Development of a Steel Bridge System Simple for Dead Load and Continuous for Live Load. Volume 1: Analysis and Recommendations Final rept

摘要

A market analysis of bridge materials was completed, which indicated a declining trend in the use of steel girders over the last two decades. A new construction technique for steel girder bridges was developed to enhance their competitiveness in the short to medium span length range. In the new method, girders are placed on the supports as simple spans under construction loads. The continuity of the girders is obtained for traffic loads after hardening of the slab and diaphragm concrete through steel reinforcements. A cost-benefit analysis of two bridges constructed using the new method was completed. The study revealed that the cost and time of construction of the superstructure in each case was reduced by employing the new technique. Three possible connection details were proposed to complete the design of the new concept. In order to investigate the structural behavior of the proposed connections, a full-scale specimen of each type was designed, constructed and tested. In the first phase of testing, a cyclic load was applied to study the fatigue behavior. In the second phase, an ultimate load test was conducted to investigate the failure mechanism. To further study the structural behavior of the system, a series of finite element analyses was carried out and verified by the experimental testing results. Through these methods, the failure mode of each test specimen was identified. To explore the design capabilities of the new method, the mechanical behavior of the first and third specimens was described with a mathematical model. Design equations were then extracted from the simplified model and verified through finite element analyses.