Bridges In Florida Research Articles

CROSS Safety Alert: Lessons learned from the 2018 Florida bridge collapse during construction

This month we present key elements of a CROSS Safety Alert from December 2020 detailing the failures and lessons learned from the Florida bridge collapse in 2018.

Leveraging Bridge and Environmental Features to Analyze Coating Conditions of Steel Bridges in Florida Using Neural Network Models

Leveraging Bridge and Environmental Features to Analyze Coating Conditions of Steel Bridges in Florida Using Neural Network Models

Identifying Topological Credentials of Physical Infrastructure Components to Enhance Transportation Network Resilience: Case of Florida Bridges

Identifying Topological Credentials of Physical Infrastructure Components to Enhance Transportation Network Resilience: Case of Florida Bridges

Effect of crevice morphology on SRB activity and steel corrosion under marine foulers

Localized corrosion of submerged steel H-piles was detected in a Florida bridge spanning over a brackish river. Analysis of the water showed proliferation of sulfate reducing bacteria (SRB). The steel piles had coincident heavy marine growth that may support biofilms and biocorrosion. The objective of the research described here was to identify the role of the physical morphologies of macrofouling on SRB activity and the aggravation of microbiologically influences corrosion (MIC) of submerged steel bridge. Laboratory experiments were carried out in nutrient-rich environments inoculated with SRB, with both porous and laminate crevice conditions characteristic of soft and hard marine fouling. It was confirmed that SRB proliferation can occur within the crevice environments, but aeration levels under crevices with interaction with the bulk solution can affect SRB activity. Electrochemical impedance spectroscopy provided separation of environmental parameters and surface reaction parameters for the complicated systems relating to corrosion under the porous and laminate crevice geometries.

Influence of Macro- and Microfouling on Corrosion of Steel Bridge Piles Submerged in Natural Waters

AbstractAnomalous localized corrosion of submerged steel H-piles was detected in a Florida bridge. Microbiological analysis at the site indicated a high population of sulfate-reducing bacteria (SRB...

Electrochemical characteristics of antifouling coated steel structure submerged in Florida natural waters to mitigate micro- and macrofouling

Recent findings in a Florida bridge indicated that there are synergistic effects of surface fouling to facilitate biocorrosion. Coatings that have anti-microbial, anti-fouling and barrier-characteristics are applied to steel elements in natural waters to mitigate degradation including corrosion and marine fouling. Electrochemical impedance spectroscopy (EIS) was utilized to identify the performance of a commercially-available anti-fouling coating exposed in three test sites for ~200 days. The results showed that complete prevention of fouling was not attained. EIS showed impedance dispersion associated with surface heterogeneities indicating the coating degradation and biofilm formation as result of reduced coating biocide efficacy.

Application of EIS to Assess Microbiologically Influenced Steel Corrosion in Marine Fouling Crevice Conditions

