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Wu F.,Hunan University | Liu B.,Hunan University | Deng L.,Hunan University | Deng L.,Hunan Gaoling Construction Group Stock Ltd Company | And 3 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2014

A new kind of composite hollow floor was proposed based on the combination of the advantage of cast-in-situ hollow floor and composite floor. Ten slab strips of hollow floor were tested under monotonic loading. The cross sections of specimens are 230 mm×500 mm and 300 mm×600 mm, which were classified into two types by the precast panel with or without longitudinal rib and a cast-in-situ hollow specimen to investigate the failure mode, monolithic action of the entire cross section, positive flexural strengths of normal section and short-term stiffness, and the horizontal shear performance, etc. The results indicate that composite hollow slab and the cast-in-situ hollow slab show the same mechanical characteristics and deformation characteristics from being loaded to failure. The calculated values of cracking moment, ultimate bending moment, and average crack interval for composite hollow slab, which is calculated using I-shaped cross-section of the weakest flange in the tube filler, agree well with testing values. For the present investigation conditions, the change of the arrangement methods and diameter of the tube filler has not caused cracks and slip problems in lamination but weakened the tension stiffening in the specimens to varying degrees, so that the short-term stiffness after cracking is suggested as a cracking stiffness of controlling section. By comparing the calculated values of the tube filler spacing and the flange thickness to real size of the flange with the actual identical size of the floor, the shear strength of the lamination may ensure the safety and use of the real projects according to the force analysis of the lamination. The overall mechanical properties of the two types of composite hollow slabs are similar to those of the cast-in-situ hollow slabs, and can meet the engineering design requirement. ©, 2014, Science Press. All right reserved.

Wu F.,Hunan University | Li J.,Hunan University | Zhou X.,Hunan University | Zhou X.,Chongqing University | And 4 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2014

Traditional cast-in-place concrete hollow floor still has problems such as small shell stiffness, high production costs, low recycling rates and complex anti-floating measures. To solve the problems, a new-type after-loading hollow-ribbed floor was invented. In order to understand the behavior of mechanical performance and failure mode of this new-type floor under vertical load, a large scale slab specimen under short-term static load has been tested. Performance of the specimen under vertical load was evaluated in terms of crack and failure mode, flexural deformation, stress-strain laws, vertical bearing capacity and the working performance of the precast slab in the floor structure. The result shows that the new-type floor has high vertical bearing capacity, bending stiffness and good integrity, the precast slab has a good working performance in the new-type floor structure, and the deformation and crack of this new-type floor have similar characteristics with two-way slab and solid flat slab. Through the existing calculation method for deflection of elastic theory of two-way slab supported by corner columns, and considering the structure layout and load method of this test floor, two simplified calculation methods were introduced considering the deformation of elasto-plastic phase, and the calculation results agree well with the test results. ©, 2014, Science Press. All right reserved.

Wu F.-B.,Hunan University | Huang H.-L.,Hunan University | Chen W.,Hunan University | Chen W.,Hunan Gaoling Construction Group Stock Ltd Company | And 2 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Mechanical behaviors in construction phase of PPCRP (Precast prestressed concrete ribbed panels) relate to distributions of preformed holes in the rib. For the convenience of industrialized production and site operation, the specification design is discussed. The general formulas of flexural deflections are deduced, taking into account the distributions of preformed holes in the rib and equivalent rigidity formulas for PPCRP, which are easy to program with MATLAB. The contrast analysis among the inverted camber and remaining camber under dead weight and deflection in construction stage with 5 different distributions of preformed holes is conducted, and the result shows that preformed hole distributions have an obvious effect on the deflections, which decreases with the increase of length of PPCRP. It is suggested that inverted camber can take the average of the deflection calculated by a solid rib model and a through-holes rib model, and the remaining camber under dead weight and deflection in the construction stage can be calculated by the through-holes rib model.

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