Resources

Alta Vista values candid communication and transparency. To that end, we encourage our team members to document and share best practices and expert knowledge openly. Explore the resources below at your leisure and, if you can't find what you are looking for, please contact us—we welcome the opportunity to begin a conversation.

Alta Vista's Publications

A Forensic Study of the Collision of a Cargo Ship with the Vincent Thomas Bridge, 2007 A. Mazen Wahbeh et al.

Abstract:

On 27 August, 2006, the Vincent Thomas Bridge, a critical 1850-m suspension bridge, located in the metropolitan Lost Angeles region had a collision with a large cargo ship, passing under the bridge. This incident left the transportation authorities wondering about the structural integrity of the bridge. Immediately after the accident, the bridge was closed to traffic until structural engineers from the California Department of Transportation (Caltrans) completed an analysis of the bridge.

Interest in the field of structural health monitoring (SHM) has been growing at a fast pace in the recent past due to the great developments in the fabrication of innovative sensors, the ease of deploying sensor networks, and the associated high growth in the computational power that is becoming readily available with personal computers. Furthermore, the development of sophisticated digital signal processing tools for the analysis of vibration signatures of dispersed civil infrastructure system has generated a lot of interest in the application of such analysis tools, in conjunction with real-time monitoring approaches, in order to perform virtually continuous condition assessment of any instrumented structure.

A real-time continuos monitoring system has been developed by the researchers at the University of Southern California, and deployed onto the Vincent Thomas Bridge since 2005. Using the monitoring system, the dynamic response of the bridge was successfully recorded before and after the incident as well as during the collision process. The analysis of these valuable data allows the transportation authorities to quantify the effects of the collision on the bridge structural condition, which would otherwise be infeasible with traditional visual bridge inspection approaches.

A forensic study was performed to assess the structural condition of the bridge before and after the incident. Relatively long time history records of the bridge oscillations were used to analyze its nearly stationary response by applying multi-sensor system identification approaches, utilizing the NExT-ERA methods. Both global and local identification methods were applied to detect significant changes in the bridge vibration signature. The identification results shown that there are no significant system changes due to the collision.

By utilizing web-based SHM system that is installed on the bridge, it is demonstrated that analysis of the acquired sensor measurements can provide the owners of critical infrastructure system with a forensic tool that enables reliable and rapid assessment to analyze the circumstances and consequences of extreme events to which the target system is subjected.

– Yun, H-B., Nayeri, R.D., Masri, S.F., Wahbeh, M., Tasbihgoo, F., Caffrey, J.P., and Sheng, L-H., (2007), “A Forensic Study of the Collision of a Cargo Ship with the Vincent Thomas Bridge,” Proc. of World Forum on Smart Materials and Smart Structures Technology 2007, 22-27 May 2007, Chongqing and Nanjinng, China.

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A Practical Guide to Welding Closed Ribs (U-Ribs), 2013 Patrick Lowry et al.

Abstract:

Closed ribs serve as the primary stiffening elements for orthotropic box girders, which when constructed in series, comprise the orthotropic steel bridge deck. Two partial joint penetration (PJP) groove welds connect each of the closed ribs to the bridge deck plates. Due to long-term fatigue cracking that can occur with poor weld quality, consistent quality in the PJP closed rib weld is essential to the structure’s ability to meet the specified design life.

The fabrication of several bridges employing the orthotropic steel deck design illustrated the challenges fabricators and contractors face when performing closed rib welding (also referred to as U-rib welding). Bridges examined in this paper include the new Tacoma Narrows Bridge in Tacoma, Washington, the Alfred Zampa Memorial (new Carquinez) Bridge in Crockett, California, the Bronx-Whitestone Bridge in New York City, New York, and the new eastern span of the San Francisco-Oakland Bay Bridge in Oakland, California.

The PJP groove weld is a non-standard joint and can create numerous challenges for fabricators. Issues that have arisen through the fabrication of closed rib welds on various orthotropic steel bridge projects are cracked tack welds, solidification cracking, and consistent maintenance of the specified weld penetration level.

This paper will discuss the practical steps fabricators and contractors can take to successfully perform closed rib welding, which include developing a careful welding procedure to control weld parameters, performing multi-pass welding, standardizing tack weld length and size, and performing NDT to identify areas requiring repair.

– Patrick Lowry, Keith Hoffman, and Aaron Prchlik. “A Practical Guide to Welding Closed Ribs (U-Ribs)”, Seventh National Seismic Conference on Bridges & Highways, Oakland, CA, May 2013.

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A Programmable Wireless Sensing System for Structural Monitoring, 2006 A. Mazen Wahbeh et al.

