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S A M 1- Develop SHM Plan

This educational module focuses on developing a SHM plan for a highway sign structure. Students will learn how to organize specifications, defend the suitability of the plan, and produce a template for recording SHM data.

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S A M 1- Develop SHM Plan

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  1. SAM 1- Develop SHM Plan Application Education Subunit- Structural Health Monitoring Education Unit

  2. Expected Learning Outcomes • To be able to sketch a SHM plan for a specific project. • To be able to organize a set of specifications for a specific project. • To be able to defend the suitability of the developed SHM plan for achieving the project’s goal. • To be able to produce a template for recording SHM data. Application Education Subunit- Structural Health Monitoring Education Unit

  3. Your Assignment (Web-based Exams) • After you have read and reviewed the content provided, you will be required to: • Take an online readiness exam to determine if you have achieved a satisfactory understanding of the content of SAM1 to engage in a discussion. • Submit an online response to several questions related to the content of this module and list any questions you might have concerning anything you might not understand about the material. • The online responses will be discussed in an interactive manner in a classroom setting on the date indicated on the Master Schedule. Application Education Subunit- Structural Health Monitoring Education Unit

  4. Your Assignment (Paper Exams) • After you have read and reviewed the content provided, you will be required to: • Take a readiness exam to determine if you have achieved a satisfactory understanding of the content of SAM1 to engage in a discussion. • Submit a response to a discussion question related to the content of this module and list any questions you have concerning anything you might not understand about the material. • Student responses to the discussion question will be discussed in an interactive manner in a classroom setting on the date indicated on the Master Schedule. Fundamentals Education Subunit- Structural Health Monitoring Education Unit

  5. Deadlines • Deadline for completion of assignment: TBD • Date of classroom discussion of online responses: TBD Application Education Subunit- Structural Health Monitoring Education Unit

  6. The Purpose • The purpose of this education module is to expand your knowledge base on the topic of SHM. • You will learn: • How to implement a SHM system based on what you have learned in SEM2. • How to produce a set of specifications and drawings ready for execution. Application Education Subunit- Structural Health Monitoring Education Unit

  7. The Projects (1) • In this module, you will deal with three SHM projects. • Each of the projects has a different objective and is for a different type of structure: • Highway Sign Structure • Pre-Stressed Concrete Bridge Girder • Buried Reinforced Concrete Box Culvert Application Education Subunit- Structural Health Monitoring Education Unit

  8. The Projects (2) • You will not be asked for developing a complete instrumentation plan for each of these projects. • Developing such instrumentation plans is very involved and needs time and collaboration of many parties to make decisions. • Instead, you will be asked specific questions of what you think the correct approach should be. Application Education Subunit- Structural Health Monitoring Education Unit

  9. The Projects (3) • For example, you will be asked what type of sensors should be used to achieve the goal of the project and where you think they should be installed. • Critical stresses typically happen at the locations subjected to largest bending moments, shear forces, and, in some cases, torsional moments. • Vibrations tend to happen at locations where the structures experience the maximum deformations under the exciting force. Application Education Subunit- Structural Health Monitoring Education Unit

  10. Project #1: HIGHWAY SIGN STRUCTURE (1) • Highway signs are essential for guiding motorists on highways. • In addition to alerting drivers to speed limits, directions, and distances to certain destinations, they also inform them of detours, construction work, and hazards, such as sharp turns and steep hills. • In other words, they are essential for the safety of everyone using the highway. Application Education Subunit- Structural Health Monitoring Education Unit

  11. Project #1: HIGHWAY SIGN STRUCTURE (2) • Like any other structure, highway signs are structures that can suffer from overloads, fatigue issues, and vibrations. • They are also susceptible to damage by impact from vehicles veering of the road. • In addition to not providing the important information that a sign normally would, their failure can be hazardous if they end up on the road as can be seen in the figure on the left. Application Education Subunit- Structural Health Monitoring Education Unit

  12. Project #1: Project Goal • The goal of this project is twofold. • For the structure on the right, you are asked to do the following. • Determine critical stress levels in the mast. (Stress History Test) • Understand the characteristics of vibrations happening in the structure. (Ambient Vibration Test) Application Education Subunit- Structural Health Monitoring Education Unit

  13. Project #1: Instrumentation Plan Questions (1) Determining Sensor Locations • To determine the critical sensor locations for this structure, whose mast can be subjected to large torsional moments, you will have to: • Qualitatively sketch the straining action diagrams caused by the shown wind force, , and self weight of the sign, , only. • Ignore other loads such as self-weight, etc. • No calculations are necessary, just a sketch to help you identify where the maximum values take place. Application Education Subunit- Structural Health Monitoring Education Unit

