Structural Analysis-I Chapter:3 Fundamentals Mansi Thacker : 120850106042 Kajal thacker : 120850106001 Aman Bhimani : 120850106033 Harpalsinh Jadeha : 120850106017 Faizal brair : 120850106023
Statically Determinate structure The structure for which the reactions at the supports & internal forces in the members can be found out by the conditions of static equilibrium, is called a statically determinate structure. Example of determinate structures are: simply supported beams, cantilever beams, single and double overhanging beams, three hinged arches , etc. There are three basic conditions of static equilibrium: ΣH = 0 ΣV = 0 ΣM = 0
Statically indeterminate structure The structure for which the reactions at the supports & the internal forces in the members can not be found out by the conditions of static equilibrium, is called statically indeterminate structure. Examples of indeterminate structures are: fixed beams, continuous beams, fixed arches, two hinged arches, portals, multistoried frames , etc. If equations of static equilibrium are not sufficient to determine all the unknown reactions (vertical, horizontal & moment reactions) acting on the structure, it is called externally indeterminate structure or externally redundant structure. If equations of static equilibrium are not sufficient to determine all the internal forces and moments in the member of the structure, even though all the external forces acting on the structure are known, is called internally indeterminate structure or internally redundant structure.
DEGREE OF STATIC INDETERMINCY(DS): The degree of static indeterminacy of the structure may be defined as the number of unknown forces in excess of equations of statics. It is also known as degree of redundancy. Therefore, degree of static indeterminacy = Total no. of unknown forces – Number of equations of static available Redundants may be support reactions or internal forces in the members. If redundants are removed from the structure, it becomes determinate. Thus, the degree of indetermincy is equal to the number of releases necessary make the structure determinate. DS = DSE + DSI