Analysis on the key points of cost control of precast buildings
The bending moment and shear coefficient are enlarged and the quantities are increased.
Technical specification for cast concrete structures, Clause 8.1 Article 1 stipulates that for the assembled integral shear wall structure with both cast-in-situ shear wall legs and precast shear wall legs in the same floor, the horizontal seismic bending moment of cast-in-situ wall legs should be multiplied by an increase factor of not less than 1.1.
Internal partition strip, NO2.
Comparison of unit price between precast components and cast-in-situ components 1.
Concrete hollow slab should be used for laminated slab with slab thickness greater than 180mm.
Article 6.6 of technical specification for cast concrete structures Article 2: the laminated slab shall be designed according to the current national standard code for design of concrete structures (GB50010) and shall comply with the following provisions: 1.
Truss reinforced concrete composite slab should be used for composite slab with span greater than 3m; 4.
Comprehensive cost analysis case incremental cost analysis of precast components of a precast building project in South China Technical Specification for precast concrete structures (jgj1-2014) comparison of unit price of precast components with comprehensive unit price including tax of PC components: 1.
coordinate and review by multiple disciplines to minimize later modifications.
Conclusion 3: compared with the technical content, the comprehensive cost of manufacturing and installation of PC components is 2.2 times that of cast-in-place components due to the amplification of the coefficient required by the specification.
Prestressed concrete precast slab should be used for laminated slab with span greater than 6m; 5.
Conclusion 1: the comprehensive cost of linear components is greater than that of surface components, and the unit price of components is the highest in beam and the lowest in slab.
Precast building is the trend of the construction industry.
3.
Increased cost of cast-in-situ part: Article 6.3 of technical specification for precast concrete structures Article 1 stipulates that under various design conditions, the assembly structure can be analyzed by the same method as the cast-in-situ concrete structure.
In the construction stage, the construction unit shall formulate reasonable plans according to the characteristics of the project Construction scheme and construction plan.
According to the requirements of the regulations, the precast thickness of the laminated slab shall not be less than 60m, the thickness of the post cast concrete laminated layer shall not be less than 60m, the minimum thickness of the laminated + post cast part shall be 120mm, and the thickness of the traditional building floor slab is about 90100m.
More than 40 provinces and cities have issued relevant documents.
The quantity of concrete increases and the cost increases.
Increased cost of PC components: PC components have high reinforcement content, low formwork turnover rate, amortization cost of industrial production machinery, difficult transportation and installation and other factors, which lead to their cost being much higher than that of traditional cast-in-situ concrete components.
Sequence of installation cost of PC components: PC precast external shear wall (internal shear wall) > PC precast balcony slab > PC precast composite slab > PC precast air conditioning slab > PC precast composite beam (precast floating window) > PC precast stairs.
The cost person needs to find ways to control the cost in the continuous industry reform.
Taking a precast construction project in South China as an example, this paper discusses the key points of precast construction cost control at this stage from the following aspects.
2.
According to the requirements of the specification, various coefficients of the cast-in-situ part of the precast building need to be enlarged, the quantity of reinforcement increases and the cost increases.
How to control the cost of the transformation from the old to the new is a matter of concern to everyone.
Analyze and increase the cost in terms of design cost in the design stage, material cost and machinery cost in the construction process.
The highest comprehensive unit price of PC components is PC precast composite beam, PC precast balcony slab and PC precast external shear wall, and the lowest is PC precast composite plate and PC precast staircase.
During the construction process, the cost shall timely follow up the project progress and make corrections.
Ranking of main material cost of PC components: PC precast composite beam > PC precast staircase > PC precast balcony slab > PC precast air conditioning board > PC precast floating window > PC precast external shear wall > PC precast composite plate > PC precast internal shear wall (the ranking will fluctuate according to the change of component content).
Comprehensive analysis of incremental cost.
Cost estimation.
Only in this way can he keep pace with the times and better reflect the value of the cost person-.
The key points of cost control of tonsen precast buildings at the land acquisition stage mainly know the preferential and incentive policies of various local governments for precast buildings, These can make up for the increase of costs to a certain extent (for example, local preferential policies, the main structure of the project can be pre sold when it is ± 0.00).
In the design stage a, select the most economical assembly scheme (choose more horizontal members and less or no vertical members); B.
Low area configuration (loft office and apartment) non residential 1 scheme is selected for the precast building scheme: No1.
2.
During component deepening, PC precast composite beam shall be used less and PC precast composite plate shall be used more.
With the continuous development of the construction industry, precast building is the future development trend.
the standard unit can be copied to the scheme of the next project; C.
High area configuration (talent, business apartment) residential 1 scheme: No1.
Reinforced truss floor support plate, PC stair components, wall column aluminum formwork and external thermal insulation rock wool board.
Unit curtain wall, wall column, floor slab, stair aluminum mold, PC household wall components and external thermal insulation rock wool board.
The thickness of precast slab of laminated slab shall not be less than 60mm, and the thickness of post cast concrete laminated layer shall not be less than 60mm; 2.
Conclusion 2: the precast building scheme should choose more horizontal components and less or no vertical components.
When the precast slab of the laminated slab adopts hollow slab, the cavity at the slab end shall be blocked; 3.
Unit curtain wall, NO3.
When there are both precast and cast-in-situ lateral force resisting members in the same floor, the bending moment and shear force of cast-in-situ lateral force resisting members under earthquake shall be appropriately enlarged under seismic design conditions, the bending moment and shear coefficient shall be enlarged, and the quantities shall be increased.