BT-204 Basic Civil Engineering and Engineering Mechanics - Nov 2022 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWrite about physical and chemical properties of concrete.
   How to answer

   • Physical properties: Workability, compressive strength, tensile strength, elasticity, creep, shrinkage, durability, permeability.
   • Chemical properties: Hydration of cement, alkali-aggregate reaction, sulfate attack, carbonation, resistance to acids/chlorides.
2. 7 Marks
   bExplain about the different types of stair case used in building construction with a neat sketch
   How to answer

   • Definition and purpose of staircase in buildings.
   • Classification: Straight, Dog-legged, Open-well (Open-newel), Quarter-turn, Bifurcated, Spiral/Helical stairs.
   • Brief explanation of features of each type.
   • Neat sketches/plans of major types (especially dog-legged and open-well).
3. 7 Marks
   aExplain the individual component of the Theodolite with a Sketch.
   How to answer

   • Neat labeled diagram of transit theodolite showing essential parts.
   • Explanation of components: Trivet and Tribrach, Levelling head/screws, Lower and Upper plates with verniers, Standards (A-frame), Telescope, Vertical circle, Plate levels, Compass, Plumb bob.
4. 7 Marks
   bNarrate about the classification of stone used in construction industry.
   How to answer

   • Geological classification: Igneous (granite, basalt), Sedimentary (sandstone, limestone), Metamorphic (marble, slate, quartzite).
   • Physical classification: Stratified, Unstratified, Foliated.
   • Chemical classification: Siliceous, Argillaceous, Calcareous.
   • Practical engineering uses of each classification.
5. 7 Marks
   aExplain in brief with about the Remote sensing and its application in construction
   How to answer

   • Definition and basic principle of remote sensing.
   • Components: Energy source, sensor, platform, data transmission, processing.
   • Applications in construction: Site investigation and planning, alignment of roads/railways, monitoring construction progress, water resources management, structural health monitoring, environmental impact assessment.
6. 7 Marks
   bState and derive the Lami's theorem and solve the problem given below using the theorem

   

   How to answer

   • Statement of Lami's theorem.
   • Derivation using force triangle and law of sines.
   • Identification of forces acting at the junction: Tension $T$ in inclined cable, horizontal force $P$, and vertical load $W = 100\text{ N}$.
   • Calculate angles between each pair of forces.
   • Apply Lami's theorem equation to solve for $P$ and string tension.
7. 7 Marks
   aDiscuss us about the Contour line, Contour Interval, Horizontal Interval and Use of Contour Map
   How to answer

   • Definition of Contour line: Line joining points of equal elevation.
   • Definition of Contour interval: Constant vertical distance between consecutive contours.
   • Definition of Horizontal interval / equivalent: Horizontal distance between two consecutive contour lines.
   • Uses of contour maps: Route selection, reservoir capacity determination, intervisibility, earthwork volume calculation, geological features identification.
8. 7 Marks
   bA block of mass $M = 10\text{ kg}$ is sitting on a surface inclined at angle $\theta = 45^\circ$. Given that the coefficient of static friction is $\mu_s = 0.5$ between block and surface, what is the minimum force $F$ necessary to prevent slipping? What is the maximum force $F$ that can be exerted without causing the block to slip?

   

   How to answer

   • Free body diagram with normal reaction $R = Mg\cos(45^\circ)$ and limiting friction $f_s = \mu_s R$.
   • Case 1 (impending downward slip): $F_{\min} + f_s = Mg\sin(45^\circ) \implies F_{\min} = Mg(\sin 45^\circ - \mu_s \cos 45^\circ)$.
   • Case 2 (impending upward slip): $F_{\max} = Mg\sin(45^\circ) + f_s = Mg(\sin 45^\circ + \mu_s \cos 45^\circ)$.
   • Calculate numerical values using $g = 9.81\text{ m/s}^2$ (or $9.8\text{ m/s}^2$).
   • $F_{\min} \approx 34.68\text{ N}$, $F_{\max} \approx 104.05\text{ N}$.
9. 7 Marks
   aIllustrate the difference between the Height of Collimation and Rise and Fall Method
   How to answer

