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Building a Bridge with Middle Schoolers

Markus Wernli explains bridge beam deflection design to students at Washington Middle School.

BergerABAM was proud to support the third annual SAME STEM Fair at Washington Middle School in Seattle, Washington, on 10 February 2017. Washington Middle School hosts the annual event to expose students to the engineering industry through presentations and hands-on learning activities.

The Society of American Military Engineers (SAME) Seattle Post sponsors the event to promote outreach and mentorships and inspire students to pursue careers in science, technology, engineering, and math (STEM) fields. Volunteer professional engineers and scientists are invited to host booths at the event and provide presentations and hands-on integrated learning activities that educate middle schoolers about careers in science-related fields.

Six 50-minute sessions were held throughout the day, allowing groups of students to explore various booths in the school gymnasium. Presenters talked about their interests and aptitudes that led them to their chosen field, including education, networking opportunities, and career advancement. Many used visual aids, such as models, field equipment, and mechanical items to demonstrate various projects and fields of study.

Engineers Markus Wernli and Ryan Bell, both from BergerABAM’s Waterfront Department, hosted a table and provided a simple demonstration on bridge beam deflection design and construction. For their demonstration, they used six plywood beams that were each 1.5 inches wide by 0.25 inch thick. First, they placed one plank on two end supports and loaded it up with a 5-pound weight to show how the “bridge” deflected significantly under the weight. Then, they stacked two more beams on top of the plank and added the same weighted load to show how the beam deflected roughly one-third of the original amount.

For comparison, the additional three beams had been glued together with the center plank turned on its long side to form an I-beam. By replacing the stacked plank with the I-beam on the two end supports, Markus and Ryan showed how three planks of the same size and material became roughly 280 times stronger after simply changing the configuration of the cross section. They continued to add 35, 45, 50, and 100 pounds onto the I-beam, proving that the beam had minimal deflection that was almost indistinguishable to the eye.

The Seattle SAME STEM Committee is a non-profit group that advocates outreach with educators and K-12 students to promote STEM careers through mentoring.