160 PRACTICAL STRUCTURAL DESIGN 



The lap will be in the panels in which the stress is 45,000 Ibs. 

 Each outer plank will carry half the stress. We will assume two rows 

 of f-in. bolts fastening the planks together and these bolts will be 

 in double shear, for they pass through the center plank. Referring 

 to the table on page 139 each bolt is capable of carrying 1450 Ibs. 



While each outer planks carries half the stress, when all bolting 

 is done, all the stress passes through the middle splice, half coming 

 in from each side plank and being transferred through the bolts 

 to the plank on the other side; therefore the bolts in the middle 

 splice must be proportioned to carry all the tension. 



45 000 



Number of bolts required = .. * _ =31. Use 32 bolts. 



1450 



Total shearing area = - ' = 375 sq. in. 



Spacing of bolts for shear = -== - - = 0.975 in. 



45,000x0.1 

 Spacing required for transverse tension = -r^ ^ ~ = 0.147 in. 



Adding diameter of bolts = 0.75 



Required spacing of bolts = 1.872 in. 



The spacing may be increased to any desirable amount, so before 

 settling the matter the connections for the other planks will be 

 taken up. 



The other planks each carry one-half the tension, so all the fig- 

 ures above may be prorated accordingly. In each joint there will 



375 



be 16 bolts. The total area required for shear = ^- = 187.5 sq. ins. 



188 

 Spacing of bolts for shear = ^ ^ ~ = 0-98 in. 



22,500x0.1 ni 

 Spacing required for transverse tension = _, fi fi = 0.146 



Adding diameter of bolts = 0.75 



Required spacing for bolts = 1.872 in. 



Before spacing the bolts determine how far the first bolts will 

 be placed from the end of the planks. The shear on one bolt is 

 1450 Ibs. with bearing on a thickness of 6 ins. of plank. For the 

 interior bolts this is placed on two lines at the ends of the diameter, 

 but for an end bolt it is best to use but one line, considering that 

 the greatest danger is shearing on a line through the center 

 of the bolts. The length required for shear on the end bolt 