Microbiologically influenced corrosion (MIC) can cause severe degradation of civil infrastructure. Recently, severe localized corrosion of steel H-piles submerged in a brackish natural water in a Florida bridge was associated with MIC and fouling (Permeh et al., 2017). The localized corrosion cells/pits were of up to 3" in diameter and penetrated through the steel thickness. Microbiological and chemical analysis of the water samples showed a high population of sulfate reducing bacteria (SRB) and a high concentration of sulfate ions amongst other nutrients. The steel piles had noticeable heavy marine growth which were thought to have an effect on the corrosion process by supporting biofilm development, creating localized corrosion and differential aeration cells (Little et al, 2007). In the work described here electrochemical impedance spectroscopy (EIS) was conducted to characterize the development of biofilm in association with fouling crevice environments.Electrochemical impedance spectroscopy (EIS) has been widely used to assess the electrochemical properties of corrosion systems and has been applied to assess physical biofilm conditions for microbiologically influenced corrosion (MIC) (Mansfeld , 2005). EIS measurements over a wide range of frequencies can be used to identify the electrical characteristics associated with the biofilm and the steel substrate. Both laboratory and field exposure tests were conducted. Field exposure tests included long term exposure (~300 days) of steel coupons at a Florida bridge site that sustained macro- and microfouling organisms. Laboratory tests were conducted in nutrient-rich test solutions inoculated with sulfate reducing bacteria (SRB) in either de-aerated or naturally aerated conditions as well as with idealized crevice geometries. EIS testing was made at the OCP condition with 10 mV AC perturbation voltage from frequencies 100 kHz > f >100 mHz.EIS of the specimens inoculated with SRB and with crevices resulted in impedance responses with multiple loops in the Nyquist diagram. Fitting of the impedance response to equivalent circuit analogs were made to identify biofilm, surface layers, and the steel interfacial characteristics during the experimental exposure (Permeh et al.,2019). For non-crevice specimens without SRB inoculations, the impedance response related to the solution resistance, steel interfacial capacitance and charge transfer resistance, characterized by the Randles circuit. However, for the inoculated specimens, impedance dispersion at high frequencies (sometimes showing a loop in the Nyquist diagram) on first approximation was related to the capacitive and resistive characteristics of the biofilm. In crevice environments, a more complicated behavior arose due to uneven current distribution and heterogeneous impedance within the crevice. The impedance behavior for the porous and laminate crevices can be characterized by multiple time constants associated with the crevice outer material, steel interface, and the current distribution effects in the crevice that can be considered by treatments such as a transmission line. In the inoculated non-crevice specimens, the high frequency impedance dispersion was more readily apparent in the Bode phase angle plot. In that representation, the impedance initially showed a uniform valley with a distinct trough between 10 and 100 mHz. With time, two unique troughs developed at frequencies below 1 Hz (Figure 1) for the inoculated specimens. An increase in capacitance was attributed to biofilm growth.In part to provide a quantitative comparison of the overall impedance of the systems (despite the complicating factors for the crevice specimens), on first approach, the total impedance at 100 mHz (|Z100mHz¬|) was compared. The differences in the total impedance for the various test conditions would reflect the resistive and capacitive electrical behavior of the electrolyte, biofilm, and the steel interface that in turn are directly or indirectly related to SRB activity. EIS identified the development of surface films including by an increase in its capacitive behavior that resulted in lower relative total impedance at a given low frequency (i.e. 100 mHz). Test results confirmed that SRB proliferation and corrosion can occur as the fouling macroorganism can accommodate different environmental condition.

Deterioration models for prediction of remaining useful life of timber and concrete bridges: A review

Abstract Bridge deterioration models are used for prioritization and maintenance of bridges. These models can be broadly classified as deterministic and stochastic models. There are mechanistic models (or physical models) as well as Artificial Intelligence (AI)-based models, each of which can be stochastic or deterministic in nature. Even though there are several existing deterioration models, state-based stochastic Markov chain-based model is widely employed in bridge management programs. This paper presents a critical review of different bridge deterioration models highlighting the advantages and limitations of each model. The models are applied to some case studies of timber superstructure and concrete bridge decks. Examples are illustrated for arriving at bridge deterioration models using deterministic, stochastic and Artificial Neural Network (ANN)-based models based on National Bridge Inventory (NBI) data. The first example is based on deterministic model and the second on stochastic model. The deterministic model uses the NBI records for the years 1992–2012, while the stochastic model uses the NBI records for one year (2011–2012). The stochastic model is state-based Markov chain model developed using Transition Probability Matrix (TPM) obtained by Percentage Prediction Method (PPM). The two deterioration models (i.e., deterministic and stochastic models) are applied to timber highway bridge superstructure using NBI condition data for bridges in Florida, Georgia, South Carolina and North Carolina. The illustrated examples show that the deterministic model provides higher accuracy in the predicted condition value than the stochastic Markov chain-based model. If the model is developed based on average of transition probabilities considering the data for the period 1992 to 2012, the prediction accuracy of stochastic model will improve. Proper data filtering of condition records aids in improving the accuracy of the deterministic models. The third example illustrates the ANN-based deterioration model for reinforced concrete bridge decks in Florida based on the NBI condition data for the years 1992–2012. The training set accuracy and testing set accuracy in the ANN model are found to be 91% and 88% respectively. The trained model is utilized to generate missing condition data to fill the gaps due to irregular inspections of concrete bridges. This paper also discusses scope for future research on bridge deterioration modeling.

