Stress Spikes in Pin Hanger System of Newburgh-Beacon Bridges - A Case Study

摘要

Pin and hanger system of long span truss bridges have several functional problems, such as frozen pins, stress spikes in hangers, lack of expansion joint movements etc. It has been difficult to develop the pin and hanger retrofit strategy because the cause for the observed problems is usually unknown. This paper presents a study performed on pin and hanger system of one such bridge- the Newburgh Beacon bridge. Extensive field testing performed so far has failed to identify the cause for the observed stress spikes. The concept of misalignment loading is developed in this article to explain the observed behavior. Stress spikes predicted using this concept matched very well with the observed stress spikes. Finally, the use of misalignment loading to evaluate other truss members is also discussed.