Abstract:

Recent work has examined the design of wireless sensor network (WSN) systems for structural health monitoring (SHM). Wireless sensors enable dense monitoring of large physical structures and promise enormous ease and flexibility of deployment of instrumentation, as well as low maintenance and deployment costs. However, programming sensing applications on a network of wireless sensors remains a difficult and time-consuming endeavor. This is due in part to the complexity of such systems. Their limited battery resources, and the highly variable performance of wireless communication in different environments represent significant constraints that, if each application developer were forced to deal with, can significantly increase the time to develop robust applications. We have been developing a networked software system called TENET that simplifies the programming of wireless sensor actuator systems. A TENET system is a two-tier networked system consisting of two classes of nodes: a higher-tier with several nodes containing 32-bit processors and IEEE 802.11b radios, and a lower-tier comprising battery-operated sensor nodes with less-capable processors, low-power radios. Our TENET software runs application code on the higher-tier nodes, and provides a generic interface for tasking sensors and actuators. This separation of functionality simplifies application development greatly, since developers can reuse networking and sensor data extraction code, thereby reducing application development time. We will report on the development of and experiences with structural data acquisition application for a long-span suspension bridge using TENET. We will report on our experiences in deploying a two-tier network of wireless sensors on the bridge. We will report on the performance of the TENET system in this setting as well.

– Jeongyeup Paek, Omprakash Gnawali, Ki-Young Jang, Daniel Nishimura Ramesh Govindan, John Caffrey, Mazen Wahbeh, and Sami Masri, (2006), “A Programmable Wireless Sensing System for Structural Monitoring”, Fourth World Conference on Structural Control and Monitoring (4WCSCM), July 2006.

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A Study of Time-Domain Techniques for Modal Parameter Identification of a Long Suspension Bridge with Dense Sensor Arrays, 2009 A. Mazen Wahbeh et al.

Abstract:

While numerous studies have been published concerning the application of a variety of system identification techniques in conjunction with vibration measurements from civil infrastructure systems, there is a paucity of publications addressing the influence of algorithm-specific control parameters that impact the correct and efficient application of the selected identification scheme. Furthermore, as dense sensor arrays become widely accessible in civil infrastructure applications, voluminous amounts of multichannel data streams are becoming available for processing, thus imposing new demands on identification procedures regarding high-dimensionality (in both the spatial as well as the temporal domains) requirements that may render some methods inapplicable if careful attention is not paid to practical implementation issues. This paper provides a comprehensive study of three time-domain identification algorithms applied in conjunction with the Natural Excitation Technique in order to extract the modal parameters of a newly constructed long-span bridge that was monitored, in its virgin state, over a relatively long period of time with a state-of-the-art dense sensor array. The three methods used are: the eigensystem realization algorithm (ERA), the ERA with data correlations, and the least squares algorithm. One of the critical issues in the mentioned algorithms is selection of the reference degree-of-freedom (DOF). Previous experiences have shown that one cannot rely on a single reference DOF for identification of all modes. Consequently, the aforementioned identification formulations were modified to include multiple reference DOF, simultaneously, or one at a time. An autonomous algorithm was presented to distinguish the genuine structural modes from spurious noise or computational modes. Based on some parameter studies, some useful guidelines for the selection of critical user-selectable parameters are presented.

– Nayeri, R., Tasbihgoo, F., Wahbeh, M., Caffrey, J., Masri, S.F., Conte, J.P., and Elgamal, A., (2009), “A Study of Time-Domain Techniques for Modal Parameter Identification of a Long Suspension Bridge with Dense Sensor Arrays” ASCE Journal of Engineering Mechanics, (July 2009), pp 669-683.

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A Vision-Based Approach for the Direct Measurement of Displacements in Vibrating Systems, 2003 A. Mazen Wahbeh et al.

– Wahbeh, A.M., and Caffrey, J.P, and Masri, S.F., (2003), “A Vision-Based Approach for the Direct Measurement of Displacements in Vibrating Systems,” Journal of Smart Materials and Structures, vol 12, pp 785-794.

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Alternative Building Material with Modified Composition, 2002 Jinesh Mehta

– Jinesh Mehta, “Alternative Building Material with Modified Composition”, A national technical paper presentation contest, Government College of Engineering Pune, India, February 2002.

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Analytical and Experimental Studies in Nonlinear Structural Health Monitoring and System Identification, 2003 A. Mazen Wahbeh

– Wahbeh, A. M., 2003. “Analytical and Experimental Studies in Nonlinear Structural Health Monitoring and System Identification”, University of Southern California, Los Angeles, CA.

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Application of a Web-Enabled Real-Time Structural Health Monitoring System for Civil Infrastructure Systems, 2004 A. Mazen Wahbeh et al.

Abstract:

The system architecture of a novel structural health monitoring system that is optimized for the continuous real-time monitoring of dispersed civil infrastructures is presented. The monitoring system is based on a highly efficient multithreaded software design that allows the system to acquire data from a large number of channels, monitor and condition this data, and distribute it, in real time, over the Internet to multiple remote locations. Bandwidth and latency issues that impact the operation of monitoring systems are discussed. The application of the monitoring system under discussion to a long span, flexible bridge in the metropolitan Los Angeles region is described. The bridge had previously been instrumented with 26 strong motion accelerometers. Sample ‘quick analysis’ results continuously provided by the monitoring system are presented and interpreted. System identification results, obtained through off-line batch processing, are presented for a data set from a recent earthquake that automatically triggered the recording capability of the system. It is shown that, using a time domain system identification approach, the bridge stiffness and damping matrices can be identified from the earthquake data set and subsequently used to determine the bridge modal properties, such as frequencies and damping ratios. In this approach the bridge is modeled as a multi-input/multi-output system with order compatible with the number of available sensors. Implementation issues requiring further investigation are presented and discussed.

