Structure design guidelines for commercial complexes?

Commercial Complex Structural Design Guidelines

1. Structural Design Basis

1. Basic Structural Design Parameters

Safety Level of Building Structures It is Class II with a design service life of 50 years. The values ??of parameters such as seismic fortification category, seismic fortification intensity, basic acceleration, basic wind and snow pressure, ground roughness category, construction site category, etc. should meet the basic requirements of the code or the special consultation report approved by the competent department, and it is not appropriate to raise the standards.

2. Dead load

The standard dead load values ??of roofs, floors, floors and building partitions are calculated based on the materials, wall thickness and decoration standards required in the architectural design brief. Sure. When calculating the wall load, attention should be paid to distinguishing between the bulk density of fire-resistant partition walls and ordinary lightweight partition walls.

For general parts, the reference load for floor construction is 2.5kN/m2; for the ice surface area of ??the ice rink, the floor construction load is 4kN/m2~5kN/m2; for the kitchen area of ??large and medium-sized restaurants, 4.0kN/m2, if not Depending on the specific location of the kitchen, the reserved kitchen area can be appropriately expanded.

In the design of construction drawings, corresponding loads should be reserved for the exterior facades (curtain walls, light boxes, LED screens). Special attention should be paid to the loads of glass curtain walls and stone curtain walls that should be determined according to the drawings.

3. Live load

(1) Commercial retail: 4.0kN/m2; first floor 5.0 kN/m2

(2) Cinema 3.5kN/m2 ; KTV, video games, ice rink: 4.0kN/m2 (3) Fitness center: 4.0kN/m2 (the water body in the swimming pool can be considered according to the constant load) (4) Catering: kitchen 4.0kN/m2, dining area 4.0kN/m2 (6) Bathroom 2.5kN/m2 (7) Fire staircase: 3.5kN/m2

(8) Supermarket live load reference value: fresh food area, grocery area, grain and oil area 10.0kN/m2, warehouse 15.0 kN/m2, 4kN/m2 in the rental area, 15kN/m2 in the receiving area, 7.0kN/m2 in the general area of ??the store, 20K N/m2 in the loading and unloading area

(9) Live load on the roof for people in: 3.0kN/m2, excluding the load of green covering soil and large equipment on the roof

4. Equipment load

The load value of the equipment room should be calculated and provided by the equipment professional based on the actual situation. Otherwise, the value can be determined according to the "National Technical Measures for Civil Building Structures". For HVAC equipment centrally placed on the roof, the structural design requires the equipment professional to provide corresponding information.

5. Fire truck load

The most unfavorable arrangement of the load and the stress diffusion of the cushion under the wheel should be considered, and converted into an equivalent uniform load. For foundation and crack control, only the normal use load is considered, and the fire truck load combination is considered when designing the strength of beams, columns, and floor slabs. When there is covering soil or other fillers on the structural plate, the wheel pressure of the fire truck needs to be reduced by considering the stress diffusion before acting on the structural beam plate. The load of the fire truck should be arranged in the most unfavorable arrangement according to the requirements of the specification to calculate the cross section and reinforcement of the beam plate. . Column, foundation design and crack width control do not consider fire truck load, but should meet the requirements of normal use load.

6. Other loads

The live load in the main atrium area can be appropriately increased to reserve the possibility for water features, large sculptures, etc. When a lightweight roof is used on the main atrium roof, a hanging load should be reserved. The value of the hanging load shall be subject to the recommendations of the promotion department. The load effects of large-diameter water pipes suspended from the basement ceiling should be considered. Other loads not listed should be determined according to specifications.

2. Main materials

Steel bars

For strength-controlled stress-bearing steel bars (including longitudinal bars and stirrups), priority is given to HRB400 grade steel bars, to be standardized. As higher grade steel bars are given, higher strength grade steel bars can be used. Construction-controlled steel bars are available at comparable steel prices, using lower grade varieties to reduce costs.

Concrete

Except for vertical components, it is recommended that the underground part should not exceed C35. The highest concrete grade is recommended not to exceed C60. It is recommended to use micro-expansion concrete with a higher strength grade than the concrete in the corresponding component parts for the post-cast belt, and the rest shall be subject to calculation.

Bricks and Partition Walls

Partition walls with fire protection functions should be made of lightweight blocks that meet the requirements of the regulations. Generally, partition walls should be made of lightweight materials commonly used in the local area.

