Dynamic Characteristics Analysis Of Reinforced-concrete (RC) Simple Suppor Beam-bridge

It is still a very serious problem to accurately appraise the health condition and the load capacity of the reinforced-concrete beam-bridge. This problem is usual confronted with in practical engineering and has not been well solved yet. Static load test is a main method in testing ultimate load capacity of reinforced concrete. But there are many shortcomings of this method. Such as: This method exhausts too many manpower, material resources and time-, In order to get structure's load capacity, it will always been destroyed by exceeding static load. The price of this method is obvious. Another disadvantage of this method in some differential cases, this method cannot be successfully carried out. We need to break the traffic during the static test of the bridge. To general bridge, it needs break the traffic for 3 to 5 hours. Especially for those main traffic roads, we cannot image the traffic problem occurred by so long time of traffic breaking. So it is very necessary to study the theoretic method and technique of quick and effective determine RC structure ultimate load capacity by the way of dynamic test. Structure's dynamics respond under various stimulate is a kind measurement of its whole state. When the structure's characteristic of mass, rigidity and damp changed by its damage, the vibrate response will be changed either. And these changes can be accurate tested by vibrational test method. Native and foreign scholars have begun the study of this field by the early year of 1990s and have drawn many useful conclusions. The study of this paper is based on RC simple supported beam. Through the way of finite unit dynamics analyze and Matlab program, the mathematics model of simple-supported beam-bridge with attached load was built. Through the test of model beam, we build the relationship between characteristics of vibration with attached load and its damaged mode. RC beam's frequency change's regular with attached load was studied. Through alternate test of static load and dynamic load on RC beam, the frequency change disciplinarian from integrity to destroy of RC beam was studied. And built the mathematics model experiential formula between frequency and attached load, then to deduce the ultimate load capacity of RC beam, and realized quick evaluate RC beam load capacity. This paper brought forward a new technique of dynamic test condition and load capacity of reinforced-concrete beams.