1 STRUCTURAL ANALYSIS TWO MARKS BCECCE502R02 / MSTCCE502R01/MCMCCE502R01 1. Degree of indeterminacy? The excess of number of reactions that make a structure indeterminate is called degree of indeterminacy. Degree of indeterminacy=no of unknowns – no of independent static equilibrium 2. Degree of freedom? Degree of freedom is defined as the least no of independent displacement required to define the deformed shape of a structure (or) no of unknown displacements of joints. 3. Types of degree of freedom? (i) Nodal type (ii) Joint type 4. What is crown in an arch? The topmost point in an arch is called crown. 5. Types of arches based on hinges? (i) Circular arch (ii) Parabolic arch 6. State Eddy’s theorem? The bending moment at any section of an arch is equal to the vertical intercept between the linear arch and center line of actual arch. 7) What is an arch? Arches are shaped to take the load above them and develop only compression. 8) what is a catenary? Catenary is the shape taken up by a cable (or) rope freely suspended between two supports and under its own self weight. 2 9) Define kinematic indeterminancy? Kinematic indeterminancy is defined as the least no of independent displacements required to define the deformed shape of structure. 10) Define rise of an arch? When two hinges of the arch are at same level.The height of crown above the level of the lower hinges are called rise of an arch. 11) Define horizontal thrust? The horizontal component of the reaction of either lower and is called horizontal thrust. 12) Define beam moment in an arch? The beam moment at any section in an arch is bending moment at the section considering the span as that of simply supported beams. 13) Write the formula for calculatin the normal that and radial shearin an arch? Normal thrust=N=Vsinθ+Hcosθ. Radial Shear=Q=Vcosθ-Hsinθ. 14) Define Static indeterminency? A structure is said to be statically indeterminate if it cannot be analyazed from the principles of static alone. 15) Define influence line? A curve or graph that represents a function like a reaction at a support the shear force at a section.The bonding moment at a section of a structure for various positions of a unit load on the span of the structure is called influence diagram. 16) Uses of influence line? i) To determine the value of quantity for a given system of loads on the span of a structure. ii) To determine the position of a liveload for the quantity to have the maximum value of quantity. 3 17) Define sway? Sway is defined as joint moment of a portal frame due to load acting unit. 18) What are the causes of sidesway? i) Eccentric (or) unsymmentrical loading on the portal frame. ii) Unsymmetrical outline of portal frame. 19) Define distribution factor? Distribution factor for a member at a joint is the ratio of the stiffness of the member to the total stiffness of all the members meeting at a joint. Distribution factor = Stiffness of a member / Total stiffness of all member meeting at joint. 20) Define stiffness? Stiffness of a member is the moment require to rotate the end under consistent through unit angle. 21) Define pure sway frame? A pure sway frame is a type of sway type portal frame in which the loading on the portal frame consists of a horizontal load say p at the level of the beam. 22) What is carry over factor? When a moment m is applied in one joint of a beam which introduces moment on the other end fixed is called carry over moment. 23) What is the main differnce between moment distribution method and kanis method? Quanties iterated in the moment distribution method are the moments to the member end moments instead of end moment themselves. 24) Castiglianos first theorem ? In a linearly elastic structure portal derivative of strain energy with respect to a load is equal to deflection of the point where the load is acting.The deflection being measure in dircetion of load dv/dpi = Δi dv/dms=Qj 4 25) What is suspension bridges? Suspension bridges are used for roadways for spans more than 200m and light traffic ways of span more than 300m. A suspension bridge is a bridge consisting of two cables with number of suspenders (hangers) supporting the roadway. 26) Define strain energy? The internal energy stored within the body equal to amount of workdone on it by the applied force is known as strain energy. 27) Castiglianos second theorem? In a linearly elastic structure partial derivative of strain energy with respective deflection is equal to load applied at the joint. 28) Define primary structure? A structure formed by the removing the excess are reduntant restrains from a indeterminate structure making it staticallly determinant is called primary structure. 