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Infrastructure Failures: Needs for Development of Intelligent DiagnosticsMargery Hines, Ariel Irizarry1, Adnan Jamil, Alexis Paris, and Alyson Stuer2
Prof. Bernal, Prof. Padilla, Prof. Rappaport, Prof. Wadia-Fascetti
AbstractDuring the mid-twentieth century bridge infrastructure expansion occurred at an unprecedented rate withlimited inspection methods until the Point Pleasant, West Virginia bridge failure in 1967. A critical fractureoccurred in a joint of this bridge and, with the normal rush hour loading, the bridge collapsed killing 46. Theimpacts of this failure resulted in the development of inspection practices, and ultimately to a set of nationalstandards for bridge inspection and transportation agencies. Over the half-century following this catastrophemany inspection methods have been used to prevent failures. The most common methods include the use ofdetailed visual inspection and thermal inspection to detect irregularities. Even with these advances,infrastructure failures still occur resulting in social-economical impacts and demonstrating the need forimproved diagnostic methods. Two current failure domains will be presented and confirm the need forinfrastructure health monitoring and the development of an Intelligent Diagnostic system using advancedtechnologies.
Figure 6: This expansion joint had a voidunderneath a thin layer (bottom right). The toplarge void was originally a tiny air void on thesurface.
ReferencesAssessment of Bridge Expansion Joints Using Long-Term Displacement and Temperature Measurement Y. Q. Ni,
X. G. Hua, K. Y. Wong, and J. M. Ko, J. Perf. Constr. Fac. 21, 143 (2007), DOI:10.1061/(ASCE)0887-3828(2007)21:2(143)
Concrete Delamination Caused by Steel Reinforcement Corrosion C. Q. Li, J. J. Zheng, W. Lawanwisut, and R. E. Melchers, J. Mat. in Civ. Engrg. 19, 591 (2007), DOI:10.1061/(ASCE)0899-1561(2007)19:7(591)
Dipayan, Jana (2007). Delamination: A State-of-the-art Review [PowerPoint slides]. Retrieved from Construction Materials Consultants, Inc. Web site: http://www.cmc-concrete.com/CMC%20Seminars/2007%20ICMA%20Delamination.pdf
Finding Delaminations in Concrete Bridge Decks (2003). Retrieved October 6, 2009 , fromThe Acoustical Society of America : http://www.acoustics.org/press/146th/Costley.htm
Gary Strahan (n.d.). Concrete and Asphalt Bridge Deck Delamination. Retrieved October 9, 2009, from Pave Man Pro Web Site:
Himottu, J., Stuer, A. (2009). Analysis of Bridge Connections: A Comparative Study of Bridge and Joint Design. Worcester Polytechnic Institute Major Qualifying Project Report.
Johnson, Marc. (2007). Commision of Inquiry inot the Collapse of a Portion of the de la Concorde Overpass. Retrieved October 12, 2009, from http://www.cevc.gouv.qc.ca/UserFiles/File/Rapport/report_eng.pdf
Nondestructive Testing of the Lawrence Street Bridge Jennifer C. Wood and Kevin L. Rens, ASCE Conf. Proc. 201, 198 (2006), DOI:10.1061/40889(201)198
This work was supported in part by the IGERT: Intelligent Diagnostics for Aging Civil Infrastructure, under theIGERT Program of the National Science Foundation (Award Number DGE-0654176).
Figure 2: An expansion joint with no air voids canbe in tension for extended time with no failure.
Figure 4: A zoomed in view of the expansion jointhad air voids on the surface layer that were easilydetectable.
Figure 5: As the expansion joint was put intotension the voids along the edge of the sampleprovided the location for the sealant to beingpeeling.
Figure 1: This expansion joint with no air voidsperformed well in tests because the lack of voidscreated no point for the sealant to begin peeling.
Figure 3: An expansion joint with air voids in thesurface initially does not indicate air voidsbeneath the surface.
Figure 7: In order to induce air-entrainment in a concrete slab, a hard (machine)-trowel finish is used which provokes delamination.This is a zoomed in view of the core to show the separation of layers created by delamination.
Figure 9: A core from a concrete bridge deck showinga delamination below the surface with no indicationabove.
Figure 8: Delamination due to water bleeding in the finishing of a concrete slab.
Figure 10: Corrosion of reinforcing steel in concrete in thepresence of chloride and atmospheric carbonation. This corrosionoccurs once delaminations contain moisture.
Expansion Joints Sealant VoidsThe first domain is in the expansion joints where a failure can allow moisture to travel to unprotectedsuperstructure members and create problems in the bridge response to temperature changes. The joint failurecan, many times, be attributed to sealant failure, and the sealant fails more often and rapidly when air voids arecreated during the construction and curing. The air voids are currently detected in the sealant during theplacement of the sealant where a uniform pouring is used to reduce the number of air bubbles. Illustrations ofthese failures are shown in Figures 1-6. While these joints are not specifically listed as a cause of catastrophicfailures these failures lead to significant deterioration of the superstructure and substructure member whichcan then cause a catastrophic failure.
Need for Intelligent Diagnostics Today’s bridge inspection methods include tests which are destructive (like coring) and tests which arequalitative and operator judgment dependent (like the chain method). Although reasonably successful, thesetechniques are generally not precise and are subjective, which could mean different conclusions from the samedata dependant on operator. Thus, there is a need for Intelligent Diagnostics that can obtain preciseinformation on these failures in an efficient way.
An example of an intelligent diagnostic system being developed involves thermal imaging. This system iscurrently being tested to find cracks in steel bridge structures under paint. The small amount of friction createdby the crack from molecular movement is conducted to the surface of the paint and then radiated to thesurface. This radiation then travels to the sensor in the thermal camera and is converted to an image we caninterpret. Other methods include using electromagnetic waves to gain a picture of the subsurfacecharacteristics of the deck.
Figure 14: Shows an example of howblood veins in a human arm can beseen as radiation from the warmblood conducts energy to the coolerskin surface. In this same waydelamination and other internalirregularities are located in a concretedeck with thermal imaging. The voidsheat and cool at a different rate thanthe concrete itself showing adifference in temperature during athermal image.
Figure 13: An example of of the typical method forinspection of a bridge deck with a chain bar.Depending on the sound that the chain produceswhile being in contact with the concrete deck, theoperator recognizes possible interior cracks andvoids.
Concrete DelaminationThe second domain is in the concrete deck of the bridge where cracks can develop. These cracks can form dueto environmental conditions or problems with reinforcement, loading, or other stresses. Once a crack hasformed moisture is able to penetrate and contaminate the concrete and corrode rebar. Presently voiddetection in the deck uses a chain drag or hammer to produce echoes used to determine the approximatelocation and size of the void. This practice can be inaccurate due to the fact that data analysis is subjective.There is a need for an alternative, more objective diagnostic to determine the overall health of the structure.Potential intelligent diagnostic alternatives include the use of various wave technologies to develop a combinedsensor that creates a representation of the subsurface.
Figure 11: de la Concorde Overpass collapse which wasdetermined to fail in part to concrete delamination. This failurekilled 5 people.
Figure 12: A detailed view of the concrete delamination thatcontributed to the de la Concorde overpass collapse.
A Case Study: de la Concorde Overpass
This presentation was primarily developed by Ariel Irizarry and Alyson Stuer. This presentation is in additionto a supplemental Intelligent Diagnostic Electrical Engineering Poster.1 Department of Civil Engineering, University of Puerto Rico, Mayagüez2 Department of Civil Engineering, Northeastern University