– Masri, S.F., Sheng, L-H, Caffrey, J.P., Nigbor, R.L., Wahbeh, M. and Abdel-Ghaffar, A.M., (2004), “Application of a Web-Enabled Real-Time Structural Health Monitoring System for Civil Infrastructure Systems,” Journal of Smart Materials and Structures, Vol 13, pp 1269-1283.

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Challenges In Fabrication Of Precast Prestressed Concrete Super Girders, 2013 Mohammad Fatemi et al.

Abstract:

Construction is underway on a California Department of Transportation (Caltrans) widening project on SR 99 in Nicolaus, CA. A major element of this project is Precast/Prestressed bulb tee super girders with a maximum height of 8’6”, up to 120’ long and weighing up to 90 tons each for a bridge over the Feather River. Fabrication of these tall and slender girders posed unique challenges such as arrangement of post tensioning ducts in a thin web, high performance concrete with compressive strength of 8,500 psi, transportation and handling issues. As the owner, California Department of Transportation enforced a rigorous Quality Assurance scheme to ensure fabrication met its challenges. This process included submission of a detailed Quality Control Plan by the fabricator. Caltrans material engineers and inspectors were involved from the onset of fabrication and worked closely with the fabricator for a quality product. This paper details the unique difficulties and challenges encountered during the course of the fabrication and how Caltrans’ and the fabricator’s combined proactive approach resulted in a successful delivery of the product.

– Mohammad J. Fatemi, PhD, PE, Robert Kim, PE, and Mike Hein, PE, “Challenges In Fabrication Of Precast Prestressed Concrete Super Girders”, PCI Convention and National Bridge Conference, Grapevine, TX, September 2013.

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Computational Validation of a Forced-Vibration Method for Structural Health Monitoring of Large-Scale Structures, 2006 A. Mazen Wahbeh et al.

– Wahbeh, A.M., Caffrey, J.P, and Masri, S.F., (2006), “Computational Validation of a Forced-Vibration Method for Structural Health Monitoring of Large-Scale Structures,” Proc Third European Workshop on Structural Health Monitoring (3EWSHM), 5-7 July 2006, Granada, Spain.

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Constructability Challenges of East Tie-In Fabrication for SFOBB, 2013 Jinesh Mehta et al.

– B. Casey, K. Hoffman, J. Mehta, and K. Terpstra, “Constructability Challenges of East Tie-In Fabrication for SFOBB”, Seventh National Seismic Conference on Bridges and Highways, Oakland, CA, May 2013.

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Design and Application of a Web-Enabled Real-Time Structural Health Monitoring System for Civil Infrastructures, 2006 A. Mazen Wahbeh et al.

Abstract:

The system architecture of a novel structural health monitoring system that is optimized for the continuous real-time monitoring of dispersed civil infrastructures is presented. The monitoring system is based on a highly efficient multithreaded software design that allows the system to acquire data from a large number of channels, monitor and condition this data, and distribute it, in real time, over the Internet to multiple remote locations. Bandwidth and latency issues that impact the operation of monitoring systems are discussed. The application of the monitoring system under discussion to a long span, flexible bridge in the metropolitan Los Angeles region is described. The bridge had previously been instrumented with 26 strong motion accelerometers. Sample ‘quick analysis’ results continuously provided by the monitoring system are presented and interpreted. System identification results, obtained through off-line batch processing, are presented for a data set from a recent earthquake that automatically triggered the recording capability of the system. It is shown that, using a time domain system identification approach, the bridge stiffness and damping matrices can be identified from the earthquake data set and subsequently used to determine the bridge modal properties, such as frequencies and damping ratios. In this approach the bridge is modeled as a multi-input/multi-output system with order compatible with the number of available sensors. Implementation issues requiring further investigation are presented and discussed.

– Masri, S.F., Wahbeh, M., Caffrey, J., Nigbor, R., Abdel-Ghaffar,A., and Sheng, L., (2006), “Design and Application of a Web-Enabled Real-Time Structural Health Monitoring System for Civil Infrastructures,” Proc Civil Engineering Infrastructure Systems (CEIS 2006), 12-14 June 2006, American University of Beirut, Lebanon, p 48.

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Design and Implementation of a Web-Enabled Real-Time Monitoring System for Civil Infrastructures, 2004 A. Mazen Wahbeh et al.

