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Current Bridge Health Index (BHI) in Pontis Bridge Management System applied to assess the bridge health conditions for 615 bridges in city and county of Denver (CCD) does not provide CCD engineers a valuable analysis of the health condition of its relatively small bridge network. This paper explores both the calculation results and the computing methodology of the current BHI. The BHI was computed for the entire 615 CCD bridge network using the two current cost-based methodologies. Based on the analysis, it was concluded that the current BHI is subjective to a municipality's often imprecise cost data. This coupled with the methodology of heavily correlating cost with a bridge's condition reveals potential for modification to meet the needs of the CCD. The results of this study are used as a basis for developing an alternate BHI methodology. [ABSTRACT FROM AUTHOR]

High mast lighting structures are being used to provide illumination for large intersections, particularly for highways located in rural areas. These structures, ranging from approximately 15–40 m(50–130 ft) in height, are exposed to high wind forces that in turn produce a tremendous number of loading cycles each year. A recent high mast lighting structural support failure in the high plains of Colorado near Denver International Airport provided the impetus for this study. These high-mast structures are less than one meter (3.28 ft) in diameter and are quite flexible relative to many civil engineering structures. This flexibility results in large deformations when compared to their diameter, i.e., when combined with the height of these structures. Furthermore, large forces and moments at the base are produced that result in large stresses and stress reversals during multimode excitation. This paper presents the process and results for the development of a reliability-based design procedure for high-mast lighting structural supports based on fatigue life. The resulting procedure is prescriptive in that a series of design charts result from full nonlinear finite element analysis. The loading on the slender body is characterized by Morison’s equation, essentially providing the nonlinear loading relationship for the wind on the moving structure. Then, a well-known random vibrations approach was coupled with Miner’s rule to estimate the fatigue life of the structural support. Several illustrative design examples are presented and shown to compare very well with full simulations. [ABSTRACT FROM AUTHOR]

The City and County of Denver (CCD) Public Works Department owns, inspects, and maintains 531 bridges in its inventory of which 264 are considered major structures spanning over 6.1 m in length. In this paper, a methodology using the CCD major bridge network for the application of nondestructive evaluation (NDE) methods in bridge inspections is explained. The methodology, called Bridge Evaluation using Nondestructive Testing (BENT) helps systematically integrate NDE methods and conventional bridge management systems by using a Markovian deterioration model. Although the BENT method can be applied to timber, steel, and concrete bridges, in this paper the application of the method will be restricted to concrete bridges. The BENT system is part of a comprehensive geographic information system whereby database queries can be completed using a map interface. The database contains a wide array of information in the CCD infrastructure inventory including bridges, pavements, alleys, and street subsystems. [ABSTRACT FROM AUTHOR]

Current bridge health index (BHI) in Pontis bridge management system applied to assess the bridge health conditions for 615 bridges in the city and county of Denver (CCD) does not provide CCD engineers a valuable analysis of the health condition of its relatively small bridge network. Both the calculation results and the computing methodology of the current BHI reveal that it is subjective to a municipality's often imprecise cost data. This paper focuses on developing an alternate BHI. In order to understand the principle and procedure of the BHI calculation, the element weighting point was developed as a new concept in the analysis. The study concluded that the weighting point should reflect the effect of element damage on bridge health and function instead of a percentage of element value. Based on this conclusion, the current BHI was modified. The Denver BHI, a new diagnostic tool, was developed. It has already been adopted in the Pontis bridge management system of the CCD public works department. [ABSTRACT FROM AUTHOR]

Nondestructive testing techniques have been historically and commonly used to evaluate the quality of existing concrete structures. Several traditional nondestructive testing techniques were applied to the pier caps of the Quebec Street Bridge over Air Lawn Road, constructed in 1971, which is located in Denver, Colorado. The techniques utilized included visual inspection, hammer sounding, Schmidt hammer rebounding, and ultrasonic pulse velocity testing, including tomographic imaging. Results of the nondestructive tests were used to determine areas to be tested with local destructive tests. These tests included concrete compressive strengths, chloride testing, and petrographic testing. This paper presents the application and interpretation of common nondestructive testing techniques and the consequent repair, rehabilitation, and maintenance decisions. The overall results indicate that inside cores of all the pier caps are healthy, sound concrete. On all of the pier caps, extensive exterior concrete layer rehabilitation needed to be completed. [ABSTRACT FROM AUTHOR]

The City and County of Denver (CCD) and the University of Colorado Denver have been involved in cooperative research since 1997. Although a variety of projects have been completed, the main deliverable has been a comprehensive geographic information system database containing both major and minor infrastructure. Major infrastructure includes assets such as bridges and streets, while minor infrastructure includes alleys and street subsystems, such as curbs, gutters, inlets, sidewalks, driveways, cross-pans, and handicap ramps. This paper presents the equipment, methodology, results, and applications based on the inventory and analysis of the CCD’s concrete curb and gutter infrastructure. In summary, approximately 3,300 lineal mi (5,280 km) of curb and gutter were inventoried and inspected over a period of three years at a cost to the CCD of approximately $100 per mile. [ABSTRACT FROM AUTHOR]

This paper presents the procedure and results of a strain gauge study completed on the eastbound 6th Avenue Viaduct in Denver. The 6th Avenue Viaduct was modified in a 1997–1998 rehabilitation, making the entire superstructure continuous. New sliding bearing pads failed to properly accommodate expansion and contraction of the bridge superstructure due to temperature changes. Visible damage due to contraction of the superstructure in the winter of 1999–2000 prompted a study of substructure elements to determine the short-term safety and long-term viability of the bridge. Substructure elements were instrumented with a total of 62 strain gauges and two concrete crack gauges. Data were taken for a period of 3 months. Analysis of the data suggests that the bridge is safe for short-term use, but that the long-term viability of the structure has been compromised. Repair or replacement of substructure elements is recommended, along with frequent monitoring during the interim period. [ABSTRACT FROM AUTHOR]

The objective is to examine the performance of specific detailing components of mechanically stabilized Earth (MSE) walls when subjected to midlevel seismic excitations, such as those expected in the State of Colorado. The motivation for this study is the elevated peak ground accelerations mandated by the 2007 4th Edition of AASHTO LRFD bridge design specifications. According to this revision, highway-related projects must be designed for an elevated 1,000-year return period earthquake, as opposed to the earlier editions' 500-year return period earthquake. Finite-element analyses are performed using LS-DYNA to examine the displacement-based, dynamic behavior of individual MSE wall components, such as geogrid reinforcement and wall facings. Walls at two heights, 4.57 m (15.0 ft) and 9.14 m (30.0 ft), with two types of facings (modular block and segmental panel walls), reinforced using geogrids, are modeled based on the Colorado Department of Transportation drawings. These walls are subjected to three synthetic earthquake motions generated by the USGS 2002 deaggregation tool for three sites spread across the geographical extent of the State of Colorado. The results show that typical MSE walls perform well with respect to connection details when subjected to midlevel seismic loads. [ABSTRACT FROM AUTHOR]