Formation of Breakup Ice Jams at Bridges

Bridges can impede the passage of river ice during the breakup event and promote formation of ice jams, with adverse socioeconomic and ecological impacts. Design for ice passage at bridges has largely been empirical and qualitative so that avoidance of ice-jam instigation is often uncertain. It is thus important to develop rational design criteria, based on a thorough understanding of the factors governing the interaction between bridges and ice. This concern is quantified by utilizing recent advances on breakup initiation and comparing driving and resisting forces when the sheet ice cover is about to be set in motion. Retention of ice sheets by in-stream piers can lead to jamming via accumulation of ice rubble that may be arriving from upriver. The resulting methodology is applied to two case studies and yields results that are in full accord with local experience. Though the present findings pertain to the obstruction created by in-stream piers, similar reasoning can be applied to constrictions that may be caused by protruding bridge abutments.     

Evaluation of Cone Penetration Test-Based Settlement Prediction Methods for Shallow Foundations on Cohesionless Soils at Highway Bridge Construction Sites

The cone penetration test (CPT) method is gaining popularity in the United States as one of the premier subsurface exploration techniques. The writers previously monitored settlement behavior of spread footing foundations at five highway bridge construction sites in Ohio and evaluated the standard penetration test-based settlement prediction methods in light of the field performance data. The authors recently conducted CPT sounding at these bridge sites. In this paper, settlement behavior of five spread footings resting on cohesionless soils at two sites were predicted with the CPT-based settlement prediction methods proposed by Amar, DeBeer, Meyerhof, and Schmertmann. The results showed that the prediction methods by Schmertmann and DeBeer were both conservative but reasonably reliable in predicting the settlement of shallow foundations observed in the field.     

Crushing Ice Forces on Structures

On the basis of the results of small-scale and medium-scale indentation tests and full-scale measurements of ice forces, a methodology to estimate crushing ice forces is presented. The main point to note is that the effective pressure depends on the relative indentation speed, which in turn depends on the speed of a moving ice floe and the compliance of a structure. An increase in indentation speed leads to a change in failure mode from ductile to brittle, resulting in decreased effective pressure, and vice versa. The ice forces also depend on the temperature of the ice, because its strength and brittleness increase with decreasing temperature. The two codes for bridge piers and offshore structures are valid for brittle crushing of ice at high indentation speeds, and the recommended design effective pressure from these two codes is the same for wide structures (or large contact area) but differs for narrow structures (or small contact area).     

Best Practices of Bridge System Management—A Synthesis

The paper’s primary purpose is to evaluate current practices in bridge management and inspection procedures in the United States and how State Highway Agencies (SHAs) follow U.S. Department of Transportation guidelines. The efficiency of SHA in utilizing the bridge management systems (BMSs) available to them is analyzed, and the agencies’ readiness to respond to events such as hurricanes, flooding, or earthquakes is evaluated. The paper addresses issues regarding bridges with unknown foundations, interviewing four structural engineers from three SHA regarding these topics. Bridge management officials across the country will benefit from this research by evaluating their agencies’ current practices in comparison with other state agencies. Findings show that state officials attempt to follow very closely the guidelines set by the federal government for bridge inspection and maintenance. However, it was also discovered that, during catastrophic events, agencies rely heavily on managing engineers’ experience and decision-making capabilities because there is no set of response procedures for these extreme conditions. Although powerful BMS tools are available, few SHA utilize these tools to their full capabilities.     

Current Design and Construction Practices of Bridge Pile Foundations with Emphasis on Implementation of LRFD

The Federal Highway Administration (FHWA) mandated the use of the load and resistance factor design (LRFD) approach in the U.S. for all new bridges initiated after September 2007. This paper presents the bridge deep foundation practices established through a nationwide survey of more than 30 DOTs in 2008. Highlighted by this study are the benefits of the LRFD as well as how the flexibility of its usage is being exploited in design practice. The study collected information on current foundation practice, pile analysis and design, pile drivability, pile design verification, and quality control. Since this is the first nationwide study conducted on the LRFD topic following the FHWA mandate, the status on the implementation of LRFD for bridge foundation design was also examined. The study found that: (1) more than 50% of the responded DOTs are using the LRFD for pile design, while 30% are still in transition to the LRFD; and (2) about 30% of the DOTs, who use the LRFD for pile foundations, are using regionally calibrated resistance factors to reduce the foundation costs.     

