At a Glance: Students design and build a model earthquake-resistant tower from balsa sticks and destructively test it on the EQs Tremor Table.
Concepts:
Students learn about the dynamics of an earthquake and experiment with structural designs that can withstand geophysical forces.
Details: Using their knowledge of wave mechanics and the construction tips in the Earthquake Engineering book, students design an earthquake-resistant tower that simulates a 16-story, 160-foot-tall building that measures 40 feet by 40 feet at the base. Two identical side views of their final design are sketched on 11" x 17" graph paper, which becomes the construction pattern.
The pattern is placed on a piece of foam board and covered with waxed paper. Students measure and cut balsa wood columns for the sides of the tower and pin them to the pattern. Diagonal girders that connect the columns are measured, cut, and glued in place to create two sides of the tower's frame. The two sides are connected using the foundation block and floor plates. Then, diagonal braces are added for the two additional sides of the tower. When the glue is dry, mass plates are fastened on each floor of the tower to approximate the weight (adjusted to scale) of a 16-story building.
Completed towers are attached to the EQs Programmable Tremor Table, an electronic device that subjects student structures to varying magnitudes of both the push-pull (P waves) and side-to-side (S waves) action of an earthquake. Each tower is tested using frequencies and times programmed by the instructor. The tower that withstands the greatest earthquake magnitude wins the competition.
At a Glance: Students design and build a model earthquake-resistant tower from balsa sticks and destructively test it on the EQs Tremor Table. 