Surface conditions for microcosm development and proliferation of SRB on steel with cathodic corrosion protection

Steel components used in civil infrastructure are susceptible to microbiologically influenced corrosion (MIC) in marine environments due to the interactions between the metal and its environment with varying water quality parameters (chemical and biological). Sulfate-reducing bacteria (SRB) has been associated with MIC by a cathodic depolarization mechanism due to the reaction of surface hydrogen. Recent findings at a Florida bridge showed severe localized corrosion associated with microbial activity and heavy marine fouling of the submerged steel piles. Cathodic protection can be applied to control the corrosion of steel; however, the mitigation may be impaired by the microbial activity and marine fouling. The objective of this work was to explore reduction reactions on cathodically polarized steel surfaces and evaluate the influence of cathodic polarization on sulfate reduction reaction. It was of interest to characterize the reduction reaction in crevices representative of different physical properties of the marine foulers where SRB can be supported. Field testing was conducted to differentiate the cathodic protection currents that develop in the presence of microorganisms under the layer of marine fouling in natural environments. Laboratory tests were conducted to elucidate the cathodic reactions by potentiostatic cathodic polarization of steel specimens in solutions inoculated with SRB. Field testing showed that proliferation of the bacteria was not inhibited in the presence of cathodic polarization at about −1000 mVCSE and corrosion continued in the localized regions under fouling encrustation. The larger cumulative charge relating to the apparent sulfate reduction by SRB corresponded to higher levels of cathodic polarization. Sulfate reduction by SRB can be a significant contributor to the electrochemical process for steel corrosion with cathodic polarization. For the porous crevice environments, large cathodic currents and high sulfate reduction coincided with the development of sustained SRB growth.

Degradation of coatings for steel in environments susceptible to corrosion associated with fouling

Steel piles in a Florida bridge showed severe localised corrosion uncharacteristic of the general corrosion typically found in marine environments. Sampling from the water and the steel pile surface showed presence of bacteria associated with microbiologically influenced corrosion, MIC. Coincident heavy marine growth was observed. The interactions of marine macro- and microorganisms set up conditions where the severe corrosion occurred. The initiation of macrofouling require initial biofilm presence, but the subsequent fouling crevice environments would sequentially promote enhanced microbe growth (such as sulphate reducing bacteria, SRB) to support MIC. Antifouling and antibacterial coatings that have been developed to manage macrofouling may be applicable to prevent MIC. However, long-term durability of the mitigation coating technology can be compromised. The research objective was to identify the efficacy of biocides in an antifouling coating to mitigate microbial activity that are associated with fouling and MIC. Research included laboratory and field examination of a commercially-available antifouling coating in presence of SRB. It was confirmed that degradation of the coating would result in reduced antibacterial and antifouling efficacy and facilitation of SRB growth and marine fouling.

Cost and environmental analyses of reinforcement alternatives for a concrete bridge

Reinforced Concrete (RC) and Prestressed Concrete (PC) structures using conventional materials in aggressive exposure conditions are susceptible to corrosion. Non-corrosive reinforcement materials such as: Glass Fiber-Reinforced Polymer (GFRP) rebars; Carbon Fiber-Reinforced Polymer (CFRP) strands; Stainless-Steel (SS); and Epoxy-coated steel (ECS) reinforcing bars, are attracting attention as more appropriate options in concrete structures. This paper addresses a Life Cycle Cost (LCC) analysis that verifies the cost performance of four different alternative reinforcement bars for the design of a demonstration FRP-RC/PC bridge in Florida, namely Halls River Bridge (HRB). The four different alternatives to be compared are namely Carbon Steel (CS), SS, FRP, and ECS, and the analysis is performed over 100-years. Additionally, a Life-Cycle Assessment (LCA) is included in the analysis to investigate the environmental credentials of the four design alternatives. Cost sensitivity analyses over specific parameters are included. The parameters analyzed are: reinforcement cost, changes in chloride concentration levels over the bridge service life, and discount rate values. Conclusions and recommendations for standard practices and design of future alternative solutions are then presented.

Characterization of Biofilm Formation and Coating Degradation By Electrochemical Impedance Spectroscopy

