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1、Chapter 1 Tension,Compression and Shear Mechanics of Materials1.8 Design for Axial Loads and Direct ShearThe determination of stresses,strains,deformations,and allowable loads of simple structures is termed as analysis.Analysis and designIn mechanics of materials,analysis consists of determining the
2、 response of a structure to loads,temperature changes,and other physical actions.A structure is said to be known when there is a complete physical description of the structure,i.e.,all of its properties are known.The determination of the properties of the structure in order that the structure will s
3、upport the loads is called design.Applying to any structure in which the stresses are uniformly distributed over the area.For simple tension and compression members and pins or bolts loaded in shearAnalysis and designThe design of a structure involves strength,stiffness and stability.Stiffness is th
4、e ability of the structure to resist deformation.Stability is the ability of the structure to resist buckling under compression.Optimization is the task of designing the best structure to meet a particular goal,such as minimum weight.Loads are active forces that are applied to the structure by some
5、external cause,such as gravity,water pressure,wind,and earthquake ground motion.Reactions are passive forces that are induced at the supports of the structuretheir magnitudes and directions are determined by the nature of the structure itself.Example(a)Find cable force T and pin support reactions at
6、 O and D.(b)Find the required cross-sectional area of cable ADB if the allowable normal stress is 125 MPa.(c)Determine the required diameter of the pins at O,A,B,and D if the allowable stress in shear is 80 MPa.The pins at O,A,B,and D are in double shear.Also,consider only load P and the weight W of the canopy;disregard the weight of cable ADB.Cable force T:Reaction force at O:Reaction force at D:End