Shaped steel, steel plate, steel pipe

Using Q345B, Q235B

3. Key points of structural plan design

1. Preliminary calculation in the plan stage< /p>

At the planning stage, preliminary calculations should be made on the selected structural form. You should have an in-depth understanding of the detailed structure and highlight shapes of the architectural plan, and make reasonable suggestions for plans that may seriously affect the size and arrangement of structural components. At the same time, issues that can shorten the construction period and reduce the difficulty of construction should also be considered when designing the scheme.

2. Structural form selection

Comprehensive consideration of factors such as building height, earthquake level, site conditions, etc., compare frame structures, few-wall frames, frame shear walls and other structural forms, and select the best .

3. Principle of dividing permanent structural joints

It is not suitable to set permanent joints in the basement. Structural joints on the ground should be divided according to the division of business types. The length of the structural unit after the joints should not exceed 150 meters, and structural joints must not pass through the auditorium. Taking into account the economy of structural design, corresponding structural measures can be taken to appropriately reduce the number of structural joints.

4. Selection of column spacing

The selection of column spacing should ensure that the number of parking spaces in the basement is maximized. Under normal circumstances, exactly three or four should be installed between one span of columns. Parking spaces; the layout of pillars occupying parking spaces in underground garages should be carefully considered, and corresponding measures should be taken to eliminate the pillars.

5. Selection of frame beam section

The size of frame beam section should comprehensively consider factors such as floor height and economy, and choose the most reasonable size, such as 9.0m in the 6th and 7th degree zones. The frame beam section of the standard column network can be considered to be 300×700 to reduce stirrups. The cross-section of the secondary beam should be 250×550 to avoid setting structural waist bars.

6. Indoor active lines, atriums, and bridge structure plans

For cantilevered beams with a cantilever length less than 6 meters in this area, concrete structures are preferred, and the span-to-height ratio is not less than 5 controls. For cantilever beams greater than or equal to 6 meters, it is recommended to use steel-reinforced concrete components or steel structural components. The span-to-height ratio of continuous concrete beams in this area is controlled to be no less than 18. When ordinary beams cannot meet the design requirements, it is preferred to use one-way bonded prestressed concrete beams or profiled steel concrete beams.

7. Standard floor structure plan

It is recommended to use cross beams or parallel primary and secondary beam layout plans for boards with square grids. Parallel primary and secondary beam layout plans are preferred for boards with rectangular grids. Secondary beam layout.

8. Basement roof structure plan

The thickness of the basement roof is generally not less than 180mm. It requires a comprehensive economic comparison between the large plate structure and the beam plate structure to choose the best.

9. Basement floor structural form

The determination of the basement floor structural form should comprehensively consider factors such as base reaction force, foundation depth, foundation pit support, basement backfilling, etc., and select the most reasonable Bottom structure form. In general, it is recommended to give priority to beam raft and flat plate structures.

10. Sightseeing elevator design

The design of the sightseeing elevator is recommended to adopt a steel frame structure. The beam and column components can be rolled rectangular steel pipes or round steel pipes, and the connecting nodes should be directly butt welded. The main visual surface of the sightseeing elevator landing position should not be blocked by steel beams. The cross-sectional size of components should generally not exceed 200. When the overhang of the sightseeing elevator is too large, sightseeing ladder corner posts can be set up to control the height of the structure.

IV. Key points in the design of structural construction drawings

1. When designing construction drawings, we must consider reducing the complexity of construction and shortening the construction period.

2. The selection of pile type should be based on the use requirements of the building, the type of superstructure, load size and distribution, engineering geology, construction conditions and surrounding environment and other factors, and the best choice should be made. For projects that have the conditions to use post-grouting technology, the post-grouting method of bored piles should be considered to strengthen the pile end foundation.

3. In principle, there should be no concealed beams inside the raft and pile cap.

Since the raft and pile cap itself are very stiff, the shear bearing capacity is provided entirely by concrete. Concealed beam stirrups are not included in the calculation and are difficult to construct, so they are not recommended. Except for double pile cap.

4. Basement exterior wall reinforcement

The exterior wall of the basement of a commercial complex is generally longer. Considering factors such as crack resistance, full-length reinforcement should be used, and the steel bar layout should be fine. Way.

5. It is recommended to consider the beneficial role of foundation pit support when determining the earth pressure value of retaining walls.

When there are rigid piles or ground connection walls as the foundation pit support structure, consider Due to its beneficial effects, it is recommended to design exterior walls based on active earth pressure.

6. The basement roof should be given priority as the embedded end of the structure for calculation and analysis.

7. The self-weight of the pile should be considered in the anti-floating calculation, and it is recommended that all favorable loads be fully considered.

