:*s NOTES ON PLATE-CJIRDEB DESIGN 



web cross each other at right angles; at tin- neutral 

 they are approximately equal, ami mak.'- ftDgfa of approx- 

 imately 45 with the axi- and equal the -hearing stre886fl in 

 intensity: above the neutral axis the cnmpiv--i\ v Btrefifl 

 intensity is increasing while the ten-He is decreasing: beln\v 

 the axis tin- opposite relation exists. 



The shearing stresses are of the greatest intensity at 

 the neutral axis, on horizontal and vertical planes, for 

 any cross-section. At the cross-section where the greatest 

 resultant shear occurs, there, on the neutral axis will be 

 found the maximum shearing unit stresses. For simple 

 -pans the shear is a maximum at the ends of the span. 



It is the practice to design web plates SO that they 

 will resist the -hear at the point of maximum -hear, and 

 have enough thickness to provide ample bearing for the 

 rivetfl connecting flange angles to the web: this latter very 

 frequently determines the thickness of the web plate. The 

 n of the web plate is also governed by practical con- 

 siderations, such as requirements for handling in shop and 

 field and requirements to resist corrosion. 



The best practice requires as a minimum for tin thick- 

 ness of girder webs: A" for railway, jf" for highway, 

 and A" for building work. It is the practically univ 



in to make the web plate, for a girder, of uniform 

 on throughout its length. 



The shearing unit stress should be about 20% leflfl 

 than that used for direct ten-ion, that is, where Pi.ooi) 

 is u.-ed for irn-ion, 13,000 is a con-i-tmt unit for the max- 

 imum shearing st res- inten.-ity. Where the ^hearing 

 is assumed to be uniformly distributed over the girder 



