Upul Attanayake

Rationally Designed Staged Posttensioning to Abate Reflective Cracking on Side-by-Side Box-Beam Bridge Decks

Side-by-side box-beam bridges are often used at sites with tight under-clearance requirements and specified for accelerated construction. However, longitudinal reflective deck cracking is a recurring problem for these bridges and it raises concern for their durability and long-term safety. North American practices of the transverse connection design of this particular bridge are discussed in NCHRP Synthesis 393, and the Michigan design is presented as the preferred procedure. The most recent design in Michigan is an empirical procedure that incorporates the majority of the Synthesis 393 recommended best practices. Yet reflective deck cracking persists. A rational design procedure for which an analysis model was developed is presented here. In the rational design procedure, the analysis model is utilized to calculate the moment demand along the transverse joints. A two-stage transverse posttensioning procedure is recommended following AASHTO load and resistance factor design stipulations based on the moment demand calculated from the analysis model. The second stage of posttensioning precompresses the cast-in-place concrete deck, ensuring crack control. The objective of this study is to demonstrate the effectiveness of the two-stage posttensioning design and implementation procedure to mitigate reflective deck cracking. The effectiveness of the recommended design is demonstrated by utilizing a multistep finite element simulation of the construction process under construction and service loads. The cracking potential of the deck is evaluated under both current Michigan Department of Transportation and the proposed two-stage transverse posttensioning schemes. It is demonstrated that the two-stage posttensioning process can eliminate tensile stresses developed under gravity loading and reduce the temperature load effects to abate reflective deck cracking.

First Full-Depth Deck-Panel Accelerated Bridge Construction Project in Michigan: Constructability Challenges and Lessons Learned

AbstractAccelerated bridge construction (ABC) is gaining momentum as the bridge community is educated on the latest technologies and structural systems that can be implemented under the umbrella of ABC through workshops and demonstration projects. Further, ABC is promoted through various resources provided by the Federal Highway Administration (FHWA) and the Every Day Counts Initiative that recommends implementation of some form of acceleration into every bridge project. The ultimate goal is to make ABC a common practice. Hence, detailed documentation of challenges and lessons learned from previous ABC projects is vital for effective and efficient application of future ABC projects. This paper presents the first full-depth deck-panel ABC project in Michigan with details on the bridge configuration, strengths and limitations of the special provisions, observations during bridge construction, the project team’s timely decisions to overcome some of the constructability challenges, and lessons learned during ...

Bridge Deck Load Testing Using Sensors and Optical Survey Equipment

Bridges are under various loads and environmental impacts that cause them to lose their structural integrity. A significant number of bridges in US are either structurally deficient or functionally obsolete, requiring immediate attention. Nondestructive load testing is an effective approach to measure the structural response of a bridge under various loading conditions and to determine its structural integrity. This paper presents a load-test study that evaluated the response of a prefabricated bridge with full-depth precast deck panels in Michigan. This load-test program integrates optical surveying systems, a sensor network embedded in bridge decks, and surface deflection analysis. Its major contribution lies in the exploration of an embedded sensor network that was installed initially for long-term bridge monitoring in bridge load testing. Among a number of lessons learned, it is concluded that embedded sensor network has a great potential of providing an efficient and accurate approach for obtaining real-time equivalent static stresses under varying loading scenarios.

Capacity Evaluation of a Severely Distressed and Deteriorated 50-Year-Old Box Beam with Limited Data

Safety of adjacent box-beam bridges with distressed and deteriorated beams became a greater concern after the failure of a fascia beam of this bridge type in Pennsylvania, in 2005. As a proactive measure, eight box-beam bridges built in the 1950’s were inspected. Earlier routine inspection reports documented longitudinal cracking at the soffit of a fascia beam of Hawkins Road Bridge. Built in 1957 the bridge carries Hawkins Road over the I-94 freeway in Jackson County, Michigan. In 2006, following a repair decision for replacing the fascia, the beam with the distress was salvaged and the capacity was evaluated through load testing. Remaining prestress calculations showed 77% of the initial prestress that is 3% less than the final prestress used for the design according to the bridge specifications. Concrete modulus of elasticity was evaluated as 5,200ksi and the nominal compressive strength as 8,300 psi. Analysis of load test data indicated that a bridge with such a beam is safe to operate if the transverse connectivity is sufficient for load distribution as envisioned in the design. A major challenge however, is assessing the effectiveness of the load distribution through the transverse connectivity. Further, the importance of identifying concealed corrosion, and quantifying material properties and load distribution is highlighted.