Centrifuge Modeling of Ship Impact Loads on Bridge Pile Foundations

Bridges that cross navigable waterways may be affected by accidental ship impacts. To better characterize ship impact loads on bridge pier structures, a comprehensive centrifuge model test program involving 48 ship impact tests was performed on a 2×3 pile group and a 3×3 pile group founded in saturated silty sand. These model tests simulated groups of 2-m-diameter by 31.5-m-long pipe piles. The effects of three factors related to the ship (tonnage, speed, and bow structure) and two factors related to the bridge pier structure (superstructure mass and pile-group size) were investigated through these impact tests. The characteristics of the ship impact load were identified and the mechanism of the ship-bridge collision was analyzed. The test results show that the ship impact load was highly dependent on the ship bow structure and the ship impact speed. The test results were compared with other published data and the AASHTO loads. An empirical equation was suggested to relate the ship impact load to the five influencing factors.     

Field-Measured Response of an Integral Abutment Bridge with Short Steel H-Piles

Integral abutment bridges (IABs) with short steel H-pile (HP) supported foundations ( ? 4?m of pile depth) are economical for many environmentally sensitive sites with shallow bedrock. However, such short piles may not develop an assumed, fixed-end support condition at some depth below the pile cap, which is inconsistent with traditional pile design assumptions involving an equivalent length for bending behavior of the pile. In this study, the response of an IAB with short HP-supported foundations and no special pile tip details such as drilling and socketing is investigated. Instrumentation of a single-span IAB with 4-m-long piles at one abutment and 6.2- to 8.7-m-long piles at the second abutment is described. Instrumentation includes pile strain gauging, pile inclinometers, extensometers to measure abutment movement, earth pressure cells, and thermistors. Pile and bridge response during construction, under controlled live load testing, and due to seasonal movements are presented and discussed. Abutment and pile head rotations due to self-weight, live load, and seasonal movements were all found to be significant. Measured abutment movements were likely affected by both temperature changes and deck creep and shrinkage. Based on the field study results presented here, moderately short HPs driven to bedrock without special tip details appear to perform well in IABs and do not experience stresses larger than those seen by longer piles.     

Design and Construction of a Bridge in Very High Performance Fiber-Reinforced Concrete

The design, technology, and construction of a small road bridge made of very high performance fiber-reinforced concrete is described in this paper. The bridge consists of precast prestressed concrete beams with a cast-in-place ordinary concrete deck. A preliminary experimental investigation was conducted to define the mix design, to establish the properties of the material and its durability, and to study the flexural behavior of the prestressed concrete beams with and without the concrete deck. The effect of steel fibers at the structural level, where there is an influence of constitutive behavior and size effects, was analyzed by testing a prestressed beam using very high performance fiber-reinforced concrete without fibers. The establishment of the structural properties of the material then allowed the design of the final section of the bridge beams and the definition of a model to justify the design rules adopted. This project represents an attempt to demonstrate the industrial feasibility of very high performance concrete structural elements manufactured with conventional raw materials and usual production techniques and to evaluate the production technology when utilizing steel fibers.     

Replacement of Pontesei Bridge, Italy

Pontesei Dam is a major concrete dam built after World War II across the canyon of Maè Creek (Valle di Zoldo) in the Italian Eastern Alps. Just upstream from the dam, a gully discharges water from steep mountains. The only road serving the dam and the entire valley upstream of the dam runs along the mountainside and crosses the gully. In 1959, an exceptionally rainy season caused a flood, which destroyed the bridge. A temporary Bailey bridge was subsequently built by the army, but in 1990 it was decided to design a new bridge. The main challenges posed to the designer included building the new deck and the abutments underneath the Bailey bridge without disrupting traffic, hoisting the deck just to the bottom of the Bailey bridge, and finally substituting the new deck for the Bailey bridge in one day. Other problems included the instability of the rock mass at the abutments and the gravitative convergence of the two sides of the gully. This paper describes the design, construction, and testing of the bridge replacement and the bridge abutments.     