Abstract:

The system architecture of a novel structural health monitoring system that is optimized for the continuous real-time monitoring of dispersed civil infrastructures is presented. The monitoring system is based on a highly efficient multithreaded software design that allows the system to acquire data from a large number of channels, monitor and condition this data, and distribute it, in real time, over the Internet to multiple remote locations. Bandwidth and latency issues that impact the operation of monitoring systems are discussed. The application of the monitoring system under discussion to a long span, flexible bridge in the metropolitan Los Angeles region is described. The bridge had previously been instrumented with 26 strong motion accelerometers. Sample ‘quick analysis’ results continuously provided by the monitoring system are presented and interpreted. System identification results, obtained through off-line batch processing, are presented for a data set from a recent earthquake that automatically triggered the recording capability of the system. It is shown that, using a time domain system identification approach, the bridge stiffness and damping matrices can be identified from the earthquake data set and subsequently used to determine the bridge modal properties, such as frequencies and damping ratios. In this approach the bridge is modeled as a multi-input/multi-output system with order compatible with the number of available sensors. Implementation issues requiring further investigation are presented and discussed.

– Masri, S.F., Sheng, L-H, Wahbeh, M., Caffrey, J.P., Nigbor, R.L., and Abdel-Ghaffar, A.M., (2004), “Design and Implementation of a Web-Enabled Real-Time Monitoring System for Civil Infrastructures,” Proc Second International Conference on Bridge Maintenance, Safety and Management, IABMAS’04, Kyoto, Japan, 18-22 October 2004, Paper 222.

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Development of an Economic Dust Palliative for Limestone Surfaced Secondary Roads, Part 1, 1989 A. Mazen Wahbeh et al.

Abstract:

This research project was directed at laboratory and field evaluation of sodium montmorillonite clay (bentonite) as a dust palliative for limestone surfaced secondary roads. It had been postulated that the electrically charged surfaces of the clay particles could interact with the charged surfaces of the limestone and act as a bonding agent to agglomerate fine (-#200) particulates and also to bond the fine particulates to larger (+#200) limestone particles.

Laboratory testing using soda ash dispersed bentonite treatment of limestone fines indicated significant improvement of compressive strength and slaking characteristics. It was recommended that the project proceed to field trials and test roads were constructed in Dallas and Adair counties in Iowa.

Soda ash dispersed bentonite solutions can be field mixed and applied with conventional spray distribution equipment. A maximum of 1.5 percent bentonite (by weight of aggregate) can be applied at one time. Higher applications would have to be staged allowing the excess moisture to evaporate between applications. Construction of higher application treatments can be accomplished by adding dry bentonite to the surfacing material and then by dry road mixing. The soda ash water solution can then be spray applied and the treated surfacing material wet mixed by motor graders to a consistency of 3 to 4 inch slump concrete. Two motor graders working in tandem can provide rapid mixing for both methods of construction.

Calcium and magnesium chloride treatments are 2 to 3 times more effective in dust reduction in the short term (3-4 months) but are prone to washboarding and potholing due to maintenance restrictions. Bentonite treatment at the 2 to 3 percent level is estimated to provide a 30 to 40 percent dust reduction of the long term (18-24 months). Normal maintenance blading operations can be used on bentonite treated areas. Vehicle braking characteristics are not adversely affected up to the 3.0 percent treatment level.

The bentonite appears to be functioning as a bonding agent to bind small particulates to larger particles and is acting to agglomerate fine particles of limestone. This bonding capability appears recoverable from environmental effects of winter, and from alternating wet and dry periods. The bentonite appears to be able to interact with new applications of limestone maintenance material and maintains a dust reduction capability.

Soda ash dispersed bentonite treatment is approximately 10 times more cost effective per percent dust reduction than conventional chloride treatments with respect to time. However, the disadvantage is that there is not the initial dramatic reduction in dust generation as with the chloride treatment. Although dust is reduced 30 to 40 percent after treatment there is still dust being generated and the traveling public or residents may not perceive the reduction.

– A. M. Wahbeh, K. L. Bergeson, May, 1989. “Development of an Economic Dust Palliative for Limestone Surfaced Secondary Roads, Part 1,” Engineering Research Institute, Iowa State University, Ames, Iowa.

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Development of an Economic Dust Palliative for Limestone Surfaced Secondary Roads, Part 2, 1989 A. Mazen Wahbeh

Abstract:

This research project was directed at laboratory and field evaluation of sodium montmorillonite clay (bentonite) as a dust palliative for limestone surfaced secondary roads. It had been postulated that the electrically charged surfaces of the clay particles could interact with the charged surfaces of the limestone and act as a bonding agent to agglomerate fine (-#200) particulates and also to band the fine particulates to larger (+#200) limestone particles.

Laboratory testing using soda ash dispersed bentonite treatment of limestone fines indicated significant improvement of compressive strength and slaking characteristics. It was recommended that the project proceed to field trials and test roads were constructed in Dallas and Adair counties in Iowa.