Jointless Bridge Deck with Link Slabs: Design for Durability

Link slabs are used over the piers developing jointless decks while adjacent bridge spans remain simply supported. The Michigan Department of Transportation incorporates link slabs during deck replacements and deep resurfacing. Field performance assessment documented full-depth cracking of most of the link slabs. These cracks allow surface water infiltration, which leads to accelerated deterioration. This study was conducted to address link slab design and performance issues. The literature is inconsistent with the influence of design parameters on link slab performance. The objective was to document the link slab behavior of its design parameters, to propose a method to calculate the link slab moment and axial force, and to propose recommendations for updating current design details and construction procedures. Single-girder, two-span, finite element assemblage models under various types and levels of loads in conjunction with the link slab design parameters were used to evaluate the moments and axial forces developed in the link slab. Analysis showed that support conditions underneath the link slab greatly influence the link slab moment and axial force. Use of moment interaction diagram is recommended for the design. A detailed analysis and design example is presented incorporating live load, temperature gradient load, and the support configurations.

Economic Impact Analysis of Bridge Construction

Traffic disruption from bridge construction has been reduced to several hours through the development of methods characterized as accelerated bridge construction. Associated risks and additional activities involved in the accelerated construction increase initial project cost. This additional cost is offset by the benefits of reduced mobility impact time. Traditionally, the savings in user cost from reduced mobility impact time are used to justify the additional cost of accelerated construction implementations. This paper presents a comprehensive cost model for bridge construction that incorporates the economic impact on surrounding communities and businesses. This economic impact model incorporates user costs, environmental costs, and business revenue changes. The M-100 over the CN Railroad bridge replacement project in Potterville, Michigan, is presented here as a case study to demonstrate the application of economic impact analysis concepts and procedures. This bridge replacement was the third slide-in (i.e., lateral slide) project completed by the Michigan Department of Transportation. Economic impact analysis revealed the benefits of the implementation of the lateral slide bridge construction method at this site.

Monitoring During Lateral Bridge Slide

Slide-in bridge construction (SIBC) is an accelerated bridge construction method. In U.S. state of the art and state of the practice today, the bridge superstructure is moved by sliding laterally into the final alignment following a sequence of construction and demolition events. SIBC implementation components require a temporary support structure, a slide system with railing girders and polytetrafluoroethylene pads or rollers, and an actuating system to initiate and maintain the slide movement. The M-100 bridge over the Canadian National (CN) railway was the third SIBC project implemented by the Michigan Department of Transportation. Each SIBC implementation has been so far unique because the unknowns include slide properties contributing to friction between surfaces, pushing and pulling force levels, and monitoring and controlling the force levels. The purpose of standardization is to develop repeatable procedures for the SIBC method. One aspect of standardization is to develop an understanding of the structural response and the forces developed in the system during slide activities. This understanding requires documentation of various SIBC practices, simulation of slide activities, and monitoring the structural response. The activities of the M-100 road over the CN railway bridge slide, instrumentation and monitoring of the structural response, and the use of acquired acceleration data to calculate the forces that developed during the slide activities are presented.

Economic Impact on Surrounding Businesses due to Bridge Construction

Abstract: The Accelerated Bridge Construction (ABC) has reduced the traffic disruptions during bridge construction. Associated risks and additional activities involved with ABC increase initial project cost. However, ABC brings in the benefits of reduced mobility impact time such as lower maintenance of traffic cost, lifecycle cost, and economic impact on surrounding communities and businesses. Even though, the savings from user cost due to reduced mobility impact time is traditionally used to justify the additional cost for ABC implementation, there are other quantitative factors that need to be considered when selecting a bridge construction method. Economic impact on surrounding businesses is one such factors that need to be considered. This article presents a comprehensive model to quantify economic impact on surrounding businesses. Economic impact analysis considers user cost and business revenue change. M-100 over CN Railroad bridge replacement project in Michigan is used as the case study to illustrate the implementation of economic impact analysis procedure. The case study outcome shows that the economic impact on surrounding businesses by conventional construction (CC) is 16 times greater than the economic impact of ABC.

Monitoring Substructure Movements during Slide-In Bridge Construction

AbstractTo reduce disruption to traffic during bridge replacement, accelerated bridge replacement (ABR) methodologies are being developed. One of the ABR methodologies being implemented is slide-in bridge construction (SIBC), which reduces the total duration of traffic disruption to less than one or two weekends. Because the SIBC activities are new, the system response is unknown. Quantification of the loads acting on permanent and temporary structures during the slide operation is required to develop recommendations for standardizing SIBC. With this purpose, substructure movements were monitored during an SIBC project in Michigan, USA, and the forces acting on the substructure during the slide operation were back-calculated. Theoretically, forces develop in the sliding direction because of friction, and in the vertical direction because of superstructure weight. However, the analysis results indicated that a force couple developed due differential friction at the sliding surfaces, and resulted in rotatin...