system respectively; the modes 2P1 and 2P2 indicate that Rx=0 is used. The two-axis constitutive relationship is based on the full-strain main shaft system and the elastic strain main shaft system.
Conclusion (1) The iterative method is used to analyze the shear wall. The shear strain relationship between the MCFT based on the full strain main axis and the MCFT based on the elastic strain main axis is equivalent. (2) The shear capacity of the elements obtained by using different element boundary conditions (Ex=0 and Rx=0) is basically equal; the shear stiffness of the elements before yielding is also basically equal, but there is a big difference after yielding. (3) Different treatment methods have little effect on the bearing capacity and stiffness of the medium-high shear wall. Therefore, from the point of view of reducing the amount of calculation without affecting the overall analysis results, it is recommended to use Ex=0 and the full-strain based spindle system. 1(4) adopts bidirectional assembly by basic macrocells (rather than other only along the axis). The shear wall macrocell model is assembled to the shear wall to reflect the shear warp of the section, and the distribution of the shear stress in the section can be obtained.
What is paint stained Steel Grating?
Painted and painted steel gratings are mainly for the surface treatment of steel gratings. The general surface treatment of steel gratings is hot-dip galvanized steel gratings. The same surface painting is also an important one. Painted steel gratings have a lower processing cost than hot-dip galvanized steels. They have moderate rust resistance and are relatively resistant to wear. However, paints can be selected in a variety of colors, especially when steel gratings are used in mechanical equipment. The color is required to be consistent, so that we use spray paint for surface treatment.
Sprayed steel grating specifications:
- Height (or width) and thickness of painted flat steel panels; flat steel height is usually 25mm, 30mm, 32mm, 35mm, 40mm, 45mm, 50mm, etc. Flat steel plate thickness 3mm, 4mm, 5mm, etc.;
- Surface treatment of Painted Steel Grating: spray paint, dyeing paint;
- spray steel grating is loaded by the flat steel spacing: the center distance between two adjacent loads flat steel, commonly used 30mm, 40mm, and sometimes 60mm.
- Spacing of the steel grating crossbar: The distance between the centers of two adjacent crossbars is usually 50mm, 100mm, and both can be produced according to customer requirements
The advantages and disadvantages of sprayed steel gratings:
Compared with the hot-dip galvanized steel grid plate and the stainless steel grid plate, it has the remarkable feature of low cost; in addition, since the painted steel grid plate can spray the surface into black, white, red, gray and other colors, it can be the same with the surrounding environment. The color of the equipment is consistent with the style, and it looks better than other steel gratings. Its anti-corrosion layer is easy to fall off, its anti-corrosion effect is far less than the hot-dip Galvanized Steel Grating, in the corrosive environment, the service life is far less than the hot-dip galvanized steel grating and Stainless Steel Grating.
Painted Steel Grating
Spraying Lacquer Steel Grating, Brushing Lacquer Steel Grating, Soaking Lacquer Steel Grating
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