8. The possibility of early sealing should be considered when setting up the post-pouring belt in the basement, and this can be taken into consideration appropriately when designing the construction drawings.

9. Suggestions for dealing with over-long structures:

1) For floors with non-large plate structures, you can consider stretching the steel bars along the longer direction;

2) For large slab structures, part of the slab steel bars should be pulled through to resist the shrinkage deformation of the concrete; 3) It is not recommended to add fibers, expansion agents, and apply prestressing to the concrete. 10. The steel bars at the mid-span and lower supports of the upper part of the beam should not be arranged throughout the entire length. Cantilevered beams should adopt a variable cross-section design and should not adopt a horizontal haunch structure. 11. Adjust the eccentricity of beams and columns to avoid horizontal haunching of beams

When the eccentricity of beams and columns is greater than 1/4 of the column width, haunching is required according to the specifications. However, since the construction of horizontal haunching of beams is complicated, the design The eccentric distance of the beam should be adjusted to avoid it as much as possible. 12. Beam-column joints at the intersection of multiple beams should be designed with emphasis to ensure construction quality. Especially for beam-column joints with more than four intersecting beams, the steel bars at the column heads are too dense and the concrete is difficult to vibrate and compact, which can easily cause construction difficulties and safety issues. It is recommended to take the following measures:

1) The beams should be arranged continuously as much as possible or be extended by twice the anchoring length of the column end to avoid anchoring the beam steel bars into the column head;

2) Adjust the beams in this area individually The amplitude modulation coefficient can be considered to be in the range of 0.75~0.85;

3) The longitudinal steel bar nodes at the lower part of the beam can be processed without all extending into the support to reduce the overlap of steel bars in the column;

13. The control section of a frame beam is generally taken as the maximum bending moment at the two end column edges and the mid-span. The control internal force corresponding to the reinforcement of the column edge beam section should be the actual combined internal force of the column edge section.

14. Because the steel bars are denser in the embedded parts at the beam-column joints, the design of the embedded parts should consider the convenience and reliability of construction.

15. After the prestressed anchor head is sealed, it should not protrude from the outer edge of the structure. Structural beams and columns should reserve grooves for anchor head sealing, or extend the anchor head to the interior of the floor to seal the anchor. Avoid impact on buildings.

16. To give full play to the load-bearing capacity of the slab, minimize the layout of secondary beams

The design should consider minimizing the layout of secondary beams. For example, folding plates can be considered for partial lowering of the slab.

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There are generally no beams under the wall, and no side beams at the boundaries of small openings.

17. For conventional components, the requirements for economic reinforcement ratio of components should be considered: 0.3% to 0.8% for plates and 0.6% to 1.5% for beams.

18. The vertical members of the structure should change the cross-section and concrete strength according to factors such as axial compression ratio and lateral stiffness. The number of segments can be increased if conditions permit.

19. The structure of the daylight roof should give priority to meeting the functional and modeling needs of the building. It is recommended to use a steel structure that is easy to construct and light in weight.

20. The auditorium stands should be in the form of folding panels. The turning position should be designed according to the beam, and the thickness of the horizontal floor slab at the seating position is recommended to be 80mm. The frame columns under the grandstand should be raised to the grandstand floor, and frame beams perpendicular to the secondary beams of the grandstand should be arranged.

21. Focus on the requirements for structural embedded parts and reserved holes for generator rooms, large equipment, elevators, window cleaning machines, etc., especially the reserved holes for exterior walls and equipment installation.

22. If there are parts where mezzanines need to be added later, such as cable mezzanines, garage mezzanines, substations, etc., the reservation should be marked in the drawings.

23. The fireproof sealing area of ??commercial equipment tube wells is generally large, and it is recommended to consider specific methods in the construction drawings.

5. Key points for building functional control

1. The structural plan must meet the large space requirements of the shopping mall’s main entrance, atrium, cinema, ice rink, children’s experience city and other formats. At the same time, corresponding possibilities are reserved for interior decoration and business format changes according to the needs of the owners.

2. The column grid should be relatively regular to avoid extremely irregular column grids.

Pillars are not allowed to be placed in the main atrium of the shopping mall, above the ice rink, or in the cinema screening hall; pillars are not suitable to be placed at the main entrance of the shopping center, in the lobbies of cinemas, KTVs, and children's experience centers.

3. Concrete beams and slabs shall not appear directly under the glass roof of the atrium and lighting area; no exposed beams shall be allowed in the atrium void area.

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