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Sri Lanka Engineering Service Exam practice questions

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Question 1Civil Engineering

In reinforced concrete beam design to a limit-state code, the primary purpose of limiting the neutral-axis depth ratio (x/d) is to:

  1. Guarantee that shear reinforcement is no longer required
  2. Prevent shrinkage cracks from developing during curing
  3. Increase the modular ratio between steel and concrete
  4. Ensure the section fails in a ductile manner after visible steel yielding Correct answer.

Explanation

Limiting x/d keeps the tensile steel from being so heavy that the concrete crushes before the steel yields, producing a sudden brittle failure. A controlled under-reinforced section gives warning of distress through deflection and cracking before collapse.

Question 2Civil Engineering

A simply supported beam of span 6 m carries a uniformly distributed load of 20 kN/m over its full length. The maximum bending moment is:

  1. 60 kN·m
  2. 45 kN·m
  3. 180 kN·m
  4. 90 kN·m Correct answer.

Explanation

For a simply supported beam under a uniform load w over span L, the maximum moment is wL²/8. Substituting w = 20 kN/m and L = 6 m gives 20 × 36 / 8 = 90 kN·m at midspan.

Question 3Civil Engineering

In a singly reinforced concrete beam section, the lever arm between the compressive and tensile resultants is measured as the distance between:

  1. The neutral axis and the extreme compression fibre
  2. The centroid of the tension steel and the top fibre of the section
  3. The two supports of the beam
  4. The centroid of the compression zone and the centroid of the tension steel Correct answer.

Explanation

The internal resisting moment equals the force couple multiplied by the lever arm, which is the distance between the compression resultant and the tension resultant. The compression resultant acts at the centroid of the concrete stress block and the tension resultant at the steel centroid.

Question 4Civil Engineering

A soil sample has a void ratio of 0.65 and specific gravity of solids of 2.65. Its dry unit weight (taking unit weight of water as 9.81 kN/m³) is closest to:

  1. 12.6 kN/m³
  2. 18.9 kN/m³
  3. 15.8 kN/m³ Correct answer.
  4. 20.4 kN/m³

Explanation

Dry unit weight is γd = Gs·γw/(1 + e). Substituting Gs = 2.65, γw = 9.81 and e = 0.65 gives 26.0/1.65 ≈ 15.8 kN/m³.

Question 5Civil Engineering

According to Terzaghi's bearing capacity theory, the ultimate bearing capacity of a strip footing on cohesionless soil at the ground surface (zero surcharge and zero embedment) depends primarily on:

  1. The unit weight of soil, footing width and the bearing capacity factor Nγ Correct answer.
  2. Cohesion and adhesion
  3. The plasticity index of the soil
  4. The undrained shear strength only

Explanation

For a strip footing with no surcharge and no cohesion, the general bearing capacity equation reduces to qu = 0.5·γ·B·Nγ. Hence the width, soil unit weight and the friction-angle-dependent factor Nγ control the capacity.

Question 6Civil Engineering

In open channel flow, the Froude number is defined as V/√(gD), where D is the hydraulic depth. A flow with Froude number equal to 0.6 is classified as:

  1. Subcritical flow Correct answer.
  2. Critical flow
  3. Turbulent flow
  4. Supercritical flow

Explanation

The Froude number compares inertial to gravity forces; values below 1 indicate subcritical (tranquil) flow where disturbances travel upstream. A value of 0.6 is therefore subcritical.

Question 7Civil Engineering

The Chezy equation for uniform flow velocity in an open channel is expressed as V = C√(RS), where R is the hydraulic radius and S is the bed slope. The Manning equation relates C to the roughness coefficient n as:

  1. C = n·R^(1/6)
  2. C = (1/n)R^(2/3)
  3. C = (1/n)R^(1/6) Correct answer.
  4. C = n·R^(2/3)

Explanation

Equating the Chezy and Manning forms gives V = (1/n)R^(2/3)S^(1/2), so C = (1/n)R^(1/6) in SI units. The Manning n appears in the denominator because rougher channels have lower velocity.

Question 8Civil Engineering

In a hydrometer analysis used for particle size distribution of fine-grained soils, the method relies on:

  1. Stokes' law relating the settling velocity of particles to their diameter Correct answer.
  2. The capillary rise of water in the soil pores
  3. The electrical conductivity of the soil suspension
  4. Sieve openings retaining particles of known size

Explanation

Hydrometer analysis determines the percentage of particles finer than a given size by measuring the change in suspension density as particles settle. Stokes' law converts the settling velocity to an equivalent particle diameter.

