Computation of Principal Stress 



39. The measured moments and axial load can be combined into a single 

 uniaxial stress component using a combined biaxial bending and axial formula 



= *ty + M^x + p 



(2) 



where 



Rjj , My = moment about the x and y axes , respectively 



x, y = distance along the x and y axes, respectively, from the 

 neutral surface to the point of measurement 



I x , I y = moments of inertia 

 P = axial load 

 A = cross-sectional area 

 Note that in Figure 8 the moments K^ and My are also designated M h and 

 M v , respectively. The h and v subscripts refer to horizontal and verti- 

 cal moments and have been used in several Crescent City dolos references. 



X 



M = M h \ 



HORIZONTAL 

 FLUKE 



Figure 7. Definition sketch for principal stress computation 

 40. The maximum bending stress for the cross section can be found 

 using an iterative technique by sampling the stress around the cross-section 

 perimeter. In the prototype, axial strains were measured by summing rather 

 than differencing the opposing strain gage bridges, but shearing strains due 

 to flexure were not measured. 



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