Basement restaurant design specifications
Seismic requirements
Basement if not properly designed, the overall seismic performance will have a greater impact, according to the Nanjing Construction Drawing Review Points, for the semi-basement depth requirements should be greater than the height of the basement above ground level in order to disregard the number of floors, the total height can only be counted from the outdoor ground. The wall columns of the basement and the wall columns of the superstructure should be harmonized. Basement roof indoor and outdoor plate elevation changes, when the elevation change exceeds the beam height range is the formation of the wrong layer, no measures should not be taken as a superstructure embedded parts, the specification specifies that as a superstructure embedded parts of the basement floors of the top floor cover should be used as a beam and plate structure, the basement roof for the roof of the floor cover should not be used as a superstructure embedded parts. Structural calculations should be down to meet the embedded end of the requirements of the basement floor or floor, but the bottom of the shear wall to strengthen the number of layers should be counted up from the ground, and should include the subterranean floor.
Load value and combination
Basement wall bending and shear calculations, earth pressure caused by the effect of permanent load effect, variable load effect control of the combination of earth pressure load sub-coefficient of 1.2; permanent load effect control of the combination of the load sub-coefficient of 1.35. For the live load on the ground, should be multiplied by the same side pressure coefficient, many design calculations are not correct. Incorrect. Basement floor strength calculation, according to the "building structural load specification". Resistant to flotation calculations, the plate, the overburden of the weight of the load sub-coefficient should be taken as 0.9. Basement wall of the earth pressure should be static earth pressure, according to the different nature of the soil were used in different methods of calculation, cohesive soil using soil and water, sandy soil using soil and water sub-calculation.
Groundwater and anti-floating
Groundwater level and its amplitude is the basement anti-floating design is an important basis for the design of the actual basement anti-floating design is often only considered in the normal use of the limit state, the construction process and the flooding period of insufficient attention, which will result in the construction process due to the anti-floating is not enough to appear in localized damage. In addition, in practice, in the same overall large area of the basement on the construction of a number of high-rise and low-rise buildings, and the basement area is large, irregular shape, coupled with the local above the building is not, this kind of resistance to levitation is also relatively difficult to deal with, must be carefully analyzed and dealt with.
Cracks and control methods
Concrete in the basement wall is prone to shrinkage, constrained by the structure itself and the side walls of the pit, resulting in large tensile stresses until shrinkage cracks, the width of cracks in the basement wall is controlled to be within 0.2mm, and the amount of reinforcement tends to be controlled by the crack width calculation.
Many of the design of the project will be the basement waterproofing structural components of the calculation of the bending distance amplitude, some of the lower end of the articulated, some did not consider the load sub-coefficient, multi-storey is not calculated according to the continuous calculation of multi-span, basement wall in the calculation of the omission of the crack resistance, basement walls and basement slabs connected to the construction of the irrational, the building is not long enough to set up joints or stay after the pouring zone, after the pouring zone is improperly set the location of the outer wall construction joints or after the pouring zone, the construction joints or after the pouring zone details are not accounted for. The detailed drawings of the pouring zone are not accounted for, and the settlement joints are not set at the outdoor entrances connected with the main structure, which leads to the violation of the design specification and the leakage phenomenon. The basement of a project is designed as a large chassis, and the foundation form under the large chassis has natural foundation, pile foundation and rigid pile composite foundation at the same time, and this kind of foundation is only suitable for the construction stage even if the back pouring belt is set.
Protective layer and bedding thickness
"Waterproofing Technical Specification for Underground Engineering" (GB50108-2001) for waterproof concrete structure: the structure thickness should not be less than 250mm; crack width shall not be greater than 0.2mm, and shall not be through; the thickness of protective layer of reinforcing steel at the water surface should not be less than 50mm. waterproof concrete structure concrete bedding for the bottom slab, strength grade should not be less than C15, thickness should not be less than 50mm. Grade should not be less than C15, the thickness of not less than 100mm, in the weak soil layer should not be less than 150mm. engineering practice shows that if the structural thickness or the thickness of the protective layer of reinforcing steel at the surface of the water is often less than the normative limit is often the cause of water seepage and leakage phenomenon is a common cause of the specification was revised after the limit was increased accordingly, attention should be paid to.
The basement roof reinforcement should be strengthened, the protective layer and concrete bedding and strength level should be added according to the specification.
Basement design specification points mainly contains the above points. But the basement design specification is actually a lot of aspects of the requirements, if you want to know more, I would recommend that you go through the "Building Fire Code", "high-rise civil building fire code", "underground fire code for civil defense buildings," "Underground Defense Building Design Code" and other such norms, which is clear that the basement design specification.