The Application of Real-Time Monitoring Systems on Long-Span Truss Bridges:

I. Abstract

Structural identification incorporates objective conditions, performance data of a structure in both global and local levels, identifies reliable 3-D models, while enabling realistic decisions. Long span trusses lack data analysis and experimental expertise in their structural identification. As a result, long term health monitoring systems are placed to track and identify complications to withstand conditions such as: regulating features from weather conditions, incident responses, and weight-based assessments. Specifically in this report, the Commodore Barry Bridge (4,240 m span) is examined by analyzing sensor systems placed in various locations, while exploding 3-D modeling using applications of AutoCAD. The monitoring system consisted of eighty channels of different sensor types, to allow for various data collecting on the truss bridge to be viewed from one remote location. Results have proven the substantial benefits in uses of these systems, in enabling a proper framework for processing experimental data. For future analysis and stored information in long span truss bridges, this technology can create improved long term savings in construction costs with the help of engineers and technicians.

II. Introduction

As we know today, bridges are one of the major roadworks used to transport people and goods over a body of water or land. Much work goes into the construction of proper bridges, where civil engineers design durable structures to facilitate a safe and efficient flow. A truss bridge consists of members organized into connected manufactured steel bars made up of triangular patterns that behave as a single object. These are coupled at joints known as fixed nodes to create a secure, rigid structure. The key component of its functionality is to provide long term durability and lasting effects to withhold extreme conditions over the years. These truss bridges have members organized to behave without bending or shearing. This reduces deflection (where an element can change its shape when a large load is applied). This is positive in that with load intensity, the shape and material of the members stay intact. In its longevity, the amount of materials needed are minimized, while the system is overall efficient and forces are distributed among a number of members.

In its entirely, long-span structural trusses are typically 500 m or longer and are able to support heavy loads. Certain attributes, such as: higher ratio of dead-load demands, significance of wind loads, size and testing, and low global response frequencies affect their structural habits in their functionalities (Nguyen, 2018). To track and evaluate structural performance to avoid future challenges, real time bridge health monitoring systems need to be implemented. There is an overall shortage in data analysis and expertise in structural identification of long-span truss bridges. These monitoring data systems can be integrated into assessing and performing predictions by introducing concepts of statistics in extremes. This information is highly useful for engineers and technicians in evaluating key concepts in these constructions.

In this report, a long-span truss bridge known as the Commodore Barry Bridge (one of the longest cantilever truss bridges in the US, 4,240 m), is examined to grow knowledge in the uses of these health monitoring systems. As, “improved operational performances, reduced life-cycle maintenance costs and effective rehabilitation and retrofits, is substantial” (Aktan, 2000). Using 3-D modeling, provides a basis to see how this technology can provide real time factual information in (Hz), projected to show global frequencies in movement and analytical data.

II. Purpose

The purpose of this report is to portray how structural identification can bring light to the effective uses of health-monitoring systems in long span truss bridges. Long span bridges have very different applications from short-span bridges in their utilization. In this, my target audience are engineers and technicians who will work on the constructions of these bridges in future times. Learned information in the uses of this effective technology, will help in modeling and fixating foundations projected in these types of bridges. Similarly to this, this report looks at the structural identification processes for the Commodore Barry Bridge (CBB), while providing optical integration in experimental and analytical components.

III. Body 

i. Concept of Structural Identification & Uses

Structural identification relies on the use of field onsite observations, measurements, and controlled experiments. This can provide analysis on structural condition and behaviors in certain environments of these bridges. The purpose in this is to see how civil engineering systems interact with social systems, while attaining global and local responses. Structures deal heavily in factors such as: their geometry, support, connectivity, stiffness, and kinematics (Aktan, 2000). This creates an understanding when measuring data as to how damage indicators are created, showing how the structure may perform in its advanced limited states. This goes way beyond traditional analysis of simplified models in investigations. In its influence, this structural identification can track damage such as freezing in formations, while addressing future constructions. 

ii. Structural Identification of the Commodore Barry Bridge (CBB)

Figure 1.1: Experimental Tools for Structural Identification

* Figure 1.1 presents a simple example of the concepts of structural loading system identification. This can be very complex, however it is important to visualize and conducting great tests, to obtain successful data information. This knowledge built upon can give significant results in decision and management applications. It is best to follow this chart in determining results in analysis of long span truss bridges.

