Design steps and design ideas of workshop steel structure

1. Determine whether the structure is suitable for steel structure and high temperature workshop

Structures with high sealing requirements, requiring movement or frequent disassembly and assembly. Intuitively, buildings, stadiums, opera houses, bridges, TV towers, warehouses, factories, residences and temporary structures, etc. This is consistent with the characteristics of the steel structure itself.

2. Structure selection and layout

This is just a brief introduction. Please refer to relevant professional books for details. Because the structure selection involves a wide range, the structure selection and arrangement should be carried out under the guidance of experienced engineers.

The whole process of workshop steel structure design should emphasize "conceptual design", which is particularly important in the stage of structure selection and layout. For some problems that are difficult to be accurately and reasonably analyzed or not specified in the specification, the layout of the control structure can be determined from a global perspective based on the following mechanical relationships, failure mechanisms, earthquake damage, experimental phenomena and design ideas of the overall structural system and subsystems. and detailed measures. Conceptual design allows for quick and efficient ideation, comparison and selection at an early stage. The obtained structural solutions are often easy to calculate manually, with clear concepts and correct characterization, which can avoid unnecessary complex operations in the structural analysis stage. At the same time, it is also the main basis for judging whether the output data of computer internal force analysis is reliable.

Steel structures usually include frame, plane (wood row) frame, grid (shell), cable-membrane, light steel, tower mast and other structural types. Most of its theories and technologies are mature. There are still some problems that have not been solved, or there is no simple and practical design method, such as the stability of the reticulated shell.

When choosing a structure, its different characteristics should be considered. In the light steel industrial workshop, when there is a large suspended load or moving load, it can be considered to abandon the portal rigid frame and use the grid frame. In areas with high snow pressure, the roof curve should favor snowfall (50° relative to the snow load). Similar considerations apply to areas with high rainfall.

Where construction permits, it may be more economical to arrange bracing in the frame than a simple frame with rigid joints. In buildings with large roof covering spans, a suspension cable or cable-membrane structure system in which the components are mainly in tension can be selected. In the design of high-rise steel structures, steel-concrete composite structures are often used. In high-rise buildings with high seismic intensity or very irregularities, unfavorable seismic core tubes and frames should not be selected purely for economic reasons. Giant SRC columns should be selected for the periphery, and the core is the structural system supporting the frame.

The layout of the workshop steel structure should be comprehensively considered according to the system characteristics, load distribution and properties. Generally speaking, the stiffness should be uniform and the mechanical model should be clear. Try to limit the influence of large or moving loads and choose a direct route. The distribution of lateral supports between columns should be uniform, and the center of mass should be as close as possible to the action line of the lateral force (wind shock). Otherwise, twisting of the structure should be considered. The lateral resistance of the steel structure should have multiple lines of defense. Supporting the frame structure, the columns should be able to bear at least 1/4 of the total horizontal force alone.

The secondary beam arrangement on the frame structure plan, and sometimes the load transfer direction can be adjusted to meet different requirements. Usually, the secondary beams are arranged in the short direction to reduce the section, but this will increase the section of the main beam and reduce the storey height. On shorter primary beams, secondary beams can be sacrificed to preserve primary beams and columns.

3. Estimating the Section

After the structural arrangement is completed, a preliminary estimate of the member cross-section is required. The main assumptions are about the cross-sectional shape and size of beams, columns, and supports. The steel beam can choose channel steel, rolled or welded H-beam section, etc. Section heights are usually chosen to be between 1/20 and 1/50 of the span, depending on the load and support conditions. When the flange width determines the l/b limit based on the spacing of the lateral bracing between the beams, the complex calculation of the overall stability of the steel beam can be avoided, and this method is popular. After the section height and flange width are determined, the plate thickness can be estimated according to the local stable construction regulations in the code.

4. Structural Analysis

In the actual design of the current steel structure, the structural analysis is usually a linear elastic analysis, and P-Δ and p-δ are considered when conditions permit. Some recent finite element analysis element software can partially take into account the geometric nonlinearity and elastic-plastic behavior of steel. This provides the conditions for a more accurate structural analysis. Simple structures are analyzed by hand calculations. Need to model complex structures, run programs, and do detailed structural analysis.

5. Engineering judgment

In order to use the structural software correctly, "engineering judgment" should also be performed on the output results. For example, the period in each direction, total shear force, deformation characteristics, etc. are evaluated. According to "engineering judgment", choose to modify the model to re-analyze, or modify the calculation results, different software will have different applicable conditions.