29) What are the condition of equilibrium? Three conditions of equilibrium are the sum of horizontal forces,vertical forces and moment at any joint should be equal to zero. H = 0 ; V=0 ; M=0 ; 30) Define virtual work? Work done by a real force due to virtual displacement is called virtual work. 31) Maxwell’s reciprocal theorem? Displacement of point A due to load at point B is same as diplacement of point B same load acting at a point A.The displacement being measured in the direction of load. 32) What are the assumptions made in slope deflection method? i) Joints of the frame or rigid. ii) Distoring due to axial and shear stress being very small are neglected. 5 33) What are the forces available at the point of maximum dip in a cable? For a cable subjected to saddle over the whole structure the available forces at the dip are Horizontal force, H = wl2/ 8h, Vertical force V=0. 34)What are the two basic methods available for analyzing the statically indeterminate structure? 1)Slope deflection method 2)Moment distribution method 3)Kanis method 35)Why is slope deflection method is called displacement method? Stiffness method is based on the superposition of displacements and hence is also known as the displacement method. 36) Write diffrence between circular arch and parabolic arch? In circular arch radius is required. In parabolic arch radius is not required. 37) Is it possible to develop the flexibility matrix for an unstable structure? In order to develop the flexibility matrix for a structure, it has to be stable and determinate. 38) What is the relation between flexibility and stiffness matrix? The element stiffness matrix ‘k’ is the inverse of the element flexibility matrix ‘f’ and is given by f = 1/k or k = 1/f. 39) What are the types of structures that can be solved using stiffness matrix method? Structures such as simply supported, fixed beams and portal frames can be solved using stiffness matrix method. 40) What are the basic unknowns in stiffness matrix method? In the stiffness matrix method nodal displacements are treated as the basic unknowns for the solution of indeterminate structures. 41) Define stiffness coefficient kij.? Stiffness coefficient ‘kij’ is defined as the force developed at joint ‘i’ due to unit displacement at joint ‘j’ while all other joints are fixed. 42) What is the basic aim of the stiffness method? The aim of the stiffness method is to evaluate the values of generalized coordinates ‘r’ knowing the structure stiffness matrix ‘k’ and nodal loads ‘R’ through the structure equilibrium equation. 6 {R} = [K] {r} 43) How are the basic equations of stiffness matrix obtained? 1)Compatibility of displacements 2)Force displacement relationships 44) What is the equilibrium condition used in the stiffness method? The external loads and the internal member forces must be in equilibrium at the nodal points. 45) What is the compatibility condition used in the flexibility method? The deformed elements fit together at nodal points. 46)What are the uses of rolling loads? Rolling loads are the loads which are useful in this structure which is having a possibility of vehicular movement . Example bridge decks. 47) What is the condition for absolute maximum bending moment when a pair of loads moves over a girder? The absolute maximum bending moment occurs when the c.g of the span is placed midway between the c.g of the loading system and the heavier load. 48) Statically determinate structure and statically indeterminate structure? Statically determinate statically indeterminate No stresses are caused due to temperature Stresses are caused due to temperature changes variations No stresses are caused due to lack of fit Stresses are caused due to lack of fit Conditions of equilibrium are sufficient to fully Conditions of equilibrium are insufficient to analyse the structure fully analyse the structure 49) Define critical section? Critical section may be defined as the section , which is getting the maximum values of shear force or bending moment for a set of loading system. 50) What are the different types of trusses available? a) Deck type truss b) Through type truss 7 51) DEGREE OF REDUNDANCY? A frame is said to be statically indeterminate when the number of unknowns reaction or stress exceed thye total number of condition equation of equilibrium. E = R - 52) What is the nature of force in the cables? Cables of cable structures have only tension and no compression or bending. 53) Explain the two ways by which a cable can be anchored or supported? Cables can be supported by providing guyed pulley support and by providing roller support. 54) Mention the different types of cable structures? Cable structures are mainly of two types: (a) Cable over a guide pulley (b) Cable over a saddle 55) What is need for providing anchor cables in towers? Anchor cables are provided in towers to reduce the bending moment.