tailieunhanh - Lecture Strength of Materials I: Chapter 3 - PhD. Tran Minh Tu

Chapter 3 - Axially loaded members. The following will be discussed in this chapter: Normal stress and normal strain, tension and compression test, poisson’s ratio, shearing strain, allowable stress – factor of safety, statically indeterminate problem. | Lecture Strength of Materials I: Chapter 3 - PhD. Tran Minh Tu STRENGTH OF MATERIALS 1/10/2013 TRAN MINH TU - University of Civil Engineering, 1 Giai Phong Str. 55, Hai Ba Trung Dist. Hanoi, Vietnam Axially loaded CHAPTER members 3 1/10/2013 2 Contents . Introduction Stress and Normal Strain . Tension and Compression Test . Poisson’s ratio . Shearing Strain . Allowable Stress – Factor of Safety . Statically Indeterminate Problem 1/10/2013 3 . Introduction • Suitability of a structure or machine may depend on the deformations in the structure as well as the stresses induced under loading. Statics analyses alone are not sufficient. • Considering structures as deformable ones allows us to determinate the member forces and reactions which are statically indeterminate. • Determination of the stress distribution within a member also requires the consideration of deformations in the member. • Chapter 3 is concerned with the stress and deformation of a structural member under axial loading. Later chapters will deal with torsional and pure bending loads. 1/10/2013 4 . Introduction • Prismatic bar: Straight structural member with the same cross- section throughout its length • Axial force: Load directed along the axis of the member • Axial force can be tensile or compressive Axially loaded members are structural components subjected only to axial force (tension or compression) 1/10/2013 5 . Introduction 1/10/2013 6 . Introduction Axial force diagram Using the method of section , the internal axial force is obtained from the equilibrium as a function of coordinate z Z 0 N z . Kinematic assumptions Before deformation After deformation 1/10/2013 7 . Normal stress and normal strain Kinematic assumptions 1. The axis of the member remains straight 2. Cross sections which are plane and are perpendicular to the axis before .