Soda ash dispersed bentonite solutions can be field mixed and applied with conventional spray distribution equipment. A maximum of 1.5 percent bentonite (by weight of aggregate) can be applied at one time. Higher applications must have to be staged allowing the excess moisture to evaporate between applications. Construction of higher application treatments can be accomplished by adding dry bentonite to the surfacing material and then by dry road mixing. The soda ash water solution can then be spray applied and the treated surf acing material wet mixed by motor graders to a consistency of 3 to 4 inch slump concrete. Two motor graders working in tandem can provide rapid mixing for both methods of construction.

Calcium and magnesium chloride treatments are 2 to 3 times more effective in dust reduction in the short term (3-4 months) but are prone to washboarding and potholing due to maintenance restrictions. Bentonite treatment at the 2 to 3 percent level is estimated to provide a 30 to 40 percent dust reduction over the long term (18-24 months). Normal maintenance blading operations can be used on bentonite treated areas. Vehicle braking characteristics are not adversely affected up to the 3.0 percent treatment level.

The bentonite appears to be functioning as a banding agent to bind small particulates to larger particles and is acting to agglomerate fine particles of limestone. This bonding capability appears recoverable from environmental effects of winter, and from alternating wet and dry periods. The bentonite appears to be able to interact with new applications of limestone maintenance material and maintains a dust reduction capability.

Soda ash dispersed bentonite treatment is approximately 10 times more cost effective per percent dust reduction than conventional chloride treatments with respect to time. However, the disadvantage is that there is not the initial dramatic reduction in dust generation as with the chloride treatment. Although dust is reduced 30 to 40 percent after treatment there is still dust being generated and the traveling public or residents may not perceive the reduction.

– A. M. Wahbeh, K. L. Bergeson, December, 1989. “Development of an Economic Dust Palliative for Limestone Surfaced Secondary Roads, Part 2,” Engineering Research Institute, Iowa State University, Ames, Iowa.

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Direct Measurement of Displacement in Vibrating Structures Through Vision-Based Approaches, 2003 A. Mazen Wahbeh et al.

Abstract:

This paper reports the results of an analytical and experimental study to develop, calibrate, implement and evaluate the feasibility of a novel vision-based approach for obtaining direct measurements of the absolute displacement time history at selectable locations of dispersed civil infrastructure systems such as long-span bridges. The measurements were obtained using a highly accurate camera in conjunction with a laser tracking reference. Calibration of the vision system was conducted in the lab to establish performance envelopes and data processing algorithms to extract the needed information from the captured vision scene. Subsequently, the monitoring apparatus was installed in the vicinity of the Vincent Thomas Bridge in the metropolitan Los Angeles region. This allowed the deployment of the instrumentation system under realistic conditions so as to determine field implementation issues that need to be addressed. It is shown that the proposed approach has the potential of leading to an economical and robust system for obtaining direct, simultaneous, measurements at several locations of the displacement time histories of realistic infrastructure systems undergoing complex three-dimensional deformations.

– Wahbeh, M., Masri, S., Caffrey, J.P., (2003), “Direct Measurement of Displacement in Vibrating Structures Through Vision-Based Approaches”, Proc the 9th ASEC, Abu-Dhabi, UAE, Dec. 2003.

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Direct Measurement of Displacements in Vibrating Structures Through Vision-Based Approaches, 2004 A. Mazen Wahbeh et al.

– Wahbeh, A.M., Caffrey, J.P., and Masri, S.F., (2004), “Direct Measurement of Displacements in Vibrating Structures Through Vision-Based Approaches,” Emirates Journal for Engineering Research, 9 (2), 105-110 (2004).

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Dust Control for Secondary Limestone Roads Using Bentonite, 1990 A. Mazen Wahbeh

– Wahbeh, A.M., 1990. “Dust Control for Secondary Limestone Roads Using Bentonite”, Engineering Research Institute, Iowa State University, Ames, Iowa.

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Dynamic Testing of Alfred Zampa Memorial Bridge, 2008 A. Mazen Wahbeh et al.

Abstract:

This paper describes a set of dynamic field tests performed on the Alfred Zampa Memorial Bridge (AZMB), also known as the New Carquinez Bridge, which is located 32km northeast of San Francisco on interstate Highway I-80. The AZMB, opened to traffic in November 2003, is the first suspension bridge in the United States with an orthotropic steel deck, reinforced concrete towers, and large-diameter drilled shaft foundations. The dynamic field tests described herein were conducted just before the bridge opening to traffic. They included ambient vibration tests, mainly wind induced, and forced vibration tests based on controlled traffic loads and vehicle-induced impact loads. Four different controlled traffic load patterns and seven different vehicle-induced impact load configurations were used in the forced vibration tests. The dynamic response of the bridge was measured through an array of 34 uniaxial and 10 triaxial force-balanced accelerometers deployed along the whole length of the bridge. These dynamic field tests provided a unique opportunity to determine the dynamic (modal) properties of the bridge in its as-built (baseline) condition with no previous traffic loads or seismic excitation. Such properties could be used to validate and/or update the finite element models used in the design phase of this bridge. They could also be used as baseline for future health monitoring studies of this bridge. At the end of the paper, the ambient vibration test data were used to identify the bridge modal parameters (natural frequencies, damping ratios, and mode shapes) using the data-driven stochastic subspace identification method.

