In recent years, prestressed concrete bridges have dominated the bridge type selection processes in Colorado. This can be attributed to a lack of steel mills combined with a strong presence of precast fabricators in the region. In addition, a lack of readily available economical and innovative procedures to design and construct steel bridges has hindered the industry in certain areas such as Colorado. During this research it was identified that designing steel girders as simply supported for the non composite dead loads and continuous for composite dead loads and live loads would provide economy. A preliminary girder selection software was created using this design procedure. The software takes user inputted data, such as span length, width, number of girders along with various other design inputs, and displays the lightest wide flange beam size that would support the loads using AASHTO LRFD Design Specifications. Using the girder selection software, design charts and tables were created to outline structural steel weight to span length and number of girders. The design charts will aid the bridge type selection process by giving designers an accurate measurement of minimum steel requirements for numerous one, two, and three span steel bridges.
This study applies contract bid tabulations and element-level condition records to develop element-level actions, costs for actions, transition probabilities for models of deterioration of bridge elements, and transition probabilities for improvements to elements due to actions. The study uses transition probabilities for element deterioration to compute the number of years to possible loss of safety in bridges, and to compute the number of years for inspection intervals. It examines variations in costs of actions and deterioration of elements among CDOT regions.
This study evaluates the strength and long-term performance of CFRP prestressed panels in a bridge deck, compare the behavior of bridge decks designed with the empirical and conventional methods of AASHTO, and a new limit-state design, and examinne the influence of lap splices between precast panels on deck cracking.
Bridge decks deteriorate faster and require more maintenance and repair than any other structural components on highway bridges. Topical protection systems act as barriers to protect bridge decks from corrosion damage by preventing water, oxygen, and chloride ions from reaching the reinforcement. This study evaluated topical protection systems commonly used on highway bridge decks in Colorado, including low-permeability concrete overlays and waterproof membranes with asphalt overlays.
This report provides a comprehensive literature survey of permanent and temporary deterrents to nesting and roosting, a discussion of risks to human health and safety from exposure to bird nests and droppings and recommended protective measures, and the results of a multi-year field study to test temporary nesting deterrents judged to be most effective.
