Here are the **top 50** commonly asked questions in **Structural Analysis** interviews. Whether you’re just starting your preparation or need a quick refresher, these questions and answers will help you tackle your interview with confidence.

## Basic Structural Analysis Interview Questions with Answers

### 1. What is Structural Analysis?

Structural Analysis is a branch of engineering that is used to calculate force in members of a structure (frame, truss etc.) in order to design structure to withstand the loads.

### 2. Which type of beams are studied in Structural Analysis?

Indeterminate beams are studied in Structural Analysis. Additional compatibility conditions are required to find support reactions.

### 3. Which type of frames are studied in Structural Analysis?

Determinate frames and indeterminate frames are studied in Structural Analysis. Determinate frames can be analyzed using only equilibrium equations but for indeterminate frames additional compatibility conditions required for analysis.

### 4. Which type of trusses are studied in Structural Analysis?

Determinate and indeterminate trusses which are axially extensible are studied in Structural Analysis.

### 5. What are the most common structures studied in Structural Analysis?

Beams, trusses, frames and arches are the most common structures analyzed in Structural Analysis.

### 6. What are the most common supports used in Structural Analysis?

Roller, hinged or pinned, fixed, inclined roller, guided roller are the most common supports used in Structural Analysis in order to provide stability to the structure.

### 7. What is a rigid joint in terms of Structural Analysis?

Rigid joint is a joint where angle between the connected members at the joint remains same before and after application of load on the structure.

### 8. What is a hinge joint in terms of Structural Analysis?

Hinge joint is a joint where angle between the connected members at the joint may or may not be same before and after application of load on the structure.

### 9. What is difference between Structural Analysis and Strength of Materials?

Mostly determinate beams are analyzed and stresses are calculated in Strength of Materials whereas in Structural Analysis both determinate and indeterminate structures are analyzed.

### 10. What are the most common methods used in Structural Analysis for analysis of indeterminate structures?

Method of consistent deformation, Slope-deflection method, Moment distribution method, stiffness matrix method are generally used when degree of kinematic indeterminacy is less than degree of static indeterminacy.

### 11. What is the use of Structural Analysis?

Structural Analysis is used to design the structures by analyzing them. It is mainly used to design the efficient, stable and economic structures.

### 12. What is the difference between Structural Analysis and Structural Design?

Structural Analysis is used to determine force in the members of a structure whereas Structural Design is used to select dimensions and inertia of member based on the force in the member.

### 13. What are types of Structural Analysis?

Structures can be analyzed using conventional hand calculation methods, finite element analysis, and software like Autodesk Revit, Computers and Structures etc.

### 14. What is an indeterminate structure in Structural Analysis?

A structure with degree of static indeterminacy greater than or equal to one is known as indeterminate structure e.g., propped cantilever beam.

### 15. What is the difference between beam and column in Structural Analysis?

Any member subjected to transverse load can be referred as beam. Beam is a horizontal member whereas column is a vertical member.

### 16. Why the external load is kept at joints of truss in Structural Analysis?

Load can be applied only at the truss joints; otherwise, members will bend due to which bending moment will generate in a truss. Due to occurrence of bending moment, members bend and truss become frame.

### 17. What are the limitations of conventional hand calculation analysis in Structural Analysis?

Hand calculation analysis takes lot of time to analyze indeterminates structures of high degree of static and kinematic indeterminacy. There are also high chances of error occurring while solving calculations.

### 18. What is degree of kinematic indeterminacy in Structural Analysis?

Total number of independent displacements i.e., slope and deflection at all the joints of a structure is known as degree of kinematic of a structure.

### 19. What are frame structures in Structural Analysis?

Frame is a structure made from combination of beams, columns, joints, and supports. Sometimes releases are also used in frames in order to allow all certain displacements. There are two types of frames: sway and non-sway.

### 20. What are truss structures in Structural Analysis?

Truss is a structure in which all the members are connected by smooth pins at their ends, perfectly straight and carry only axial force.

## Intermediate Structural Analysis Interview Questions with Answers

### 21. What is strain energy?

When load is applied gradually on a deformable body, then all the external work done is stored in the deformable body in the form of internal energy. The stored internal energy is known as strain energy.

### 22. What is Castigliano’s theorem for deflection?

Castigliano’s theorem for deflection states that “Deflection at a point is equal to partial derivative of strain energy with respect to concentrated point load acting at that point”.

### 23. What is Castigliano’s theorem for slope?

Castigliano’s theorem for slope states that “Slope at any point is equal to partial derivative of strain energy with respect to concentrated moment acting at that point”.

### 24. What is influence line diagram (ILD)?

The graphical representation of variation of support reaction, shear force at a section, bending moment at a section when unit load moves from one point to another is known as influence line diagram.

### 25. What is Muller Breslau Principle to draw ILD for support reaction?

Muller Breslau states that “To draw the ILD for support reaction at simple support, remove that support without removing any other support and give unit displacement. The deflected shape is itself the ILD for support reaction”.