– Conte, J.P, He, X., Moaveni, B., Masri, S.F., Caffrey, J.P., Wahbeh, M., Tasbihgoo, F., Whang, D.H., and Elgamal, A., (2008), “Dynamic Testing of Alfred Zampa Memorial Bridge,” ASCE Journal of Structural Engineering, Vol 134, No 6, pp 1006-1015.

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Effect of Surface Evaporation and Slab Thickness on the Scaling Resistance of Concrete Containing Fly Ash, 2005 Jinesh Mehta et al.

Abstract:

Laboratory tests (conducted in accordance with ASTM C 672) frequently indicate that concrete containing fly ash may be susceptible to scaling. Based on this concern, a few northern USA states restrict the use of fly ash during the late-fall pavement construction season. However, a survey of twelve northern states revealed that scaling is rarely observed in actual pavements. In an attempt to develop a more clear understanding of the potential reasons for the apparent discrepancy between the scaling resistance of laboratory concretes and field concretes, scaling studies were conducted on concrete containing 20% of a Class C fly ash. The main variables in the study were the surface water evaporation rate (water loss was ranged from 0 to 4.5 kg/sq m 2) and the thickness of the slab specimen (55 mm to 245 mm). The selected ranges of test variables were intended to represent moisture and temperature conditions that are likely to be encountered in the field. In addition to monitoring the mass of material lost from the surface due to scaling, the temperature gradient that developed inside the specimen during freezing was measured. In addition, scanning electron microscopy was performed to assess differences in porosity of the near surface concrete. The results indicate that ASTM C 672 is too severe when compared to the environmental conditions that are likely to be encountered in the field.

– J. Mehta, J. Olek, J. Weiss, and T. Nantung, “Effect of Surface Evaporation and Slab Thickness on the Scaling Resistance of Concrete Containing Fly Ash”, Eighth International Conference on Concrete Pavements, August 2005.

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Feasibility of Detecting Known Structural Changes From Ambient Bridge Vibration Data, 2001 A. Mazen Wahbeh et al.

– Nigbor, R, Masri, S.F, Smyth, A, Wahbeh, A., and Wait, J, (2001), “Feasibility of Detecting Known Structural Changes From Ambient Bridge Vibration Data,” Proc the 3rd Intl Workshop on Structural Health Monitoring, Stanford, September 2001.

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Full-Scale Dynamical Testing of the Alfred Zampa Memorial Bridge, 2006 A. Mazen Wahbeh et al.

– Wahbeh, A.M., Caffrey, J.P., Tasbihgoo, F., Masri, S.F., Conte, J., He, X., Moaveni, B., and Elgamal, A., (2006), “Full-Scale Dynamical Testing of the Alfred Zampa Memorial Bridge,” Proc of Tenth Arab Structural Engineering Conference (10ASEC), 16-18 November 2006, Kuwait.

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Implementation of Real-Time and Vision-Based Structural Health Monitoring of Long-Span Bridges, 2005 A. Mazen Wahbeh et al.

– Wahbeh, M, Masri S F, Caffrey, J P, and Sheng, L-H, (2005), “Implementation of Real-Time and Vision-Based Structural Health Monitoring of Long-Span Bridges,” Proc Second International Conference on Structural Health Monitoring of Intelligent Infrastructure SHMII-2 ’2005. Shenzhen, China, 16-18 November 2005.

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Innovation in Fabrication of the Self-Anchor Suspension Span of the San Francisco-Oakland Bay Bridge, 2010 A. Mazen Wahbeh et al.

Abstract:

The 2.2-mile-long East Span of the San Francisco-Oakland Bay Bridge (SFOBB) is currently undergoing a seismic retrofit that will completely replace the existing steel truss bridge that opened in 1936. Approximately 280,000 vehicles cross the SFOBB daily and the bridge corridor is being brought up to current seismic safety standards by replacing the existing East Span. This work is being accomplished while keeping the existing bridge open to traffic. A key component of the New East Span will be a Self-Anchored Suspension (SAS) bridge chosen by the region and legislated to be the signature span in the retrofit of one of the nation’s busiest bridges. When complete, this structure will be the world’s largest SAS. American Bridge/Fluor Enterprises (AB/F) (A Joint Venture) won the bid to build the SAS. Both companies have impressive portfolios combining years of experience that include constructing the original SFOBB. AB/F determined that the structural steel portion of the SAS would be fabricated in China at the Shanghai Zhenhua Heavy Industry Co. Ltd. (ZPMC), a subsidiary of the China Communication Construction Company (CCCC) on Changxing Island just outside Shanghai. ZPMC is the largest heavy-duty equipment manufacturer in the world and is famous for producing more than 75 percent of the world’s port cranes used in the shipping industry as well as other large scale steel bridges such as the Golden Ears Bridge in Vancouver, Canada. ZPMC implemented a number of innovations in order to expedite the fabrication process and to assure meeting the stringent quality requirements of what will soon be a world-renowned architectural icon while remaining the backbone of regional transportation in the San Francisco Bay Area.