When looking solely at the Commodore Barry Bridge (CBB), it is best to observe how this structural identification can be applied. Engineering related decisions can be looked at from a model that describes field calibrated components that enable structural responses.This is in relation to loading effects such as: possible operations, maintenance, and challenges in performance of bearing systems (Refer to figure 1.1).

iii.  Conceptualize/Visualizing (Structural Modeling in 3-D AutoCAD)

Referenced in figure 1.1: the essential takeaway is to determine how to conceptualize these structural systems in a way to fully understand their functions and how they are built. This is done through three-dimensional (AutoCAD software), computer drawings. AutoCAD is a unique drawing software that enables to envision structures, enabling one to see all the components such as: bearings, pins, stinger spans, and deck truss visually. Rocker bearings that contributed in longitudinal movements and prevented vertical uplift, were utilized at the extremities. Fixed bearings were used at the tower connections with concrete piers. The floor system presented as a thick reinforced concrete deck with underlying stingers supported on plate girder floor beams. These underlying stringers were created to isolate floor beams from longitudinal movements. In addition, other primary systems were located throughout the structure: such as traffic signs, access elevators, maintenance walkways, railing and barrier systems (Aktan, 2000). In the analytical model (see figure 1.2), links and constraints were used to restore the 3-D geometry in connection. Foundations such as: out of plane members, frames, and braces were additionally incorporated. Statistics provide mathematical elements to the bridge, identified through mechanisms of AutoCAD.

Figure 1.2: 3-D AutoCAD model of Commodore Barry Bridge

*It is important to note that when presented with an analytical-model, there are certain parameters that need to be fully considered. Being that the bridge is very complex in its behavior, the bridge is not necessarily posed to be symmetrical. It can be seen that sizing models to be exact, can be placed as a challenge when properly displaying behavior in these long-span bridges.

iv.Implementation of Health-Monitoring Systems

Through the use of AutoCAD drawings, one can identify potential locations for health-monitoring systems to be placed. A health monitoring system is the most effective tool for advancing applications in long-span bridges. Presented with the CBB, a core global monitoring system was placed in which permanent sensors were installed and periodic tests were conducted. For example, technicians were able to use this system to perform controlled crawl and stationary load tests on the bridge, using heavy trucks to evaluate critical responses of the floor and truss systems (Aktan, 2000). These monitoring systems can produce great effective results. For example, helping to: establish node shapes of the structure, analyze wind and temperature inputs, find ways to respond to traffic related inputs, or understand fundamental geometric features in the structure.

v.Effective Methods of Use in CBB

In the utilization of the monitoring system, two primary modes were performed to operate. The first consisted of continuous slow speed scans (1 Hz) of wind speed, images, and temperatures at instrumented locations. The second mode was a high speed scan (75 Hz) of strain and accelerations. These monitoring system sensors were placed on the most geometrically symmetric regions of the truss bridge. To transmit the information, installations of cabling systems linked the central data located on one of the piers. The base system is said to record about eighty channels of data to accommodate a higher number of information signals. These sensor types included: VW Strain Gauges, Resistive Strain Gauges,Accelerometers, a Video Camera, and Anemometers placed throughout panels of the truss (see figure 2.1).  As stated above, these types of sensor signal different rates of frequency in reaction times. Data processing includes different parameters of: image processing with pattern recognitions, visualization, time stamping and format conversion, archiving, and mining (Aktan, 2000).

Figure 2.1: Monitor System Types and Locations

vi.Live Integration of these Images and Data Inquisition

As seen above, operational and structural maintenance is essential in taking advantage of weather conditions, heavy traffic loads, incidents, engineering inspections or maintenance activities linked to operations (Aktan, 2000). This monitoring system can present a great opportunity to explore designs and apply structural engineering tactics in attaining high maintenance. These systems present real-life image and strain responses from members in frequencies. In addition, wind and temperature environment information is introduced, being highly advantageous in understanding foundational changes to its structure. This is done through wind sensors located on the top and bottom of chords, where ambient temperatures and wind velocity can be measured. This is critical in responding to changing weather conditions and emergencies.

IV. Conclusion

Long-span bridges are used everywhere in the world, however lack strong critical information in their structures as they differ directly from short-span bridges. Structural identification research can help accomplish influential benefits. Visualization of structures using AutoCAD is most helpful to see 3-D components of the system: frames, nodes, elements, etc. From this, methods and processing of experimental data must be implemented. Health monitoring systems, like those used in the Commodore Barry Bridge, provide a common framework as to how environmental and structural objects play a part in their functions. They are very advantageous and should continue to carry additional information in these structures. This technology adds great knowledge to various aspects of operational and maintenance management. Data used from this system can be viewed and examined through a remote location, as various channels provide numerous data collected from different parts of the bridge. Technicians and civil engineers can use information in light of long-term saving costs in constructions. In addition, the use of tolls on these bridges can provide funding for these projects in providing more health monitoring systems.

