CTEVT | Mechanics Of Structure | Diploma in engineering | Question paper/diploma in civil engineering
Mechanics Of Structure Question paper-2077
Mechanics Of Structure Question paper-2079/80
Solution:
1. a) Stress-Strain Diagram for Mild Steel
The stress-strain curve for mild steel shows the relationship between stress (force per unit area) and strain (deformation per unit length). Key features:
Proportional Limit (A): Linear relationship between stress and strain; obeys Hooke's Law.
Elastic Limit (B): Maximum stress at which the material returns to its original shape when the load is removed.
Yield Point (C): Sudden elongation occurs at constant stress. Divided into:
Upper Yield Point.
Lower Yield Point.
Ultimate Stress (D): Maximum stress the material can withstand.
Fracture Point (E): The material breaks.
Sketch:
X-axis: Strain
Y-axis: Stress
Mark points A, B, C, D, E.
1. b) Types of Loads and Supports with Symbols and Reactions
Types of Loads
Concentrated Load (Point Load): Acts at a specific point.
Distributed Load: Spreads over a length (uniform or varying).
Moment Load: Rotational force about a point.
Types of Supports
Roller Support
Symbol: A small circle or roller.
Reaction: One vertical reaction.
Degree of Freedom: 2 (can move horizontally and rotate).
Pinned Support
Symbol: A triangle or hinge.
Reaction: Vertical and horizontal reactions.
Degree of Freedom: 1 (can rotate).
Fixed Support
Symbol: Solid block.
Reaction: Vertical, horizontal reactions, and moment.
Degree of Freedom: 0 (no movement allowed).
Sketch each support and corresponding reactions.
2. a) Definition and Types of Truss
Definition: A truss is a framework of interconnected members forming triangular units to bear loads efficiently.
Types of Trusses:
Pratt Truss: Diagonals slope toward the center under tension.
Howe Truss: Diagonals slope outward under compression.
Warren Truss: Alternating equilateral triangles.
K-Truss: Members form a "K" shape.
Sketch each truss for clarity.
2. b) Nature and Magnitude of Forces in Members
For the given truss with a 1500 N load:
Identify joints and use Method of Joints or Method of Sections.
Resolve forces at each joint.
State nature:
Tensile: Pulls the member.
Compressive: Pushes the member.
(Sketch and calculations will depend on the detailed truss figure provided.)
4. a) Definitions
Axial Force: Force along the axis of a member (tensile or compressive).
Shear Force: Internal force parallel to the cross-section, resisting sliding.
Bending Moment: The rotational effect of forces causing bending.
4. b) Shear Force and Bending Moment Diagram for the Beam
For the given overhanging beam:
Shear Force Diagram (SFD):
Start with support reactions.
Add contributions from point loads and distributed loads.
Bending Moment Diagram (BMD):
Integrate shear force over the length.
Identify points of zero shear for maximum bending moments.
Procedure:
Use equilibrium equations:
Σ
𝐹
𝑦
=
0
,
Σ
𝑀
=
0
ΣF
y
=0,ΣM=0
Calculate reactions at supports.
Plot SFD and BMD step by step.
Determine Positive Bending Moment:
Solve for the position in the central bay where the bending moment transitions from positive to negative.
Identify max positive and negative moments using the SFD.
(Sketch detailed SFD and BMD with calculations based on the given dimensions and loads.)