Recent findings showed severe localized corrosion of submerged steel bridge piles in a Florida bridge and was associated with microbial activity in presence of marine foulers (Permeh et al, 2017;2018). Microbiologically Influenced Corrosion (MIC) can cause severe degradation of civil infrastructure. MIC has often associated with the formation of biofilm (including the complex interaction of microbe communities and development of extracellular polymeric substances (EPS)) that can influence the corrosion process either by creating oxygen differential aeration cells or generating acidic substances and cathodic reactant depending on the type of bacteria. Sulfate reducing bacteria (SRB) has received much attention in the study of MIC of steel developed in natural waters (Melchers and Wells, 2006; Castaneda and Benetton, 2008). Reactions associated with SRB causes cathodic depolarization of steel leading to the reduction of sulfates to sulfides and promoting steel corrosion (Borenstein,1994). Coatings have been developed to mitigate MIC and marine fouling. Studies have shown that coating blistering and disbondment can occur as a result of microbial attack due to the production of metabolites that degrade coating chemical and physical properties (Mansfield et al.,1998; Muntasser et al.,2002). Recent work evaluated the corrosion mitigation properties of a commercially-available, water-based, self-polishing, antifouling coating in environments that supported SRB as part of a larger research program to identify susceptibility of steel degradation in natural waters due to MIC (Permeh et al.,2019). In the work described here electrochemical impedance spectroscopy (EIS) was conducted to identify microbial activity and degradation of an antifouling coating. EIS was conducted on steel coupons coated with an antifouling coating (with and without coating defects) exposed to SRB inoculated modified Postgate B solution. The exposed coating surface area was ~19.6 cm2 and the coating thickness was ~0.17-0.35 mm. A three-electrode configuration was used for EIS measurements where the coated steel plate was the working electrode, an activated titanium rod was used as a reference electrode, and an activated titanium mesh was used as a counter electrode. EIS measurements were made at OCP condition with 10 mV a.c. perturbation voltage and at frequencies 1Mhz>f>1Hz. The measurements resulted in impedance with multiple loops in the Nyquist diagram (as shown in Figure 1) associated with processes relating to the polymeric coating, development of surface layers (biofilm), and the steel interface. Fitting of the impedance response to equivalent circuit analogs were made to identify coating characteristics and surface layer formation during the experimental exposure in inoculated and non-inoculated solutions. The results revealed near-ideal capacitance for the polymeric coating and a decrease in coating pore resistance. In samples inoculated with SRB, a second high frequency loop developed indicating formation of surface films. The results from EIS indicated degradation of the coating due to its self-polishing characteristics and that formation of surface layers associated with SRB can form as biocide components of the coating become depleted. Continued SRB growth may allow development of marine fouling if the antifouling coating components become less effective and allow possible shelter for SRB to promote MIC. Further work to verify these characteristics in field settings are in progress. References Borenstein, S. (1994). Microbiologically influenced corrosion handbook. Elsevier.Castaneda, H., & Benetton, X. D. (2008). SRB-biofilm influence in active corrosion sites formed at the steel-electrolyte interface when exposed to artificial seawater conditions. Corrosion Science, 50(4), 1169-1183.Mansfield, F., Lee, C. C., Han, L. T., Zhang, G., & Little, B. (1998). The Impact of Microbiologically Influenced Corrosion on Protective Polymer Coatings. University of Southern California Los Angeles Dept of Materials Science And Engineering.Melchers, R. E., & Wells, T. (2006). Models for the anaerobic phases of marine immersion corrosion. Corrosion Science, 48(7), 1791-1811.Muntasser, Z., Al-Darbi, M., Tango, M., & Islam, M. R. (2002, January). Prevention of microbiologically influenced corrosion using coatings. In CORROSION 2002. NACE International. Permeh, S., Boan, M. E., Tansel, B., Lau, K., & Duncan, M. (2019, February). Update on Mitigation of MIC of Steel in a Marine Environment with Coatings. In Coatings+, SSPC 2019. Permeh, S., Li, B., Boan, M. E., Tansel, B., Lau, K., & Duncan, M. (2018, July). Microbially Influenced Steel Corrosion with Crevice Conditions in Natural Water. In CORROSION 2018. NACE International.Permeh, S., Reid, C., Echeverría Boan, M., Lau, K., Tansel, B., Duncan, M., & Lasa, I. (2017, April). Microbiological Influenced Corrosion (MIC) In Florida Marine Environment: A Case Study. In CORROSION 2017. NACE International. Figure 1

Characterization of Biofilm Formation and Coating Degradation by Electrochemical Impedance Spectroscopy

Recent findings showed severe localized corrosion of submerged steel bridge piles in a Florida bridge and was associated with microbial activity in the presence of marine foulers. Microbiologically influenced corrosion (MIC) can cause severe degradation of submerged steel infrastructure with the presence of biofilm associated with microorganisms such as sulfate reducing bacteria (SRB). Coatings have been developed to mitigate MIC and marine fouling. Coating degradation and disbondment can occur as a result of microbial attack due to the production of metabolites that degrade coating chemical and physical properties. In the work described here, electrochemical impedance spectroscopy (EIS) was conducted to identify microbial activity and degradation of an antifouling coating exposed to SRB-inoculated modified Postgate B solution. The measurements resulted in complicated impedance with multiple loops in the Nyquist diagram associated with the coating material, development of surface layers (biofilm), and the steel interface. Deconvolution of the impedance results and fitting to equivalent circuit analogs were made to identify coating characteristics and surface layer formation. EIS test results revealed coating degradation and subsequent formation of surface layers associated with SRB due to coating self-polishing and depletion of biocide components.