– Wahbeh, M., Siegenthaler, P., Nilsson, T., Nader, M., and Cavendish-Tribe, A. (2010), “Innovation in Fabrication of the Self-Anchor Suspension Span of the San Francisco-Oakland Bay Bridge,” Proc International Bridge Conference, June 2010, Pittsburgh, PA, USA.

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Innovations in the Production of the Seismic Members of the Self Anchored Suspension San Francisco Oakland Bay Bridge, 2013 A. Mazen Wahbeh et al.

Abstract:

The 2.2-mile-long East Span of the San Francisco-Oakland Bay Bridge (SFOBB) is currently undergoing a seismic retrofit that will completely replace the existing steel truss bridge that opened in 1936.  Approximately 280,000 vehicles cross the SFOBB daily.  The bridge corridor is being brought up to current seismic safety standards by replacing the existing East Span.  This work is being accomplished while keeping the existing bridge open to traffic.  A key component of the New East Span will be a Self-Anchored Suspension (SAS) bridge, chosen by the region to be the signature span in this retrofit of one of the nation’s busiest bridges.  When complete, the structure will be the world’s largest SAS.  Several innovations were implemented to expedite the fabrication process of seismic members of the bridge tower and to assure meeting the stringent quality requirements of what will soon be a world-renowned architectural icon in the San Francisco Bay.

This paper will discuss production innovations implemented to facilitate fabrication of the seismic members within the budgeted cost while ensuring that the required quality standards and aggressive schedule were met.  During fabrication, the California Department of Transportation (Caltrans) implemented the use of non-destructive techniques to assure the quality of structural steel members.  Meanwhile, constant and open communication between the stakeholders throughout the duration of the project led to proactive solutions to anticipated issues.  Furthermore it was determined early on that the production of half-scale and full-scale mock-ups would be instrumental for the complicated seismic performance of members.

– Mazen Wahbeh, Nina Choy, Gary Thomas, Aaron Prchlik, Laura Webb and James Reid (2013). “Innovations in the Production of the Seismic Members of the Self Anchored Suspension San Francisco Oakland Bay Bridge,” 7th National Seismic Bridge Conference, Oakland, California.

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Large-Scale Dynamical Testing of the Alfred Zampa Memorial Suspension Bridge, 2006 A. Mazen Wahbeh et al.

Abstract:

This paper describes a set of dynamic field tests performed on the Alfred Zampa Memorial Bridge (AZMB), also known as the New Carquinez Bridge, which is located 32km northeast of San Francisco on interstate Highway I-80. The AZMB, opened to traffic in November 2003, is the first suspension bridge in the United States with an orthotropic steel deck, reinforced concrete towers, and large-diameter drilled shaft foundations. The dynamic field tests described herein were conducted just before the bridge opening to traffic. They included ambient vibration tests, mainly wind induced, and forced vibration tests based on controlled traffic loads and vehicle-induced impact loads. Four different controlled traffic load patterns and seven different vehicle-induced impact load configurations were used in the forced vibration tests. The dynamic response of the bridge was measured through an array of 34 uniaxial and 10 triaxial force-balanced accelerometers deployed along the whole length of the bridge. These dynamic field tests provided a unique opportunity to determine the dynamic (modal) properties of the bridge in its as-built (baseline) condition with no previous traffic loads or seismic excitation. Such properties could be used to validate and/or update the finite element models used in the design phase of this bridge. They could also be used as baseline for future health monitoring studies of this bridge. At the end of the paper, the ambient vibration test data were used to identify the bridge modal parameters (natural frequencies, damping ratios, and mode shapes) using the data-driven stochastic subspace identification method.

– Mazen Wahbeh, Sami Masri, John Caffery, Farzad Tasbihgoo, and Joel Conte (2006). “Large-Scale Dynamical Testing of the Alfred Zampa Memorial Suspension Bridge,” Third International Conference on Bridge Maintenance, Safety and Management. July 16-19, 2006, Porto-Portugal.

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Long-Term Monitoring of the Stochastic Characteristics of a Full-Scale Suspension Bridge, 2008 A. Mazen Wahbeh et al.

– Yun, H-B., Masri, S.F., Nayeri, R., Tasbihgoo, F., Kallinikidou, E., Wahbeh, M, Wolfe, R., and Sheng, L-H., (2008), “ Long-Term Monitoring of the Stochastic Characteristics of a Full-Scale Suspension Bridge,” Proc Fourth International Conference on Bridge Maintenance, Safety and Management, IABMAS08 Conf, 14-17 July 2008, Seoul, Korea.

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Monitoring the Collision of a Cargo Ship with the Vincent Thomas Bridge, 2007 A. Mazen Wahbeh et al.

