The SCI 301 Puzzler

You are building a porch. You do not have the standard 2 by 6's used for the floor joists, but you have plenty of 2 by 4's. You decide to use two 2 by 4's together in place of one 2 by 6. But there are several ways of doing this.

The 2 by 4's are set side by side, not nailed together. The 2 by 4's are set side by side, nailed together. The 2 by 4's are set on top of each other, not nailed together. The 2 by 4's are set on top of each other, nailed together.

For simplicity, assume the 2 by 4's are all identical and are exactly 2" by 4".

• Which schemes will provide the greatest structural strength against flexure?
• Which schemes will provide the least?

The beam flex equation we used in the lab will provide part of the answer. Be sure to defend your choices.

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