  14. Project #1: Instrumentation Plan Questions (2) Determining Sensor Locations • Sketch the following on the figures given and mark the critical sections. • Shear Force Diagram (SFD) • Bending Moment Diagram (BMD) • Torsional Moment Diagram (TMD) • Normal Force Diagram (NFD) is provided to help refresh you memory. Application Education Subunit- Structural Health Monitoring Education Unit

  15. Project #1: Instrumentation Plan Questions (3) NFD Application Education Subunit- Structural Health Monitoring Education Unit

  16. Project #1: Instrumentation Plan Questions (4) SFD in y-z plane Application Education Subunit- Structural Health Monitoring Education Unit

  17. Project #1: Instrumentation Plan Questions (5) BMD in y-z plane Application Education Subunit- Structural Health Monitoring Education Unit

  18. Project #1: Instrumentation Plan Questions (6) TMD @ z-axis Application Education Subunit- Structural Health Monitoring Education Unit

  19. Project #1: Instrumentation Plan Questions (7) • For a cantilever type structure such as this sign structure, it is easy to envision which part will deflect the most under the shown forces. • Mark the locations of maximum deflection for this cantilever structure. Application Education Subunit- Structural Health Monitoring Education Unit

  20. Project #2: Pre-Stressed Concrete Bridge (1) • Bridge overpasses are an integral part of any transportation network, especially congested cities as they reduce intersections and allow smoother traffic flow. • Because of their proven record, the large majority of bridge overpasses are nowadays constructed using pre-stressed concrete. • They are durable, cost effective, and structurally capable of resisting the always increasing heavy loads that drive on highways. Application Education Subunit- Structural Health Monitoring Education Unit

  21. Project #2: Pre-Stressed Concrete Bridge (2) Application Education Subunit- Structural Health Monitoring Education Unit

  22. Project #2: Pre-Stressed Concrete Bridge (3) • All structures can suffer from failures of their conditions. • For pre-stressed concrete, these conditions can be corrosion of the internal reinforcement (pre-stressing strands), fatigue or deterioration of the concrete itself, increase in applied loads, or inadequate design. • Without proper inspection and mitigation measures, catastrophic failures can happen as can be seen in the following figures. Application Education Subunit- Structural Health Monitoring Education Unit

  23. Project #2: Pre-Stressed Concrete Bridge (4) Application Education Subunit- Structural Health Monitoring Education Unit

  24. Project #2: Project Goal (1) There are two concerns about the concrete slab-on-girder bridge to be evaluated in this project: • One of the girders has two cracks as can be seen. • The flexural crack is stable and not much of a concern. • The concern is about the shear crack, which inspection reports showed that it may be growing. • Engineers were concerned about the flexural capacity of the girders. Application Education Subunit- Structural Health Monitoring Education Unit

  25. Project #2: Project Goal (2) Based on this information, you are asked to do the following: • Determine whether the width of the shear crack is still growing or not. (Periodic Monitoring Test) • Estimate the girder’s flexural response under a given test load. (Behavior Test) Application Education Subunit- Structural Health Monitoring Education Unit

  26. Project #2: Project Goal (3) Elevation of bridge girder showing cracks. Application Education Subunit- Structural Health Monitoring Education Unit

  27. Project #2: Project Goal (4) Bridge cross section. Application Education Subunit- Structural Health Monitoring Education Unit

  28. Project #2: Instrumentation Plan Questions (1) Determining Sensor Locations • Even though the bridge is a three-dimensional (3D) structure, we can think of each girder as a simple line beam that you are familiar with from your structural analysis course. • With this assumption, you can sketch qualitative straining action diagrams caused by the given loads: • Self weight of the bridge (uniformly distributed). • Truck load, which can be approximated as a point load for simplicity. Application Education Subunit- Structural Health Monitoring Education Unit

  29. Project #2: Instrumentation Plan Questions (2) Determining Sensor Locations • No calculations are necessary, just a sketch to help you identify where the maximum values take place. • Sketch the Shear Force Diagram (SFD) and Bending Moment Diagram (BMD) for the shown typical loads (uniform self weight and dump truck approximated with one point load) on the figures in the following slides. Application Education Subunit- Structural Health Monitoring Education Unit

  30. Project #1: Instrumentation Plan Questions (3) Approximate Loads Application Education Subunit- Structural Health Monitoring Education Unit

  31. Project #1: Instrumentation Plan Questions (4) SFD BMD Application Education Subunit- Structural Health Monitoring Education Unit

  32. Project #2: Instrumentation Plan Questions (5) • For a simply supported beam like our bridge girders, it is easy to envision which of the two cracks is caused by shear (our target) and which is caused by flexure (not part of our scope). • We can also identify the critical section for assessing the flexural behavior. Application Education Subunit- Structural Health Monitoring Education Unit

