Journal of Performance of Constructed Facilities

A performance function is the relationship between the bridge paint condition rating and time. This function reflects the level of service of the bridge paint. The performance functions of steel bridge paint for state structures maintained by the Indiana Department of Transportation (INDOT) were developed using both regression analysis and Markov chains. The regression and Markov models were used to predict the condition rating of a bridge’s paint at a given age. The probabilistic model that was developed with Markov chains was used to reflect the stochastic nature of bridge paint conditions. These deterministic and stochastic methods have been applied to the existing and the new bridges’ paint systems in INDOT structures. The existing paint systems are lead-based and zinc-vinyl. On the other hand, the new paint system is three-coat. The results indicate that both models are very efficient in representing the deterioration model for bridge paint systems based on historical data.

Life-cycle cost analysis was used to compare different alternative strategies for steel bridge paint systems. It was also used as a tool for steel bridge paint rehabilitation planning. The existing paint systems are lead-based and zinc-vinyl, while the new system is an inorganic/organic zinc, epoxy, and urethane paint system (three-coat). Economic analysis using present value (PV) and equivalent uniform annual cost (EUAC) was applied to compare several steel bridge paint system alternatives. The PV and EUAC were also used to compare different rehabilitation scenarios within the same alternative. Life-cycle cost analysis computations indicate that the three-coat paint system was better than others. Researchers concluded that the best scenario for three-cost system rehabilitation was doing spot repairs every 15 years of paint life. A maintenance plan based on life-cycle cost analysis also favored the “spot repairs every 15 years” scenario. A sensitivity analysis was also conducted to account for uncertainty in the cost, conditions, and subjective data.

Life-cycle cost analysis is an essential approach to differentiating alternative rehabilitation strategies for steel bridge paint systems. An economic analysis (EA), which is a deterministic method, and the Markov decision process (MDP), which is a stochastic method, were used to carry out the life-cycle cost analysis. These analyses were applied to data from two state Departments of Transportation. The deterioration curves for steel bridge paint condition rating against age were constructed. Different rehabilitation scenarios were proposed for steel bridge paint. The EA and the MDP were used to analyze and differentiate among the proposed rehabilitation scenarios. The results of the EA were different from those of MDP for the two data sets. MDP favored the “do nothing” scenario until the end of paint life and then a complete repainting. EA indicated that the scenario “do spot repairs at state 3 of the paint life” and repeat that until the end of the bridge life was superior. The results were analyzed to determine the reason for the conflict.

Earthquakes in 1999 and 2000 in Taiwan, Pakistan, and Turkey draw attention to the possibility of an earthquake occurring in a center of population in many diverse locations. In 1992, there was a serious earthquake in Cairo, Egypt, and another in Saudi Arabia. There were fatalities in each of these earthquakes. The most serious and recent earthquake to affect Sydney occurred in December 1989. The center of that earthquake was in Hamilton near Newcastle, 100 kilometers north of Sydney. The office of one of the writers of this paper was destroyed in that earthquake. This paper documents examples of building failures during the 1989 earthquake in Newcastle, Australia. Postdisaster investigative processes are presented, relationships between the insurance companies and building owners are reviewed, and examples are included of repairs after the earthquake. The social and subsequent economic consequences in the decade following the earthquake are discussed. Readers in regions of frequent seismic activities are already familiar with many of the concepts presented in this paper. The value of the paper is the direct observations by the writers, following a rare event in an area not frequented by seismic activities.

This paper presents a seismic evaluation of the San Carlos airport traffic control tower (ATCT) in San Carlos, California, that describes the tower, presents the seismic evaluation of the tower, and defines a rehabilitation approach that upgrades the structure to applicable life-safety standards. The San Carlos ATCT is a Federal Aviation Administration Type L tower, whose primary structure below the control cab (tower shaft) is four inverted L-shaped reinforced concrete members that frame together at the top of the tower shaft. The cab structure is a steel-moment frame. The tower was analyzed with a finite-element model using a response spectrum linear analysis. The goal of this evaluation was to determine if life-safety performance could be demonstrated, and if not, to develop an upgrade approach to achieve this performance. The seismic hazard was based on the maximum considered earthquake defined in the National Earthquake Hazards Reduction Program (NEHRP) recommended provisions. The evaluation shows that the tower cannot achieve life-safety performance due to large deflections in the cab and the formation of a collapse mechanism. The connection base plates for the cab columns (corner window mullions) will form a collapse mechanism at very low seismic motions. Formation of the collapse mechanism is due to base-plate bending failure and subsequent hinging at the base of each column. The recommended rehabilitation approach is to upgrade the columns to reduce deflections to acceptable levels, and also to protect the vulnerable connections. Upgrading the columns consists of welding plates on the interior and exterior column faces and welding deep structural tubing members to the base of each corner column. The writers considered the evaluation of this particular control tower to be of interest to the technical community because of the unique failure mechanism and proposed upgrade approach.