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Q3. A wooden beam is fabricated from one 50 x 300 and two 50x250-dimension lumber boards to form the double-tee cross section shown in Figure. The beam flange is fastened to the stem with nails. Each nail can safely transmit a force of 780 N in direct shear. The allowable shear stress of the wood is 480 kPa. a) If the nails are uniformly spaced at an interval of s = 100 mm. along the span, what is the maximum internal shear force V that can be supported by the double-tee cross section? b) What nail spacing s would be necessary to develop the full strength of the double-tee shape in shear? (Full strength means that the maximum horizontal shear stress in the double-tee shape equals the allowable shear stress of the wood.) 300 mm Nails 50 mm 250 mm 50 mm 50 mm