UTPA STEM/CBI Courses/Statics/Truss Bridge

Course Title: Introduction to Mechanical Engineering

Lecture Topic: Statics / Truss Bridge

Instructor: Drs. Arturo A. Fuentes and Horacio Vazquez

Institution: UTPA

Backwards Design

Course Objectives

• Primary Objectives- By the next class period students will be able to:
  • Explain some aspects of the engineering design process
  • Understand and explain the concept of tension/compression
  • Understand the design of a truss bridge
  • Design and construct prototypes
  • Function in diverse teams
  • Document results and conclusions

• Sub Objectives- The objectives will require that students be able to:
  • Understand brainstorm process
  • Understand and use basic engineering instrumentation and software
  • Understand and use engineering data presentation tools (graphs and tables)
  • Understand and use dimensions and units
  • Perform unit conversions

• Difficulties- Students may have difficulty:
  • Understanding the concepts of tension and compression. They usually benefit from reviewing and practicing concepts related to the engineering design process and teamwork skills in a real engineering context.

• Real-World Contexts- There are many ways that students can use this material in the real-world, such as:
  • Introducing mechanics fundamentals to students early on in their careers allows them to connect their current knowledge to engineering applications. The mechanics knowledge gained provides a foundation and motivation to many courses in the mechanical, civil, and industrial engineering curriculum.

Model of Knowledge

• Concept Map
  • Engineering Design Process
    • Role of Prototype/model testing and validation
  • Truss Bridge
    • Tension
    • Compression
  • Prototype Construction and Instrumentation
  • Teamwork Skills
    • Brainstorm skills
  • Engineering Documentation

• Content Priorities
  • Enduring Understanding
    • Tension and Compression concepts, units, dimensions, unit conversion
  • Important to Do and Know
    • Teamwork Skills
  • Worth Being Familiar with
    • Software and instrumentation

Assessment of Learning

• Formative Assessment
  • In Class (groups)
    • Worksheet
  • Homework (individual)
    • Report
    • Quiz
• Summative Assessment
  • Exam

Legacy Cycle

OBJECTIVE

By the next class period, students will be able to:

• Calculate tension or compression in different truss members
• Design and construct a prototype truss bridge

The objectives will require that students be able to:

• Brainstorm multiple truss bridge designs
• Evaluate the bridge designs in order to determine the best design

THE CHALLENGE

Your company’s bridge has failed and it is your job as the new design engineer to determine what could have caused the failure of the bridge and, as much as possible, defend the company.

GENERATE IDEAS

Your supervisor tells you that he will meet with you shortly to hear your initial thoughts, to share some information that might be useful, and to answer any questions that you might have. The information that you will provide will be used as testimony by the company in a court of law. Students will begin to brainstorm alone for a period of 5 minutes. They will then continue brainstorming with each other and share ideas for the next 10 minutes. [Ideally, groups will be of size 4 and different group members will be in charge of certain aspects of keeping the group in order]

MULTIPLE PERSPECTIVES

Different cases scenarios including overload, accidents, natural disasters, design errors, manufacturing errors, material quality issues, etc. Instructors will inform the students that during that day a truck skipped the weight station checkpoint. Also they will receive information about the maximum load permissible on the bridge members. Experts will also begin to present ideas behind models and their importance in real life applications.

RESEARCH & REVISE

The instructor will show a truss bridge presentation. The instructor will then show a presentation covering tension vs. compression in structural elements. A lecture over tension/compression will be presented which will include the effects of weight (force) on the member’s behavior. Having this information at hand the students will be supplied with Pasco equipment. Related to this topic, they will be free to use the equipment as they see fit. An illustration showing their bridge before failure will be provided to them.

TEST YOUR METTLE

Determine how much load (and type of load: tension or compression) is transferred to each member of the truss bridge structure when loads are placed at key points in the structure. A handout which asks the students to identify if a member is in compression or tension will be provided. Students will be asked to work on the handout individually and turn in at the end of 10 minutes or the professor's allotted time.

GO PUBLIC

Online Report:

Students will share their findings and possible challenge solution with the other group. Having shared what they thought could have caused the bridge to fail, they will return to their formal groups to finalize their solution, and turn it in to the instructor.