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5.6.3 Two-Story, Four-Bay Semirigid Frame

Figure 5.44 shows a two-story, four-bay semirigid frame. The height of each story is 12 ft and it is 25 ft wide. The spacing of the frames is 25 ft. The frame is subjected to a distributed gravity and concentrated lateral loads. The roof beams connections are the top and seat L6 x 4.0 x 3/8 x 7 angle with double web angles of L4 x 3.5 x 1/4 x 5.5 made of A36 steel. The floor beam connections are the top and seat angles of L6 x 4 x 9/16 x 7 with double web angles of L4 x 3.5 x 5/16 x 8.5. All fasteners are A325 |in.-diameter bolts. All members are assumed to be continuously braced laterally.

5.6.3.1 Design by Advanced Analysis

Step 1: Load condition and preliminary member size. The load conditions are shown in Figure 5.44. The initial member sizes are selected as W8 x 21, W12 x 22, and W16 x 40 for the columns, the roof beams, and the floor beams, respectively.

TABLE 5.9 Input Data, P.DAT, of the Explicit Imperfection Modeling for the Unbraced Eight-Story Frame: (a) Explicit Imperfection Modeling and (b) Further Reduced Tangent Modulus

(a) Unbraced eight-story frame, explicit imperfection modeling

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