Analytical Study of the Long-Term Deflection in RC Beams & those strengthened with FRP

Fiber reinforced polymer (FRP) plates have gained popularity in the strengthening of reinforced concrete (RC) members due to the high strength to weight ratio, the ease of installation and low maintenance costs compared to other systems such as steelplates. Also, external bonding of fiber reinforced polymer (FRP) plate has been proven to be an effective method to strengthen and damage RC structures. However, not much attention has been given to the long-term behavioral aspects of FRP-strengthened RC members. It is difficult to accurately predict the long-term deflection, crack width and behavior of FRP-strengthened RC members. This study presents a method for predicting the deflections at any time of the service life of normal and high strength concrete structures, loaded at any age, creep coefficient and shrinkage strain and the participation of the compressive steel for RC beams, and for RC beams strengthened with FRP plates. The accurate prediction of deflections is a complex problem which requires the use of non-linear and time-dependent analytical methods. These methods are, in general, time consuming and require great effort[6-13]. However, at the design stage, simple but reliable methods which take into account the most important parameters influencing the long-term deflections may be very useful to adequately design the structure. For that purpose, many simplified methods have been developed [1-2-3-4-14]. Equations have been programmed to access the method combines the simplicity and accuracy and provides valuable information about the influence of each parameter on the increasing deflections with time. The analytical values are compared to the experimental results from some existing papers [8-9], and to the results obtained from ACI code [1]. It is found that the analytical method is in a good agreement with the experimental results from some existing papers [8-9].

Estimate The Static Fatigue Age For Springs Depending On Accelerated Tests

In this article we present a new and effective method to Estimate the static fatigue age for springs, when it works by static load or static strain for a long time at deferent temperature, this case is very important because the spring is a batteryfor force and it must save allow value of the force. At the first we present a theory study for “creep and relaxation “and how we can accelerate the test to get the results, then we suggest method to accelerate the test to know when the spring retch to the minimum allowable value of the force at work temperature degree, this method depend on tests at samples at deferent temperature degrees, higher than work and storage temperature, and then use the results to estimate the static fatigue age for springs at real storage and work temperature.