Question 9Civil Engineering

In the standard Proctor compaction test, the compaction curve relating dry unit weight to water content typically shows:

  1. A peak dry unit weight at the optimum moisture content, decreasing on either side Correct answer.
  2. A continuous increase in dry unit weight with increasing water content
  3. No dependence of dry unit weight on water content
  4. A straight-line relationship between dry unit weight and water content

Explanation

At low water content, friction between particles resists densification; as water increases, lubrication improves compaction until an optimum moisture content is reached. Beyond that point, trapped water displaces soil solids and the dry unit weight falls.

Question 10Civil Engineering

A retaining wall 5 m high retains dry cohesionless backfill with unit weight 18 kN/m³ and angle of internal friction 30°. Using Rankine theory and ignoring wall friction, the total active earth pressure per metre length is closest to:

  1. 225 kN/m
  2. 37.5 kN/m
  3. 112.5 kN/m
  4. 75 kN/m Correct answer.

Explanation

Rankine active coefficient is Ka = (1 − sinφ)/(1 + sinφ) = 1/3 for φ = 30°. The pressure at the base is Ka·γ·H = 1/3 × 18 × 5 = 30 kPa, giving a triangular distribution with total force 0.5 × 30 × 5 = 75 kN/m.

Question 11Civil Engineering

The nominal mix designation M20 in concrete work indicates a characteristic cube compressive strength of:

  1. 20 N/mm² at 28 days Correct answer.
  2. 20 N/mm² at 7 days
  3. 200 N/mm² at 28 days
  4. 2 N/mm² at 28 days

Explanation

The grade designation M20 denotes the characteristic compressive strength of 20 N/mm² measured on 150 mm cubes at 28 days, with a defined probability of not being exceeded. Grades are specified at the standard 28-day curing age.

Question 12Civil Engineering

A slump test on a concrete mix gives a very low slump value. The most likely interpretation is that the mix:

  1. Is stiff and has low workability for the given conditions Correct answer.
  2. Contains too much entrained air
  3. Has achieved its design compressive strength
  4. Has a high workability and is likely to segregate

Explanation

Slump is an empirical measure of consistency and workability; a low slump indicates a stiff, dry mix that is harder to place and compact. It says nothing directly about strength or air content.

Question 13Civil Engineering

In a two-way slab supported on four edges, load transfer is assumed to occur:

  1. Entirely in the long span direction
  2. Entirely in the short span direction
  3. Equally in both directions regardless of aspect ratio
  4. In both directions, with a larger share carried by the short span Correct answer.

Explanation

A two-way slab deflects into a dished surface and transfers load along both spans. Because the short span is stiffer, it attracts a larger proportion of the load, which is why distribution coefficients depend on the aspect ratio.

Question 14Civil Engineering

In structural steel design, the purpose of providing a stiffener on a plate girder web is primarily to:

  1. Reduce the tendency of the thin web to buckle under shear and concentrated loads Correct answer.
  2. Prevent corrosion of the web surface
  3. Increase the yield strength of the web plate
  4. Reduce the self-weight of the girder

Explanation

Thin webs can buckle at stresses well below yield, so intermediate and bearing stiffeners are added to divide the web into smaller panels and raise its buckling resistance. Stiffeners do not change the steel's yield strength.

Question 15Civil Engineering

A steel rod of length 2 m and cross-sectional area 500 mm² is subjected to an axial tensile force of 100 kN. Taking Young's modulus as 200 GPa, the elongation is:

  1. 4.0 mm
  2. 2.0 mm Correct answer.
  3. 0.2 mm
  4. 0.5 mm

Explanation

Elongation is δ = PL/(AE). Substituting P = 100,000 N, L = 2000 mm, A = 500 mm² and E = 200,000 N/mm² gives 2 × 10⁸ / 10⁸ = 2.0 mm.

Question 16Civil Engineering

In a simply supported truss, a member carrying zero force under the given load condition is best identified by:

  1. Applying equilibrium at a joint where only two non-collinear members meet and no external load acts Correct answer.
  2. Computing the member's self-weight
  3. Measuring the member's cross-sectional area
  4. Checking the member's slenderness ratio

Explanation

At a joint with exactly two non-collinear members and no external load or support reaction, resolving forces shows both members must carry zero force. This is the standard zero-force member rule for truss analysis.

