33 



BEAMS. 



Rectangular beams fall by cracking on the tension side, 

 the diagonal tensile stresses being more marked near 

 supports. The neutral axis rising changes the original 

 compresslve stresses to tensile and finally a flaking of the 

 upper portion of the beam takes place. Shearing stresses^ 

 will, however, sometimes cause the cracks to have an 

 inclination from the supports to the center of the beam. 

 The proper placing of U's to take the shearing stresses 

 not taken by bent bars and concrete will prevent this. 



In T beams 



V r =c,t>[h-a} 

 Af r ~ = Moment of Resistance 

 V r ~= Resistance to Shear 



For discussion of beams see Buel & Hill, Taylor & 

 Thompson, and Marsh. 



FOR REFERENCE. 



Diameter multiplied by 3.1416 equals circumference. 



Circumference multiplied by .3183 equals diameter. 



Radius multiplied by 6.2831 equals circumference. 



Square of the diameter multiplied by .7854 equals area. 



Diameter multiplied by .8862 equals side of equal square. 



Area of a rectangle equals length multiplied by breadth. 



Doubling the diameter of a circle Increases its area 

 four times. 



Side of a square multiplied by 1.128 equals diameter of 

 circle of equal area. 



Surface of a sphere equals square of diameter multiplied 

 by 3.1416. 



Area of a triangle equals base multiplied by one-half 

 the altitude. * 



Area of a sector of a circle equals one-half the length 

 of the arc multiplied by the radius of the circle. 



l ru. ft. of water weighs 62 1-3 Ib. and contains T 1 /^ gals. 



1 Kal. of svat.-r ( 1*. S. Si:iinl;mh Wfi.-lis X l-.'J Ib. 



To lind the capacity (U. S. gallons) of cylindrical tanks, 

 square the diameter expressed in Inches, multiply by the 

 length and by .0034. 



The pressure of still water In Ib. per sq. In. against the 

 sides of any pipe, channel or vessel of any shape whatever 

 Is due solely to the "head" or height of the level surface 

 of the water above the point at which the pressure is 

 considered, and is equal to .43302 Ib. per sq. in. or 62.355 

 Ib. per sq. ft. for every foot of head. 



