Poor tensile properties of concrete and subsequent cracking is a major cause of the nonlinearity of reinforced concrete structures. There are currently three main types of concrete crack models:
(1) Discrete crack model, which is a model commonly used in the early research stage, it assumes that the crack is separate and occurs between the boundaries of each unit. The disadvantage of this model is that the unit grid must be continuously modified and new nodes added to make The calculation work is very cumbersome;
(2) Distributed crack model, assuming that the tensile stress and shear stress of cracked concrete maintain a certain continuity, treated as an anisotropic material, the advantage of this model is that cracks can be randomly generated and can predict the direction of crack propagation, The disadvantage is that the crack width cannot be calculated;
(3) The fracture mechanics model is mainly used to study the expansion and instability of concrete that has cracks. It is currently limited to the treatment of single cracks in plain concrete. How to deal with batches of cracks is still being explored.
In recent years, some scholars have linked the development of cracks with fracture energy and quoted the concept of equivalent fracture deformation to make the above distributed crack model more complete. In the nonlinear finite element analysis of reinforced concrete, there are three main ways to simulate reinforcement:
(1) Distributed, the model assumes that the steel bars are distributed on the entire unit at a certain angle, and at the same time assumes that the concrete and the steel bars are fully bonded. The combined constitutive relationship of concrete and steel bars is used. This model is suitable for steel bars along the The situation where the structure is more evenly distributed, such as shear walls and deep beams;
(2) Buried type, this model is mostly used for high-order equal elements. Rebar is used as an axial member in the isoparametric element. It must assume that the concrete and the reinforcement are completely bonded and the reinforcement is compatible with the deformation of the element;
(3) Discrete, this model superimposes one-dimensional reinforcement elements into two-dimensional concrete, and connects different elements at the nodes. The one-dimensional reinforcement elements can be axial force rod elements hinged at both ends or nodes at both ends. For three-degree-of-freedom beam elements, the discrete model can calculate the relative displacement between steel and concrete, and it is relatively simple and the most widely used.
The bond between steel and concrete allows the internal forces of the two materials to be transferred to each other. Due to the different simulations of steel bars, the simulation of bonding between steel bars and concrete is also different. For the separated and buried steel bar models, it must be assumed that the steel bar and the concrete are completely bonded, and that the steel bar and the concrete have no relative slip, so-called ideal bonding, this assumption is different from the actual situation, especially In the cracks. In order to simulate the possible relative slippage between steel and concrete, most of the current use of discrete steel models.
Therefore, the steel lined reinforced concrete pressure pipes used in the hydropower station in the project can be arranged on the downstream face of the concrete, and can also be arranged on the ground, such as the pressure pipes of the pumped storage power station. Its design principle is to allow radial cracks in the concrete under the action of the working head, but the crack width should be limited. Since concrete has exceeded the stage of linear elasticity, the application of nonlinear finite element method is imperative.
Catalog of Stainless Steel Lounge Chair from Shenzhen Yadea factory. We manufacture high quality stainless steel Lounge Chair with leather or fabric upholstery. The stainless steel lounge chairs are available in polished finish or brushed finish. Both finish of the stainless steel lounge chair look beautiful and luxury. The stainless steel lounge chair is also with modern elements and environment-friendly.
Stainless Steel Lounge Chair
Stainless Steel Lounge Chair,Lounge Stainless Steel Modern Chair,Stainless Steel Portable Lounge Chair,Stainless Steel Beach Lounge Chair
DELO SOFA , https://www.modernluxuryfurniture.com