V. Citations

Aktan, A. (2000, January). Structural Identification of a Long-Span Truss Bridge. Retrieved March 3, 2020, from https://www.researchgate.net/publication/245559047_Structural_Identification_of_a_Long-Span_Truss_Bridge

Nguyen, D. (2018, July 10). Structural Health Monitoring of Long-span bridges . Retrieved March 3, 2020, from https://www.ndt.net/article/ewshm2018/papers/0354-Meng.pdf

Fan, X. P. (2015). Comparisons of prediction models for time-dependent reliability forecasting of bridge structures based on SHM data. Retrieved March 3, 2020, from https://books.google.com/books?id=K9DLBQAAQBAJ&pg=PA543&lpg=PA543&dq=real+life+monitoring+systems+on+long+truss+bridges&source=bl&ots=AJkCOJY8mw&sig=ACfU3U2d4IfiEOvtCPMOed4TkouBjbIssQ&hl=en&sa=X&ved=2ahUKEwiG1aaDwoHoAhVxlnIEHT3cAbgQ6AEwDHoECAsQAQ#v=onepage&q=real%20life%20monitoring%20systems%20on%20long%20truss%20bridges&f=false

Zhang , J. (2013). Experimental Vibration Analysis for Structural Identification of a Long-Span Suspension Bridge. Retrieved March 8, 2020, from https://www.researchgate.net/profile/Jian_Zhang402/publication/315741279_Experimental_Vibration_Analysis_for_Structural_Identification_of_a_Long-Span_Suspension_Bridge/links/58e10d5d4585153bfe9a21cb/Experimental-Vibration-Analysis-for-Structural-Identification-of-a-Long-Span-Suspension-Bridge.pdf

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Individual Techniques in the Brainstorming Process:

The writing process for my technical report was a learning experience, being very informative. Considering that it was my first time writing this report, I had attained further writing techniques. In prior years, I have had the chance to write my own research paper. This generally was very similar in formatting aspects to the technical report. My main focus in writing this technical report was: structural identification and its applications of using health monitoring systems to portray real-time information to reach future engineers and technicians. Computer software such as 3-D modeling such as AutoCAD, can provide realistic features to these structures. I have applied this information to evaluate my topic in its subcategory of civil engineering. 

I knew I wanted to specify my search on truss bridge designs. However, narrowing my search on this broad topic posed a challenge. I began by searching for articles that would hold enough useful information (provided with diagrams and pictures), that would help heavily influence my thoughts on these applications. Seeking further knowledge into these designs, I became aware that my original thoughts on simple trusses (from the technical description) would need to be expanded on. I wanted to dive deeper into other models and find unique habits that can connect or portray characteristics to all truss types. 

This brainstorming process was long and extensive. My main concern was formatting my thoughts effectively, to reach my point of view and objective in comprehension. In the beginning, I was continuously unsure of how to organize the quantity of information. My first step consisted of creating subheadings and titles, to gather thoughts from research and scientific articles. I knew that my report generally needed to contain: an abstract, introduction, body, conclusion, and section of references. Yet, upon writing I faced several challenges. My biggest struggle was narrowing down my purpose, while having to establish a target audience that would find this knowledge most useful. Upon further reading, I came to a conclusion that this material is pronounced to be most practical for future technicians and civil engineers (like myself). 

The reviewing process was helpful, in that Professor McDonald allowed me to understand what needed to be added to my previous draft. Most importantly from my first draft: a purpose section entirely had been missing. This would help readers to understand my target audience and the general purpose for writing this report. Previously, this information had been added more to my introduction section, however did not consist of its own section in the report. Professor McDonald had explained that including this section is essential in allowing for clear comprehension before continuing to address any extra information. In addition, using subheadings in bolded text is key in sorting information for the reader to be able to go back specifically to one section of the report when needed. Figures portrayed throughout, enabled to visualize points made throughout the paper in reference to the knowledge learned. 

Writing this technical report was advantageous in teaching ways to allow me to display information in my level of expertise. Research allowed me to dig deeper into my topic, in comparison to the technical description. From my first draft to the final: information is clearly depicted, arranged properly, and visually appealing in full apprehension.