Reinforced & Prestressed Concrete for Construction Managers

This brief quiz will test you on how much you already know about reinforcing and prestressing, and will set the stage for some of the things we will discuss in the following lectures.

In this section we will introduce the concepts that will be covered in this course. The idea is to get you thinking about the concepts and the learning objectives. Also included are the first handouts that are included with this course. Make sure to check them out and get them downloaded! This supplemental material makes a great set of resources to take away from this class. Access it by clicking on the RESOURCES tab at the top of each lecture.

Learning objectives are concise, measurable outcomes. These are the things you should be able to do after completing this course:

• Explain the meaning of passive reinforcing versus active reinforcing
• List examples of active and passive reinforcing
• Discuss the effects of adding rebar to concrete
• Explain how the change in location of the rebar within the concrete effects its performance
• List advantages of prestressed concrete
• Describe the difference between pre-tensioned and post-tensioned reinforcing
• Describe the precast concrete process
• Explain how post-tensioned concrete works
• List common examples of prestressed concrete structures

This lecture contains the vocuabulary refernece material for the course and discusses safety considerations.

Concrete is the most widely used building material on the planet! Learn why here.

This section gives a brief introduction and overview of concrete; what's in it and how it works. This section introduces the chemical reaction known as "hydration" which is the chemical reaction between cement and water that results in the concrete getting hard. We also introduce the concept of using industrial by-products as a partial replacement for cement. Download the PDF file in the Resources tab to learn more about one of the most common by-products used in concrete.

Want a more in depth look at concrete? Check out our course here on Udemy titled "Become a Better Construction Manager - Learn About Concrete".

Concrete is strong in compression and weak in tension. Compression is the force that squeezes something together and tension is the force that pulls it apart.

This section looks at the forces and stresses that cause concrete to crack. Both tension and shear are discussed.

We use different techniques, including control joints and passive reinforcing like rebar and wire mesh to control cracking. These methods will not stop concrete from cracking, but if utilized correctly they will control the cracking, limit the crack widths, and prevent cracking from leading to failure.

This final lecture on passive reinforcing pulls together the concepts learned so far, and explains the reasoning behind the use of the term "passive" reinforcing.

Take this short quiz to see what you have learned so far!

Prestressed concrete is actively reinforced. This means that we are applying forces to the concrete before we place it in service in order to enhance its performance.

Increasing the tensile capacity of the concrete member results in several advantages including longer spans, shallower members and better crack control. All of these things combine to result in economic advantages and savings in concrete.

Be sure to check out the handout material in the Resources tab for a paper published by the Post-Tensioning Institute about the sustainability benefits of prestressed post-tensioned concrete,

Active and Passive reinforcing are often used together to create a concrete structure that is economical and meets the performance requirements.

Today, the use of prestressing is common in concrete structures due to its economic advantages. Hotels, office buildings, bridges, parking structures and even residential foundations are all common uses for prestressed concrete.

The White Paper included in the Resources tab introduces the concept of prestressed concrete to build "high performance" structures.

Layout is determined by the designer, with proper placement being critical to the performance of the structure.

Prestressing steel is tensioned to a very high force (33,000 pounds or more). Safety is extremely important. Personnel who are not a part of the stressing operation should not be permitted in the area. Personel working on the stressing operation need to be properly trained.

Let's see how much you learned about prestressed concrete!

We use some form of passive reinforcing in virtually all types of concrete structures; any time we expect tensile stresses to exceed the strength of the concrete. We add active reinforcing to further enhance the properties and the performance of some concrete structures when we want longer spans, thinner concrete sections and stiffer beams and slabs.

This lecture sumarizes the strenghts of the various materials discussed in this course and wraps up the discussion on the advantages and limitations of prestressed concrete.

Take this final quiz to check your knowledge against the learning objectives listed at the begining of this course.

Thank you for completing this course. You should now have a good understanding of why we reinforce concrete and of the benefits of prestressed concrete. You should understand why a designer might make the decision to utilize prestressed concrete and what the differences are between precast, pre-stressed, concrete and cast-in-place, post-tensioned concrete.

If you enjoyed this course, please consider leaving a positive review! If you have questions, make sure to post them in the discussion board for this course. I check for questions everyday; or you can use the message feature to send me a note or question.

Thanks, and be sure to look for our other courses. Additional topics are added each month.