Corrosion of Post-Tensioned Tendons with Deficient Grout, Part 3: Segregated Grout with Elevated Sulfate and Vestigial Chloride Content

Severe corrosion of post-tensioned (PT) tendons with pre-packaged thixotropic grout was documented in Florida bridges after less than 8 years of service. In those bridges, corrosion of steel tendon...

Life-Cycle Cost and Life-Cycle Assessment Analysis at the Design Stage of a Fiber-Reinforced Polymer-Reinforced Concrete Bridge in Florida

Abstract To support and promote the deployment of innovative technologies in infrastructure, it is fundamental to quantify their implications in terms of both economic and environmental impacts. Glass Fiber-Reinforced Polymer (GFRP) bars and Carbon Fiber-Reinforced Polymer (CFRP) strands are validated corrosion-resistant solutions for Reinforced Concrete (RC) and Prestressed Concrete (PC) structures. Studies on the performance of Fiber-Reinforced Polymer (FRP) reinforcement in seawater and salt-contaminated concrete have been conducted and show that the technology is a viable solution. Nevertheless, the economic and environmental implications of FRP-RC/PC deployment have not been fully investigated. This article deals with the Life-Cycle Cost (LCC) and Life-Cycle Assessment (LCA) analyses of an FRP-RC/PC bridge in Florida. The bridge is designed to be entirely reinforced with FRP bars and strands and does not include any Carbon Steel (CS) reinforcement. Furthermore, the deployment of seawater concrete in some of the elements of the bridge is considered. LCC and LCA analyses are performed at the design stage. Data regarding equipment, labor rates, consumables, fuel consumption, and disposal were collected during the construction phase, and the analysis was refined accordingly. The FRP-RC/PC bridge design is compared with a traditional CS-RC/PC alternative. Salient differences are discussed to determine the least-impactful solution from both an economic and environmental perspective.

Analysis of girder bridge pier subjected to barge collision considering the superstructure interactions: the case study of a multiple-pier bridge system

This paper aims to numerically evaluate the effects of girder bridge superstructure on the impact responses and load paths transferring the shear force of pier subjected to a moderate-energy barge collision in LS-DYNA. First, two multiple-pier systems of St. George Island Bridge in Florida which have different piers in terms of structural characteristics (such as mass and stiffness), geometry, and the height of impact location are considered as the cases of study. From the numerical barge collision simulations, different impact responses and load transferring paths from the impact location to farther zones are observed. In addition, the sensitivity of impact responses, and the impact load paths transferring shear force to the superstructure mass, stiffness, and damping are studied by developing four different models of pier-superstructure interaction and carrying out a parametric study. It is found that the increase in the value of superstructure parameters has positive effects on the impact forces and the internal stresses in the piers. However, the sensitivity of shear stresses generated at various zones of the pier extremely depends on the impact load paths transferring shear force in different piers with different relative characteristics rather than the superstructure.

Corrosion of Post-Tensioned Tendons with Deficient Grout, Part 2: Segregated Grout with Elevated Sulfate Content

Corrosion failure of post-tensioning (PT) tendons with pre-packaged thixotropic grout has been documented in Florida bridges. Analysis of the deficient grout in Florida PT bridges, where severe corrosion developed, indicated elevated sulfate ion concentration, high pore water pH, low chloride ion content, and enhanced moisture content. Limited information is available on the corrosion behavior of PT strand in grout materials with elevated sulfate ion content. In this work, the corrosion performance of steel strands embedded in deficient grout was evaluated. The deficient grout was cast in large scale test assemblies that would represent geometry and material conditions found in Florida bridges, where PT strand corrosion occurred. Large scale mock up tendons (developed by the modified inclined tube [MIT] test) of about 4.57 m long were cast using expired grout materials, excess of 15% water, and sulfate ion concentrations to create deficiencies and corrosion conditions in the grout environment. Corrosion measurements such as corrosion potential (Ecorr) and corrosion current density (icorr), as well as potentiodynamic polarization tests were performed on the steel probes located along the MIT samples in contact with the deficient grout. Grout characterization parameters included the determination of the grout resistance (Rs), as well as the moisture and sulfate ion content. Also, visual inspection of the MIT samples (steel strand and steel corrosion probes) after a time was performed, as well as the corrosion products characterization. Testing confirmed that enhanced corrosion can occur in the deficient grout with high free sulfate ion accumulation.

