Flexural Strength Reinforced Mechanism And Micro-mechanism Analysis Of LSFRC

Fiber reinforced concrete is a kind of heterogeneous material, which mechanical properties not only rest with the performance of component material, but micro-structure characteristic of material. Along with the extensive use of fiber reinforced concrete, designing and improving the material characteristic and mechanical properties of composite become the aim which engineer run after gradually. Nowadays' study on fiber reinforced composite is deepening into interface micro-structure interface effect and the relation between micro-structure and macro-properties, etc, in this dissertation, the primary coverage has been accomplished is expatiating the reinforced and toughened mechanism of fiber reinforced composite on a micro scale and the relation between micro-structure and macro-properties theoretically.Layer Steel Fiber Reinforced Concrete (LSFRC), which is on the basis of considering economy and improvement of material properties, letting steel fiber layer distributing layer by layer, and steel fibers are scattered to the upper and lower layer, concrete which is cast by this method, is called LSFRC. Our researchers have accomplished lots of test since 1997, it is indicated that LSFRC is provided with excellent properties on multi-aspect, such as: flexural strength fatigue resistance crack resistance durability, etc. Studying its reinforced mechanical essence absolutely and expounding its reinforced mechanism theoretically is the premise of this new composite material becoming extensive use.Based on all kinds of tests, some parameters which effected the properties of LSFRC were analyzed(elastic constant, geometric parameters, bonding condition, etc) system-atically. In micro-mechanics analysis, concentric column model and superimposed model were chosen, which considered the dimension of fiber and matrix, bonding condition, and the fiber distributing direction, etc, numerical analysis was carried out about the process of steel fiber pull-out from matrix, then, steel fiber pull-out load- displacement curve was obtained. Finally, considering the effect of the length of fiber burying on the fracture surface and direction coefficient, the "negative" stress intensity factor because of the distributing steel fiber was calculated, which could numerical reflect on macro flexural strength of specimen.