1 IT3Civ4 T61 P3 In class we have learned that the full bear

1. IT3_Civ.4, T6.1, P3] In class, we have learned that the full bearing strength is the upper limit of the bearing strength, expressed as OR,-(2.4 tdFu)--AISC Eq (J3- 6a) on page 16.1-127. A value s ful is defined as the spacing s at which the full bearing strength is achieved. Similarly, Le full is defined as the edge distance at which the full bearing strength is achieved. The bearing strength is directly related to the \"clear distance\"L in between holes and edges. With the relationship shown in the figure below, on le, Le and s, please complete the following problems: a. Please derive the formulas to calculate sfull and Le ful, in terms of bolt diameter d; Hint: Find out when le is equal to what value, can the full bearing strength be achieved? And then write out the formula for sfull and Le full- b. Please compare the sfull and Le full values calculated using the formulas obtained in a) with the tabulated values (for cases d = 5/8 in., 3/4 in. 7/8 in, and 1 in. standard hole only) in Table 7-4 and Table 7-5 in AISCM pages 7-26 and 7-28. Are they the same or close to cach other? What are your findings? O\' O

Solution

a) There is a discontinuity in the bearing strength limit state when end distance equals 1.5 times bolt diameter. LRFD states that for connections with two or more bolts in the line of force, once the distance from the end of the connected part to the center of a standard hole reaches 1.5 times the bolt diameter and the spacing is 3 times bolt diameter, the designer may use the full bearing strength (2.4 db.t.Fu) of the plate for all holes.

b) d= 5/8 = 0.625 , spacing = 3*0.625= 1.875, Le = 1.5*0.625= 0.937

From table values, Minimum Le =0.875 which is not the same

For d = 3/4, spacing = 2.25, Le = 1.125

Table value Le = 1 (not same)

For d = 7/8, spacing = 2.625, Le = 1.31

Table value = Le = 1.125 (not same)

For d= 1, spacing = 3, Le = 1.5

Table value Le = 1.25 (not same)