STRUCTURAL REINFORCEMENT            Name: ________________ E.N.____

                                                                                    Period: ____________ Date: ______

 

RATIONALE

Students will learn how diagonal braces, shear walls, and rigid connections strengthen a structure to carry forces resulting from earthquake shaking.

 

FOCUS QUESTIONS

How may the structure of a building be reinforced to make it better able to withstand earthquake shaking?

 

OBJECTIVES

Students will:

1. Recognize some of the structural elements of a building.

2. Describe how the horizontal and vertical structural elements carry the horizontal and vertical loads of a building.

3. Describe how diagonal braces, shear walls, and rigid connections provide paths for the horizontal load resulting

from an earthquake.

4. Observe how added structural elements strengthen a model wall to withstand shaking.

 

Introduction

You will demonstrate how the structural elements of a wall carry forces using three structural elements that carry the lateral shear forces caused by ground shaking during an earthquake:

1.      diagonal bracing,

2.      shear walls

3.      rigid connections.

 

1. Q: “What holds this wall up?”  (Note: What you refer to as weight will be called the force of gravity in this lesson.)

 

2. Q: Predict what would happen if you quickly pushed the base of the wall, simulating an earthquake. Remember

that an earthquake may cause ground shaking in many directions, but for now we are modeling shaking in one direction only.

 

 

3. In your SET groups start your investigation.

 

a. One student will push at the bottom of the model from the lower right or left side.

Q: Why didn’t the other floors collapse?

 

Load diagram

 

 

 

 

b. carefully apply horizontal forces at different points on the model to simulate earthquake shaking. (Earthquakes affect buildings at ground level.)

 

4. Q: How could you add structural elements to create a path for the load to follow to the ground when strong forces act upon the structure? On each of the three diagrams provided, draw a force arrow (a vector) and trace the path the force takes to the ground.

 

5. Design and build three different arrangements of the six structural elements depicted on the worksheet. Each time you modify the design you must modify the diagram to show the new load path.  When a structure is well reinforced, you should be able to push on the upper story and slide the whole structure without any of the walls failing.

 

6. Remove an element (a craft stick) that, according to the load path diagram, is not carrying any load. Unbolt one end of that element and push the reinforced structure to see if it holds. It will, if the load path is correct. Q: where you right?

 

 

7.  Answer post lab questions.