Experimental Study On The Fatigue Performance Of Concrete Fabricated Hollow-ribbed Floor

The concrete fabricated hollow-ribbed floor, a new floor system, is composed of prefabricated hollow box and cast-in-place ribs. This floor has small thickness and weight, good integrality, it is appropriate for large-span structure, what’s more, convenient execution makes it easy for industrialized production. Based on these advantages, this floor was used in some regions in China. When this floor is applied to bridge deck slab, factory buildings or garage, these structures are under repeated load, what about the fatigue performance, and whether it has enough fatigue life under normal circumstances, these questions have an important meaning for structural safety. This thesis focused on fatigue performance under different amplitude of fatigue loading, the following were the main accomplishments:Five specimens of slab were designed and produced, they were the same. At first, a static test was made for one of the specimens, the phenomena and data were recorded, its ultimate capacity was the basis of fatigue loading. Fatigue tests were implemented for the other four specimens, under different amplitude of fatigue loading. Crack developing, degradation of stiffness and strength, strain behavior, failure patterns, fatigue life were recorded and compared with static test, the difference of fatigue performance under different fatigue loading was obtained.The fatigue properties of concrete and rebar, fatigue damage theory besides were introduced. According to measured load-deflection curves at mid-span, the evolution of fatigue stiffness based on measured deflection was established. The calculation method of remaining strength under static load was put forward, based on the change of constitutive relation of concrete and rebar.The stress amplitude of rebar was calculated, predicted value of fatigue life was obtained by S-N curves, it was close to test results.The forecasting method of fatigue life, based on cumulative fatigue damage theory, was studied. How the stiffness changed along with number of cyclic loading was calculated by method of average curvature and method of back-calculation on deflection, accordingly, the value of cumulative fatigue damage was deduced. The value of stiffness and damage before fatigue failure were confirmed initially, an idea about the implementation of this forecasting method was presented.