Force Analysis Diagram of Container House

The force analysis of container houses should focus on the synergistic effect between the corrugated plates and the frame, and their force characteristics can be systematically analyzed through methods such as structural simplification, material equivalence, and finite element simulation.

1. Core Mechanism of Action of Corrugated Plates

The corrugated plates of container houses are made of 2mm or 1.6mm thick steel plates, forming an orthotropic structure through the corrugated shape. Their force characteristics are as follows:

1. Perpendicular to the corrugation direction (E1): The corrugations are prone to out-of-plane deformation, and the equivalent elastic modulus is only 5% of the true value of steel. The local buckling critical load of the corrugations needs to be determined through finite element analysis.
2. Parallel to the corrugation direction (E2): The in-plane tensile and compressive properties are close to those of steel. Due to the presence of corrugations, the actual plate length increases by 6.5%, and the equivalent elastic modulus E2 = 1.065Es (where Es is the elastic modulus of steel).
3. Shear modulus (G12): The shear stiffness in the directions perpendicular and parallel to the corrugations differs significantly, and a smaller value needs to be used for equivalence to avoid structural instability caused by shear deformation.

2. Synergistic Force Model between the Frame and Corrugated Plates

The container frame is composed of thin steel tubes with a side length of 60mm, such as corner posts, bottom side beams, and top side beams, and its force needs to be analyzed in conjunction with the corrugated plates:

1. Diaphragm effect: The corrugated plates, as the covering layer, are connected to the frame through corner fittings, forming an overall force system. Under horizontal loads, the corrugated plates provide lateral stiffness and reduce the lateral displacement of the frame.
2. Impact of openings: If there are openings on the side of the container (such as the opening on the south side in the case study), the stiffness of the corrugated plates needs to be reduced. When the opening ratio exceeds 30%, the lateral stiffness may decrease by more than 50%, and the remaining stiffness needs to be simulated through equivalent cross braces.
3. Vertical load-bearing: The corrugated plates are connected to the frame through the peaks of the corrugations and can transfer vertical loads to the corner posts and bottom cross beams. The vertical load-bearing capacity of the corrugated plates of a single 40-foot container can reach 45 tons (standard value).

3. Finite Element Simulation and Simplification Methods

1. Finite element modeling: Shell elements are used to simulate the corrugated plates, and the mesh size is controlled within 100mm. Beam elements are used for the frame, and rigid connections are used to simulate the connection between the corner fittings and the corrugated plates.
2. Equivalent simulation: The corrugated plates are simplified as cross braces, and the cross-sectional area of the braces is calculated according to the principle of stiffness equivalence. The vertical load-bearing capacity of the corrugations is simulated through two-end hinged columns, and the principle of area equivalence ensures the accuracy of load transfer.
3. Seismic design: According to the "Steel Structure Design Standard" (GB 50017—2017), the approach of high load-bearing capacity and low ductility is adopted, the width-to-thickness ratio limits of members are relaxed, and structural safety is ensured through minor and moderate earthquake verifications. For example, the maximum inter-story displacement angle of a double-story container fire station needs to be controlled within 1/527.