Research Of The Influence Of The Frame's Constrain To The Prestress

With the development of the prostressod concrete, it can he used in different building structure. For the requirement of architectural function,the partial span of structure is large, prestressed concrete must be used.More attention should be payed to the consequence of reinforced concrete to prestress when designing. This paper discussed the consequence of the constrain of reinforced concreteN creep and contraction of concrete and relaxation of reinforcing steel to prestress of three frame constructions. For discussing the area of cross section ., the ratio of reinforcing steel and the shape of prestressed re in forcement are all same. Finite-element program ANSYS was used to simulating the frames.DP material was used for concrete in simulating. The procedure of calculating is as follows:Establish the model of frame, the prestress was applied to frame as equivalent load which simulated the state of frame before the load applied on it.Calculated the loss of prestress with development of time. Apply the effective pro-stress of 3> 60 and 180 days after prestressing.Then apply the load on the frame simulating the structure in three load step.After analysing and calculating,the paper drew the conculsions as follows:The reinforced concret part of structure can lead the loss of prestress,the loss will increase with increasing of stiffness of constraint.The loss of prestross can bo calcualated approximately.With the development of time,the prestress decrease;With the increase of stiffness of constraint, the tendency of the decrease of prestress increases.