  33. Project #1: Instrumentation Plan Questions (6) Cross Section Possible Orientations Application Education Subunit- Structural Health Monitoring Education Unit

  34. Project #1: Instrumentation Plan Questions (7) • Mark the location of your proposed sensors for the simply-supported bridge girder. Girder Elevation (Note: Only the left half of the beam is shown.) Application Education Subunit- Structural Health Monitoring Education Unit

  35. Project #2: Instrumentation Plan Questions (8) After you have identified the sensor location, answer this question. • Recommend the type of sensor that should be used for both goals of the project (shear crack and flexural capacity). Bonus Question: • For monitoring the shear crack growth, what would be the orientation of the sensor that you would use? Application Education Subunit- Structural Health Monitoring Education Unit

  36. Project #3: Buried Box Culvert (1) • Culverts are tunnel-like structures that are buried under roadways. • They are surrounded by soil all around, however, the depth of the top layer of soil can vary greatly including the possibility of having no soil over the culvert, just underneath it and on its side. • In this latter case, the top surface of the culvert also serves as the roadway. Application Education Subunit- Structural Health Monitoring Education Unit

  37. Project #3: Buried Box Culvert (2) • The main purpose of adding culverts to highway projects is to provide cross drainage in an engineered way. • They come in various shapes such as arch culverts, pipe culverts, and box culverts that can be built using concrete, metal (typically corrugated metal sheets), or PVC. Application Education Subunit- Structural Health Monitoring Education Unit

  38. Project #3: Buried Box Culvert (3) Two-Cell Box Culvert Three-Cell Pipe Culvert Application Education Subunit- Structural Health Monitoring Education Unit

  39. Project #3: Buried Box Culvert (4) • Even though most culverts are buried under a soil layer, they may still experience heavy traffic loads that attenuate through the soil to the culvert. • They can also be subjected to large hydraulic forces when water levels are high. • Failures of buried culverts are not unheard of. When they do happen, the roads become impassable. Therefore, we have to make sure that their structural integrity is maintained at all times. Application Education Subunit- Structural Health Monitoring Education Unit

  40. Project #3: Buried Box Culvert (5) Application Education Subunit- Structural Health Monitoring Education Unit

  41. Project #3: Project Goal (1) • The real behavior of a buried culvert is affected by the fact that it is a three-dimensional structure, while designers always simplify them as two-dimensional simple structures that are easy to analyze. • Because of the complexity of structural loading on buried structures, simplified methods used in design are sometimes overly conservative. • Therefore, we may have to conduct load tests to have a better understanding of the culvert’s behavior if the simplified models show that the culvert is not safe before we decide for sure that it is the case. Application Education Subunit- Structural Health Monitoring Education Unit

  42. Project #3: Project Goal (2) Application Education Subunit- Structural Health Monitoring Education Unit

  43. Project #3: Project Goal (3) • The culvert in this project is a one-cell reinforced concrete culvert. • Simple calculations show that it is unsafe under typical highway loading. However, visual inspections show that it is performing well and is not exhibiting any signs of distress. • Therefore, you were asked to study its actual behavior by conducting a live load test. Application Education Subunit- Structural Health Monitoring Education Unit

  44. Project #3: Project Goal (4) The goal of the project is to: • Determine the extent of the culvert that is affected by wheel loads by measuring deflections along the culverts length. (Behavior Test) • Estimate the amount of dynamic load amplification caused by trucks traveling at a 50 MPH. (Dynamic Load Allowance (DLA) Tests) Application Education Subunit- Structural Health Monitoring Education Unit

  45. Project #3: Project Goal (5) Culvert Layout Including Ends (Soil Not Shown) Culvert Cross Section Application Education Subunit- Structural Health Monitoring Education Unit

  46. Project #3: Instrumentation Plan Questions (1) Determining Sensor Locations • Box structures are highly statically indeterminate, and their corners barely move. This means that the largest deflections will happen in the middle of the elements forming the box; i.e., walls and slabs. • The member that would experience the largest deflection under a truck load is the one you would measure its response. • You would install sensors along the culvert’s length (perpendicular to the roadway passing over it) to determine the extent affected by the truck load. Application Education Subunit- Structural Health Monitoring Education Unit

  47. Project #3: Instrumentation Plan Questions (2) Sketch on the following figure where you would install the sensors. Application Education Subunit- Structural Health Monitoring Education Unit

  48. Project #3: Instrumentation Plan Questions (5) After you have identified the sensor locations, answer this question. • Recommend the type of sensor that should be used for both goals of the project (extent of load attenuation using deflection measurement and level dynamin load allowance). Bonus Question: • If you were told that pressure sensors can directly measure changes in soil pressure on the top slab of the existing culvert, would you install them instead of putting the sensors inside the culvert? Application Education Subunit- Structural Health Monitoring Education Unit

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