Research On The Applicability Of Large-cantilevered Pier Caps Bridge During Operational Period

In urban bridge building，the application of large-cantilevered pier cap is increasing.Large-cantilevered pier cap is often collocated with streamlined bridge pier, making the pierwith smooth lines, and novel modelling. Due to the large cantilever structure, the system ofinternal stress is complex. The calculation analysis and design method have not yet been fullyunderstood and effectively used. In-depth discussion and research application of this kind ofstructure has certain realistic and economic significance.At the same time, along with the rapid development of social economy, the vehicle modelshave become increasingly complex, and have a tendency of large overloading. Many of thelarge and heavy vehicles on road are far more than the existing bridge design load level, thespecification based on previous traffic load standard cannot represent the overloading ofspecial road section traffic loads.In view of the novel form structure, this article does research on bridge safety under thedesign load and the overloading load. Based on survey data from fort XuanPing, statisticalanalysis has been done to get various parameters of vehicle load. The vehicle probabilitydistribution of each motor model had been obtained, calculated and analyzed the effect valueof bridge under the existing survey load. Under the design level and survey overloading load,we calculated the bearing capacity factor of capping beam, identified the mostdisadvantageous section of each capping beam, and the stress state of capping beam had beenanalyzed. Based on the analysis of Midas Civil and MIDAS FEA, putted forward the safetycoefficient of bearing capacity and the most disadvantageous section stress reserves can beused as safety evaluation index of each type of capping beam.Midas Civil model calculation results show that the Y type pier capping beam safetycoefficient is greater than the vertical piers ones. Each type of cap beam safety factor underthe design level are in high level; Under the heavy vehicle load, Y type pier cap beam still hasa high safety coefficient, and the safety factor of the vertical pier cap is still greater than1, butthe quantity is relatively small. The most disadvantageous section for the Y type and vertical pier cap beam is both located in a zone of pier girder consolidation, but in a slightly differentposition. Under the two kinds of operating vehicle load, the corresponding section all havecertain compressive stress reserve, including the vertical pier cap beam’s minimumcompressive results under heavy load, which is-2.55MPa calculated by Midas Civil model,and-4.01MPa calculated by MIDAS FEA model.Analyzing the evaluation index of typical large-cantilevered pier caps, it indicates that allthe types of large-cantilevered beams meet the applicability requirements under the designload and heavy load.