Technical And Economic Analysis On Unbonded Prestressed Concrete Flat Slab Floor

Prestressed reinforced concrete is based on the elastic recoil force of the pretighten high-strength steel, and then the concrete is imposed by a prestress, so the concrete can work in the most appropriate stress condition. Because the prestress can improve the mechanic performance of the concrete members and bring fine economic and social benefits, it is worth the advanced study. With the constantly development of the research of the prestressed structures, the properties and the theory of unbonded prestressed floor are improved, the same as the design methods are mature gradually. Along with the socio-economic development, the unbonded prestressed reinforced concrete structure is more and more widely used in the high-rise buildings and the large-span floor slab structures. In order to find out the techno-economic performance of the unbonded prestressed reinforced concrete floor, and what factors influence it, and the degree that they influence it, it needs to consider the design, the construction and the usability carefully. The techno-economic analysis of the unbonded prestressed reinforced concrete flat slab floor is made in this paper, the main works are as follows:1. The three important factors are slab span, load level, prestress value Np. In this paper, a 4×3 floor is chosen as the calculate unit. By adjusting the span, the load level and the prestress value Np, the thickness of the floor and the area of the bars are calculated. From the consumption of the concrete, the steel and the cost per unit area, the impact of the three factors on the unbonded prestressed reinforced concrete flat slab floor is analyzed.2. The market price of labor, material and machine is fluctuating with the relationship of the supply and demand, and it has a direct impact on the economic performance of unbonded prestressed floor. It is analyzed by the sensitive method that the influence of the price fluctuations of the concrete, the ordinary steel and the prestressed steel on the unbonded prestressed reinforced concrete floor.3. There are many forms of the floor structure, so that there must be a reference for choice. In this paper, the comprehensive evaluation system is put forward. The design of comprehensive evaluation system is following SMART guidelines, which includes specific, measurable, attainable, relevant and traceable. In the evaluation system of the floor, the impact of the different assessment of the principal (the owner, the designer, the construction side) on the indicator system building is analyzed at first; and then it is analyzed on the basis of the floor's own techno-economic properties that the indicators of the structure, the usage, the social economy, the construction as well as the risk. The weight of each indicator is determined using the analytic hierarchy process (AHP). Through the establishment of the hierarchy structure model and the judging matrix, the weights can be calculated and the consistency check should be made.4. The paper presents an analysis of the techno-economic performance of the unbonded prestressed reinforced concrete flat slab floor with an actual project. Two forms of structures are designed. One is the ordinary reinforced concrete flat slab floor and the other is the unbonded prestressed reinforced concrete flat slab floor. Their techno-economic performances are compared using the comprehensive evaluation system.