When an earthquake occurs, the damage to buildings and other structures can be devastating. Multiple factors determine whether or not a building survives an earthquake intact, according to Multidisciplinary Center for Earthquake Engineering Research Center at the University at Buffalo. These include the building's shape, height and construction materials, as well as the type of soil on which the building stands. Students and teachers can use a variety of experiments and science projects to explore the effects an earthquake might have on different types of structures.
In order to test different structures' resilience in an earthquake, students first need a way to duplicate the structural stress caused by intense vibrations. Although one option is to simply shake the base upon which a model building rests, devices such as earthquake generators provide a more consistent shaking motion. Seventh-grader Devon Thomson designed an earthquake machine using plywood, wire, bamboo sticks, compression springs, duct tape and screw eyes, as well as access to a few basic tools such as a circular saw, carpenter's stapler and staples, pliers and cutting shears. Detailed instructions for Thomson's machine may be found on the Online Digital Education Connection website.
Another option for reproducing the effects of an earthquake can be found on the website of Discovery Education. To build this simple generator, students use easily obtainable supplies such as varying lengths of PVC pipe, plywood, eye bolts, dowels or pencils and a rubber band. Completion of the project requires some drilling. Teachers with the budget to do so can purchase a ready-made earthquake generator from Kelvin Educational.
Wood Frame Structures
The Multidisciplinary Center for Earthquake Engineering Research Center website provides directions for constructing a model replicating a wood frame house or building. Students build the two-story frame using ice cream sticks joined together with clay. Mount the building on a piece of styrofoam with a portion cut away to serve as the basement. Once the class tests the strength of the structure by using a tabletop earthquake generator, they may experiment with strengthening it by adding a variety of additional materials such as straws and kite strings, or by using more ice cream sticks. Model house kits made from balsa wood provide another option for testing the strength of wood frame buildings in an earthquake. Available kits include Kelvin Education's A-frame and one-story structures, and two-story town house and truss roof kits available from AC Supply.
Many homes and buildings are constructed using masonry materials such as brick. Students can compare the relative strength of wood frame and masonry construction by using a model made from sugar cubes, peanut butter and frosting or double-sided tape, cardboard and styrofoam. Once the basic structure has been tested using an earthquake generator, students can experiment with strengthening their model using pieces of aluminium window screening cut to fit the inside walls. Details for constructing this model are found on the Multidisciplinary Center for Earthquake Engineering Research Center website.
Houses and other buildings are not the only structures subject to earthquake damage and destruction. In addition to load-bearing capacity, resilience and strength in the face of an earthquake's vibrations are other important considerations in engineering a safe bridge. Teachers can guide students in learning about different bridge designs, and then let the students construct arch, suspension and beam bridges to test using an earthquake generator. Discovery Education's website suggests using models built from drinking straws cut into different lengths and masking tape. Teachers might also consider purchasing balsa wood bridge kits, available in student packs and team packs from Kelvin Educational.