Abstract:

On 27 August 2006, the Vincent Thomas Bridge, a 1850-m suspension bridge located in the larger metropolitan Los Angeles region, was struck by a large cargo ship passing under the bridge. Moderate damage to the maintenance scaffolding at the main span of the bridge was observed. This incident left transportation authority’s wondering about the structural integrity of the bridge. A real-time continuous monitoring system that had been recently installed on the bridge successfully recorded dynamic response before and after the incident, as well as during the collision. Analysis of these valuable data allows transportation authorities to quantify the effects of the collision on the bridge structural condition, which would otherwise be infeasible with traditional visual bridge inspection approaches. A forensic study was performed to assess the structural condition of the bridge before and after the incident. Both global (multi-sensor) and local (single-sensor) identification methods were applied to detect whether significant changes occurred in the bridge vibration signature.

– Yun, H., Nayeri, R., Tasbihgoo, F., Wahbeh, M., Caffrey, J., Wolfe, R., Nigbor, R., Masri, S., Abdel-Ghaffar, A., and Sheng, L; (2007), “Monitoring the Collision of a Cargo Ship with the Vincent Thomas Bridge,” Journal of Structural Control and Health Monitoring, Volume 15, Issue 2, March 2008, Pages: 183-206.

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Monitoring the Vibrations of Dispersed Civil Structures Through the Use of a Vision-Based Method, 2004 A. Mazen Wahbeh et al.

Abstract:

This paper reports the results of an analytical and experimental study to develop, calibrate, implement and evaluate the feasibility of a novel vision-based approach for obtaining direct measurements of the absolute displacement time history at selectable locations of dispersed civil infrastructure systems such as long-span bridges. The measurements were obtained using a highly accurate camera in conjunction with a laser tracking reference. Calibration of the vision system was conducted in the lab to establish performance envelopes and data processing algorithms to extract the needed information from the captured vision scene. Subsequently, the monitoring apparatus was installed in the vicinity of the Vincent Thomas Bridge in the metropolitan Los Angeles region. This allowed the deployment of the instrumentation system under realistic conditions so as to determine field implementation issues that need to be addressed. It is shown that the proposed approach has the potential of leading to an economical and robust system for obtaining direct, simultaneous, measurements at several locations of the displacement time histories of realistic infrastructure systems undergoing complex three-dimensional deformations.

– Wahbeh, A.M., Caffrey, J.P., and Masri, S.F., (2004), “Monitoring the Vibrations of Dispersed Civil Structures Through the Use of a Vision-Based Method,” Proc of the Third European Conference on Structural Control, 3ECSC, 12-15 July 2004, Vienna University of Technology, Vienna, Austria.

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Non-Destructive Testing Challenges for the California Toll-Bridge Seismic Retrofit Program, 2000 A. Mazen Wahbeh et al.

Abstract:

This paper discusses the numerous nondestructive testing (NDT) challenges encountered during the seismic retrofit of California’s toll bridges. The California Department of Transportation (Caltrans) has implemented a $4 billion statewide seismic retrofit program. The main focus of this program is seven large toll bridges. The San Diego-Coronado Bay Bridge and the San Mateo-Hayward Bridge, two specific examples of the seven major toll bridges, are discussed in this paper. Multiple NDT methods were utilized in order to assure that the welding on these projects met the design specifications. The major components of the retrofit of the San Diego-Coronado Bay Bridge were the “Pin-Assemblies” which required developing special ultrasonic testing procedures in order to verify the soundness of these critical complete penetration welds. The unique design of these assemblies required a high level of NDT evaluation. On the other hand the San Mateo-Hayward Bridge retrofit required welding of several 160-ft (48.8-m) long steel pipe pilings which ranged in diameter from 5 to 12 ft (1.52 to 3.66 m). This paper discusses the procedures employed to select the most useful NDT method to evaluate the complete penetration welds as well as the interesting challenges posed by the ultrasonic testing of the longitudinal welds on the smaller diameter steel pipe pilings. In both of the aforementioned examples, numerous NDT problems were encountered. This paper discusses these issues in detail.

– Wolfe, R.W., Wahbeh A.M., (2000) “Non-Destructive Testing Challenges for the California Toll-Bridge Seismic Retrofit Program.” Proc of the Fourth Structural Materials Technology, Feb. 20-23, 2000, pp 165-170, Atlantic City, New Jersey.

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Real-Time Earthquake Monitoring of Large-Scale Bridge Structures, 2005 A. Mazen Wahbeh et al.

– Wahbeh, M, Tasbihgoo, F, Yun, H, Masri, S F, Caffrey, J P, and Chassiakos, A G, (2005), “Real-Time Earthquake Monitoring of Large-Scale Bridge Structures,” Proc 5th International Workshop on Structural Health Monitoring, Stanford University, California, September 2005.

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Real-Time Monitoring of Large-Scale Bridge Structures, 2005 A. Mazen Wahbeh et al.

– Wahbeh, M., Masri, S., (2005), “Real-Time Monitoring of Large-Scale Bridge Structures,” Proc 3rd International Conference Construction Materials Performance, Innovations and Structural Implications, ConMat’05, Vancouver, Canada, August 22-24 2005.

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