Integral Abutment Bridge Behavior: Parametric Analysis of a Massachusetts Bridge

Integral abutment bridges are often a preferred bridge type for moderate spans throughout the United States. However, design methods and construction details vary from state to state. Variations between states are noted in the methods employed to accommodate deformations in the piles. The significance of these differences was evaluated through a finite-element study. The effects of backfill properties and soil restraint on piles were evaluated with regard to bridge distortions and maximum moment realized in the piles. Results show that bridge expansion is predominantly affected by backfill conditions, whereas contraction is influenced by pile restraint conditions. Pile moments are minimized when denser backfill and lower pile restraint are provided. The influence of abutment soil-structure spring modeling assumptions is addressed. Models were calibrated to the reference bridge at Orange-Wendell, Mass, which has been instrumented and data collected for 4 years.     

Modeling Ice Passage at Navigation Locks

Physical and numerical models were used to assess ice passage at navigation locks, focusing on key factors such as the design of the lock filling and emptying system and the intakes to the lock filling culverts. Unconventional ice passage techniques such as manifolds in the miter gates were also evaluated. Physical model results were compared to field observations and to a parallel series of tests using the DynaRICE ice-hydraulic numerical model. The study focused on three general ice processes at locks: (1) ice accumulating near culvert intakes during lock filling; (2) drawing ice into the lock chamber; and (3) flushing ice out of the lock. Ice accumulation thickness in the upper lock approach was found to be the most important parameter affecting ice passage into the lock chamber. Physical and numerical model results compared reasonably well, proving DynaRICE to be a useful tool for assessing ice passage for new lock designs.     

Roca Spur Bridge: The Implementation of an Innovative Deicing Technology

The heated deck of Roca Spur Bridge is the first implementation in the world using conductive concrete for deicing. Conductive concrete is a concrete mix containing a certain amount of electrically conductive components in a regular concrete matrix, designed to enable conduction of electricity. Due to its electrical resistance, conductive concrete can generate enough heat to prevent ice formation on a paved surface when connected to a power source.     

Chloride Ion Transport in Bridge Deck Concrete under Different Curing Durations

During freezing temperatures, ice accumulates on exposed concrete slabs such as bridge decks. Deicing salts such as calcium chloride are applied to control this ice formation. These salts migrate down to the reinforcing steel, and they can break down the passivation layer on steel, causing it to corrode. This paper is part of a broader research study to explore the possibility of opening the bridge decks earlier than the 10–12 days as practiced now, by decreasing the number of wet-mat curing days. Seven concrete mixtures typically used in Texas bridge decks were evaluated for chloride permeability using the ponding test (AASHTO T259). The primary experimental variables were the curing duration, type and percentage of supplemental cementitious materials, type of coarse aggregate, duration of ponding, and the surface preparation of ponded concrete specimens. Results of the investigation indicated that curing duration may be decreased for some concrete mixtures as no apparent improvement was shown after a specific curing duration, which ranged from 2 to 8 days depending on the mix.     

Enlarged Base (Belled) Piles for Use in Ice or Ice-Rich Permafrost

The influence of enlarging the base of a pile on the total and end bearing capacities of a pile in ice-rich permafrost is evaluated along with the principles used to evaluate the total capacity of uniform diameter and belled piles of the same length in ice-rich soils. Procedures developed by Weaver and Morgenstern in 1981 for predicting the total capacity of straight piles are extended to predict the capacity of belled piles to study the capacity of enlarging the pile base. The total capacity can be substantially improved through the use of belled piles. Techniques to form the bell in different types of permafrost are reviewed with an emphasis on jet cutting. The techniques to allow for installation are described as well as the need for field tests to confirm the proposed installation technique and the predicted increased capacity.     

Estimating Equilibrium Scour Depth at Cylindrical Piers in Experimental Studies

Using data from six very long experiments on local scour at single cylindrical piers, some of the existing equilibrium criteria found in the literature are assessed. It is found that common criteria, which consider scour depth increments in 24?h or the observation of horizontal plateaux in records of scour depth time evolution, can incur important errors on the equilibrium scour depth. Using some of the expressions for time evolution found in the literature to fit the experimental data and infer equilibrium scour depth through extrapolation to infinite time, it is found that the equilibrium scour depth cannot be specified, in general, for experiments shorter than one to two weeks.     