Anodic Behavior of Steel in Sulfate-Rich Simulated Grout Pore Solution

Recent observations of severe corrosion of post-tensioned tendons in Florida Bridges were associated with segregated grout containing high sulfate ion concentrations (Lau et al, 2013). Generally, the role of sulfates for steel initiation in alkaline environments have not been well elucidated. In 1970, Gouda identified steel corrosion initiation in saturated calcium hydroxide solutions (pH=12.1) with sulfate concentrations greater than 0.2%; however, steel depassivation was not observed in concrete samples with sodium sulfate concentrations as high as 8%. Dehwah et al. 2002 reported that sulfates did not affect the time to chloride-induced corrosion initiation, but the corrosion rate increased with sulfate content. Research by Carsana and Bertolini in 2011 indicated a strong influence of solution pH on the anodic behavior of steel in sulfate solutions. The objective of the work presented here was to identify the role of early presence of sulfate ions on steel corrosion development. The experiments consisted of anodic polarization tests to determine the anodic behavior of steel samples exposed to alkaine solutions with pH 12.6 or 13.3. Those solutions contained sodium sulfate in the range of 0 to 20,000 ppm. The steel samples were preconditioned for 1 day at either the OCP condition or -1VSCE. The intent to pre-condition the sample at OCP was to initially allow any possible passive film growth to occur. The intent to cathodically pre-condition the steel sample at -1VSCE was to maintain the steel at a low corrosion rate but remaining at active corrosion condition prior to polarization. It this way, it was thought any adverse role of sulfate ions to impede stable passive film formation could be identified. Anodic polarization measurements were made initially from -1 VSCE to +500 mVSCE, with a slow scan rate (0.05 mV/s). Experimental results concluded that anodic polarization tests of steel in pH 13 solution with up to admixed 20,000 ppm sodium sulfate did not indicate strong tendency of sulfates to disrupt passive film formation. However, anodic polarization tests in pH 12.6 and admixed >4,000 ppm sulfate solution indicated instability of passive film resulting in pitting corrosion. It was observed that pH and admixed sulfate concentration will affect the stability of the passive layer. In some cases, as shown in Figure 1, anodic current excursions were indicative of localized depassivation. Indeed, some samples showed indications of pit development. This can be in part explained by the mechanism presented by Gavele (1976) where repassivation of pits can occur in the presence of increased sulfate concentrations within pits but may subsequently diffuse out leading to activation/passivation events. This change of a critical passivation sulfate concentration may result in the observed quick shifts in anodic current. More prominently however, the polarization graphs show transition from passive to active corrosion behavior of steel in solution with the admixed presence of 12,000 to 20,000 ppm sodium sulfate with anodic Tafel slope on the order of ~100 mV/dec. Figure 1

Puente de La Florida. Conexión del barrio de La Florida con la calle Martínez Cachero, Oviedo

La Florida Bridge is a project promoted by Oviedo City Council to connect La Florida and Western Park neighborhoods. The design is an innovation in urban bridges, solving the connection with a flying semi-circle roundabout suspended from its inner edge by a system of cables. Hangers and backstays hang from a loop shaped closed main cable, anchored to a central articulated mast. The structure is completed with a post-tensioned concrete approach viaduct, a composite connection span between roundabout and viaduct, two cantilever footbridges and a concrete counterweight ring.

Modeling Hurricane Hazards and Damage on Florida Bridges

The state of Florida is developing a risk-based decision support model, specifically for its state-maintained bridges, to handle the occurrence of natural hazards, such as hurricanes, tornadoes, floods, landslides, and wildfires. Many bridges in Florida are vulnerable to damage caused by these hazards. With a focus on hurricanes, this paper develops prediction models (estimates of likelihoods) based on historical data of hazard events in Florida, as well as on existing national models. The Poisson process was assumed for the occurrence of natural events; predictions were estimated for the annual probability of occurrence. It was observed that, on average, the probability of hurricane occurrence at bridge locations decreased with the hurricane intensity (category number). In comparison, wildfires, another common hazard, had the highest likelihood estimates of the natural hazards. With a focus on physical damage to bridges, the consequences of hurricanes were also estimated on the basis of historical data within Florida. The damaged bridge components and elements were identified, and the levels of damage and the associated repair costs were assessed.