   • Tabular comparison between Collimation method and Rise & Fall method.
   • HI method calculates height of instrument at each setup; intermediate RLs found by $HI - IS$. Faster, but no check on intermediate sights.
   • Rise and Fall method calculates relative rise/fall between consecutive points. Provides complete arithmetic check on intermediate stations.
   • Formulas for arithmetic checks for both methods.
10. 7 Marks
    bThe following are the consecutive reading were taken with a levelling instrument at intervals of $20\text{ m}$. $2.375$, $1.730$, $0.615$, $3.450$, $2.835$, $2.070$, $1.835$, $0.985$, $0.435$, $1.630$, $2.255$ and $3.630\text{ m}$. The instrument was shifted after the fourth and eight reading. The last reading was taken on a BM of RL $110.200\text{ m}$. Find the RLs of all the point using Rise and Fall method and satisfy the answer with arithmetic Check.
    How to answer

    • Set up Level Book columns: Station, Chainage, BS, IS, FS, Rise, Fall, RL, Remarks.
    • Classify readings: 1st setup: BS=2.375, IS=1.730, IS=0.615, FS=3.450 (4th reading); 2nd setup: BS=2.835, IS=2.070, IS=1.835, FS=0.985 (8th reading); 3rd setup: BS=0.435, IS=1.630, IS=2.255, FS=3.630 (12th reading).
    • Compute Rise and Fall for each interval.
    • Work backwards from the known last RL ($110.200\text{ m}$) or find first RL and forward calculate all RLs.
    • Apply arithmetic check: $\sum BS - \sum FS = \sum Rise - \sum Fall = \text{Last RL} - \text{First RL}$.
11. 6 Marks
    aDifferentiate the difference between Moment of inertia and Product of inertia.
    How to answer

    • Definition: $I_{xx} = \int y^2 dA$ (always positive) vs $I_{xy} = \int xy dA$ (can be positive, negative, or zero).
    • Physical meaning: Moment of inertia measures resistance to bending/rotation; Product of inertia is a measure of asymmetry about the coordinate axes.
    • Significance of symmetry: If either the x or y axis is an axis of symmetry, $I_{xy} = 0$.
    • Relation to principal axes.
12. 8 Marks
    bCalculate the Moment of Inertia about the X- axis.

    

    How to answer

    • Divide shaded composite area into standard components: Right triangular area in upper quadrant, semicircular lower area, minus the circular hole.
    • State dimensions from diagram: Semicircle of radius $50\text{ mm}$ below X-axis, right triangle of base $50\text{ mm}$ and height $100\text{ mm}$ above X-axis, central circular hole of diameter $50\text{ mm}$.
    • Compute $I_x$ of each component about the X-axis directly or via parallel axis theorem.
    • Sum individual contributions: $I_{xx} = I_{x,\text{triangle}} + I_{x,\text{semicircle}} - I_{x,\text{hole}}$.
    • Final value in $\text{mm}^4$.
13. 6 Marks
    aWrite about the difference between Method of Joint and Method of Section.
    How to answer

    • Method of Joints: Evaluates equilibrium of individual concurrent force systems at joints; uses $\sum F_x = 0, \sum F_y = 0$; best when all member forces are needed.
    • Method of Sections: Cuts the truss into two sections; uses non-concurrent coplanar equilibrium $\sum F_x = 0, \sum F_y = 0, \sum M = 0$; ideal for determining forces in specific internal members without solving the entire truss.
    • Tabular comparison outlining advantages and limitations of each.
14. 8 Marks
    bDraw the Shear force and Bending moment diagram for the simple supported beam carries a Uniform distributed load of intensity "W" kN/m throughout a span of length "L" m.
    How to answer

    • Calculate support reactions: $R_A = R_B = \frac{WL}{2}$.
    • Write shear force equations along length $x$: $V_x = \frac{WL}{2} - Wx$; value at ends $\pm \frac{WL}{2}$, zero at $x = \frac{L}{2}$.
    • Write bending moment equations: $M_x = \frac{WL}{2}x - \frac{Wx^2}{2}$; zero at supports, parabolic variation.
    • Maximum bending moment occurs at mid-span: $M_{\max} = \frac{WL^2}{8}$.
    • Draw neat, labeled SFD (linear slope) and BMD (parabolic curve).
15. 14 Marks
    Explain about the following Terms:

    1. a)Centroid and Centre of Gravity
    2. b)Profile Cross-sectioning
    3. c)Plane table and its used instruments
    How to answer

    • a) Centroid (geometric center of 1D/2D shapes) vs Centre of Gravity (point where total weight acts in 3D bodies). (5 marks)
    • b) Profile Cross-sectioning: Longitudinal and transverse leveling along a proposed route (road/canal/rail) to determine ground profile and earthwork quantities. (5 marks)
    • c) Plane table and accessories: Drawing board, tripod, alidade, trough compass, plumbing fork with plumb bob, spirit level. (4 marks)