Project Research Of Detection And Maintenance On BeiDa Bridge In DaLian

Detection and maintenance after the operating are the key point to extend the useful life of cable suspension bridge. Detection is the most primary method to know whether the bridge is running good now or not, its result can be used to assess the bridge synthetically and provide advantageous and direct base for confirming the maintenance project; Maintenance is the method to deal with detection result. Based on the method of modern cable suspension bridge, infinite element, random vibration, vibration testing and analysis technology, this paper studies and designs the detection and maintenance project of BeiDa Bridge by summarizing the method of detection and maintenance of some concerned bridges. Idiographic steps are actualized as followed.1. The bridge is detected ectally and the actuality of the bridge is known.2. BeiDa Bridge is surveyed under dead load, the survey result is analysed, the exact estimate of geometrical state and state under force when the bridge is under dead load is confirmed.3. Through the theoretical analysis of BeiDa Bridge, this paper makes sure the controlling load and loading case under the condition of ensuring the load test efficiency. According to the results of comparison between the actual value and the theoretical value of the controlling section this paper makes clear the checkout coefficient and then confirms the actual carrying capacity of bridge.4. The problem of bridge vibration is very complicated and the analysis in theory still can not meet the requirement of the engineering application. In order to test the actual condition when the bridge is forced by dynamical load, running test, braking test and jumping test are carried out respectively. According to the time-travel curve under the cases above-mentioned, the actual figure of impact coefficient comes out .At the same time this paper compares it with both actual values which are got before and that in theory and brings forward beneficial advices for the road managing and maintaining department.5. Theoretical mode analysis is made by establishing the dimensional dynamic infinite element model of BeiDa Bridge with Midas software, thus natural vibration frequency and mode shape of BeiDa Bridge theoretically are concluded. With pulsation measurement method this paper tests the actual mode parameters (including mode shape and natural vibration frequency). The comparison among actual results, older actual results and those in theory indicates that this bridge is qualified with satisfactory dynamical peculiarity, the dynamical peculiarity is almost the same as when it was just established. Furthermore this paper analyses the causes that these mode shape lie in according to the structure characteristic of BeiDa Bridge.6. According the actual results and those in theory, this paper confirms the maintenance project of the bridge. Through discussing with professionalcorporation and studying fore data, the project about main cable protection and bar preservation which is feat to BeiDa Bridge is set down. According to the studying result of cable suspension bridge got by others before, the conclusion is that the bridge is a conservative system, the adjusting from actual state to needed state has nothing to do with the path. Thus, any construction program can carry its point when the extension value of hanger is confirmed and the bridge is safe. The difficulty of execution control is reduced very much. Based on this, the method of stretch leapfrogging is put forward, stretch step size is reduced and the safety of bridge can be ensured during the construction without increasing construction difficulty and duration.