Lessons Learned from an Emergency Bridge Replacement Project

The terrorist attack on September 11, 2001, and subsequent potential threats to U.S. transportation systems have presented an urgent need to develop emergency response plans to quickly react to the possible consequences of extreme events. Extreme events include terrorist attack as well as man-made and natural disasters such as explosions, fires, floods, and earthquakes. The objective of this research was to identify strategies and technologies to quickly restore the use of highway bridges, a critical component of the nation’s transportation network, in case they are damaged or destroyed by extreme events. One of the tasks associated with this research was to conduct case studies of previous bridge replacements following extreme events. By studying these cases, the research team sought to identify and expand on lessons learned, address which actions did and did not work well given the circumstances of the incident, and incorporate lessons into the emergency response plan for highway bridges. This paper presents the findings from one of the case studies, the I-40 Webbers Falls Bridge in Oklahoma.     

Improved Longitudinal Joint Details in Decked Bulb Tees for Accelerated Bridge Construction: Concept Development

This paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck that is cast and prestressed with the girder provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is a perceived problem with durability of longitudinal joints used to connect adjacent girders. This paper presents the results of a study to assess potential alternate joint details based on constructability, followed by testing of selected details. Seven reinforced concrete beam specimens connected with either lapped headed reinforcement or lapped welded wire reinforcement were tested along with a specimen reinforced by continuous bars for comparison. Test results were evaluated based on flexural capacity, curvature at failure, cracking, deflection, and steel strain. Based on the survey and the experimental program, a headed bar detail with a 152 mm (6 in.) lap length was recommended for replacing the current welded steel connector detail.     

Ice Tank Tests on Ice Rubble Loads Against a Cable-Moored Conical Platform

Presented herein are ice-tank data concerning ice-rubble loads against a moored conical platform. Of prime interest is how rubble-ice loads are influenced by horizontal stiffness of the platform’s mooring system. An important, and heretofore undocumented, feature of rubble loading and clearing around the platform is the accumulation of ice rubble as a false bow, or prow, at the platform’s leading perimeter. The ice-tank data show that, under certain conditions of ice-rubble loading, the lowest stiffness of mooring tested resulted in prow instability and sloughing, which in turn lead to a cyclic pattern of loading, and to rubble congestion around the platform. An outcome of such rubble congestion was a marked increase in the overall rubble-ice load exerted against the platform.     

Underwater Fiber–Reinforced Polymers Repair of Prestressed Piles in the Allen Creek Bridge

This paper presents an overview of a demonstration project in which corroding prestressed piles located in tidal waters were wrapped underwater using carbon and glass fiber-reinforced polymer material. An innovative instrumentation scheme was developed to allow assessment of the prewrap and postwrap corrosion state using linear polarization. This system is simple to install and eliminates the need for wiring or junction boxes. The underwater wrap used a unique water-activated urethane resin system that eliminated the need for cofferdam construction. Linear polarization measurements taken before and after wrapping indicate that the corrosion rate in the wrapped specimens is consistently lower than those in its unwrapped counterpart. These preliminary findings are encouraging and suggest that underwater wrapping without cofferdam construction may provide a cost-effective solution for pile repair.     

Probability of Drift Blockage at Bridge Decks

Drift seriously increases the destructive power of a flood event. Drift accumulations and blockages at river bridges are a widespread problem, possibly leading to their total destruction. Although drift is a major threat, limited knowledge is currently available on the likelihood of drift blocking. Drift either accumulates at a single pier, or it spans between two or more piers, or it gets blocked at the bridge deck. The main purpose of this experimental study is to analyze the drift-blocking probability at bridge decks depending on: (1)?drift dimensions, (2)?freeboard, (3)?flow characteristics, and (4)?bridge characteristics. Systematic model tests include the accumulation of both single logs and rootstocks. The test flow conditions represent a major flood event, where the freeboard tends to zero and the drift is able to touch the bridge deck. The results indicate significant effects of the freeboard, the approach flow Froude number, and the bridge characteristics on drift accumulation. They allow for an estimation of the blocking probability and therefore can be used as a risk assessment tool to identify endangered bridges prior to a flood event. The model tests demonstrate further the randomness of the blocking process, resulting occasionally in a wide scatter of data.