### 26. What is Muller Breslau Principle to draw ILD for shear force at a section?

Muller Breslau states that “To draw the ILD for shear force at a section, cut the section without removing any support such that the slope at the adjacent supports is equal to 1/L and total ordinate at the section is equal to 1”.

### 27. What is Muller Breslau Principle to draw ILD for bending moment at a section?

Muller Breslau states that “To draw the ILD for bending moment at a section, consider the section as hinge and without removing any support lift the section by ab/L such that sum of slope at adjacent supports is equal to 1”.

### 28. What is Varigron’s theorem?

Varigron’s theorem states that “Moment of the resultant force at a point is equal to summation of moment of the individual forces at the same point”.

### 29. What is carry over moment?

The moment developed at the far end due to the moment applied at the near end of the structure in order to restrict the rotation at far end (fixed support, guided roller) is known as carry over moment.

### 30. What is distribution factor?

Distribution factor is the ratio in which moment applied at rigid joint gets transferred to the different members meeting at the rigid joint.

### 31. What is fixed end moment?

The moment developed at the fixed end of the fixed beam due to the application of load on the span of the fixed beam is known as fixed end moment.

### 32. What is bending moment?

Bending moment is an internal resistance develops due to transverse loading on a member. Bending moment at any section is the summation of all the moments caused due to transverse forces and moments.

### 33. What are the assumptions made in portal method?

There are two assumptions of portal method: i) Point of contraflexure lies at the mid of beams and columns; ii) Horizontal shear in the interior column is twice that of exterior column.

### 34. What are the assumptions made in cantilever method?

There are two assumptions of cantilever method: i) Point of contraflexure lies at the mid of beams and columns; ii) Axial stress in the column is proportional to its distance from the centroid of column group.

### 35. Why slope-deflection method is also known as equilibrium method?

In slope-deflection method, displacements are unknowns and displacements are found using the equilibrium equation; therefore, it is also referred as equilibrium method.

### 36. What are the properties of stiffness matrix?

Stiffness matrix is a square symmetric matrix and all the diagonal elements are always positive. It can’t be written for unstable structures.

### 37. What is method of joints?

Method of joints is used for the analysis of trusses. Equilibrium of a joint is taken under consideration while using this method. It is generally used when force in each member of the truss need to be calculated.

### 38. What is method of sections?

Method of sections is used for the analysis of trusses. Equilibrium of a section is taken under consideration while using this method. The biggest advantage of this method is that the force on any member can be found using an equilibrium equation.

### 39. How couple is balanced in a structure?

Couple can be balanced either in the form of opposite couple or concentrated moment. Concentrated moment is applied only at rigid joint and fixed support.

### 40. What is a link?

Link is a member connected by smooth pins at both the ends and not subjected to any transverse load along the length. It is a member that can carry only axial loading.

### 41. What are the assumptions of elastic-beam theory?

Assumptions of elastic-beam theory: i) There exists a neutral axis, which undergoes zero normal strain upon bending. ii) Upon bending, cross sections remain plan although the angle between them changes.

### 42. What are the caveats of double integration method?

Caveats of double integration method: i) Elastic deflections only; ii) Slope should be small; iii) Deflections due to bending only not due to shear and axial force.

### 43. What is moment-area theorem for slope?

Moment-area theorem for slope states that “The change in slope between any two points on the elastic curve equals the area of the M/EI diagram between these two points”.

### 44. What is geometrically instable structure?

If a structure is subjected to general loading and minimum number of reactions are equal to three and all the reactions are either parallel or concurrent, then the structure is called as geometrically instable.

### 45. What are the assumptions made in unit-load method?

Assumptions made in unit-load method: i) All supports are rigid; ii) Equilibrium of external and internal forces; iii) All strains are within the elastic limit.

### 46. What is superposition principle?

Superposition principle states that “If load is within proportional limit and stress function varies linear with the applied load, then the effect of multiple loading at a point is same as summation of effect of individual loading at the same point”.

### 47. Where to find critical points?

Critical points are present at: i) Start and end of the beam, UDL, and UVL; ii) Points where concentrated load or moment is acting; iii) Points where load intensity or shear force changes its sign.

### 48. What is rotational stiffness?

The moment required to produce unit rotation is known as rotational stiffness. It is expressed by the equation, S=M/θ where S is rotational stiffness, M is equal to the applied moment and θ is rotation at the point of application of moment.

### 49. What is shear force?

Shear force is an internal resistance develops due to transverse loading on a member. Shear force at any section is the summation of all the transverse force while moving from left to right or vice-versa.

### 50. What is difference between sagging and hogging bending moment?

In sagging bending moment, fiber above neutral axis is subjected to compression and fiber below neutral axis is subjected to tension whereas in hogging bending moment, fiber above and below neutral axis is subjected to tension and compression respectively.

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