Question 17Civil Engineering

In surveying, the term 'closing error' in a closed traverse refers to:

  1. The angle between magnetic north and true north
  2. The difference between the measured and computed coordinates after the traverse returns to its starting point Correct answer.
  3. The error in reading the levelling staff
  4. The distance between two consecutive instrument stations

Explanation

In a closed traverse, the algebraic sum of latitudes and departures should be zero; any residual discrepancy is the closing error. It is distributed across the survey by a balancing method such as the Bowditch rule.

Question 18Civil Engineering

The Bowditch (compass) rule for adjusting a closed traverse distributes the closing error in proportion to:

  1. The magnetic bearing of each line
  2. The elevation difference between stations
  3. The length of each traverse leg relative to the total perimeter Correct answer.
  4. The interior angles at each station

Explanation

The Bowditch rule assumes errors arise mainly from linear measurement and distributes the latitude and departure corrections proportionally to leg length over total perimeter. It is appropriate for traverses where distance errors dominate over angular errors.

Question 19Civil Engineering

In a water supply distribution network, the Hazen-Williams formula is commonly used to estimate:

  1. The settling velocity of grit particles
  2. Head loss due to friction in a pipe flowing full Correct answer.
  3. The biological oxygen demand of wastewater
  4. The rate of infiltration into the soil

Explanation

The Hazen-Williams equation is an empirical head-loss formula for turbulent flow in full pipes, using a roughness coefficient C, flow rate and pipe diameter. It is widely used for water distribution network analysis.

Question 20Civil Engineering

A primary sedimentation tank in a wastewater treatment plant is designed on the basis of:

  1. The air flow rate of the blowers
  2. Surface overflow rate (surface loading rate) Correct answer.
  3. The sludge digestion time
  4. The chlorine demand of the effluent

Explanation

Primary sedimentation performance is governed by the surface overflow rate, expressed as flow per unit surface area per day, which corresponds to the settling velocity of particles to be removed. Detention time and depth are checked as secondary criteria.

Question 21Civil Engineering

In highway geometric design, superelevation is provided on a horizontal curve primarily to:

  1. Drain the surface water towards the inner edge
  2. Counteract the centrifugal force experienced by moving vehicles Correct answer.
  3. Reduce the pavement thickness requirement
  4. Increase the sight distance along the curve

Explanation

Superelevation banks the roadway so that a component of vehicle weight helps balance the centrifugal force, improving comfort and safety at speed. It is designed together with the side-friction factor in the curve equation.

Question 22Civil Engineering

The CBR (California Bearing Ratio) value of a subgrade soil is used in pavement design to:

  1. Measure the skid resistance of the finished surface
  2. Estimate the required pavement thickness for a given traffic loading Correct answer.
  3. Determine the bitumen content of the surface course
  4. Compute the camber of the carriageway

Explanation

CBR expresses the strength of the subgrade or granular layer relative to a standard crushed stone, and is an input to empirical pavement thickness design methods. It reflects the load-spreading capability of the supporting layers.

Question 23Civil Engineering

In a concrete mix, the main role of entrained air is to:

  1. Reduce the cement content required for a given strength
  2. Accelerate the setting time of the mix
  3. Improve resistance to freezing and thawing damage Correct answer.
  4. Increase the compressive strength of the hardened concrete

Explanation

Entrained air bubbles provide space for freezing water to expand, relieving internal pressure and improving freeze-thaw durability. The trade-off is a small reduction in compressive strength.

Question 24Civil Engineering

A cantilever retaining wall is to be checked for stability. Which combination of checks is essential?

  1. Acoustic insulation and thermal conductivity
  2. Fire rating and smoke development
  3. Overturning, sliding and bearing pressure at the base Correct answer.
  4. Colour uniformity and surface texture

Explanation

Retaining wall stability requires verification against overturning about the toe, sliding along the base, and bearing capacity or eccentricity of the base pressure. These three checks ensure the wall remains serviceable under lateral earth pressure.

Question 25Civil Engineering

In a reinforced concrete column subjected to combined axial load and uniaxial bending, the interaction diagram relates:

  1. Axial load capacity and applied bending moment at a given section Correct answer.
  2. Shear force and torsion
  3. Soil bearing capacity and settlement
  4. Concrete slump and compaction factor

Explanation

The interaction diagram plots the axial load capacity against the moment capacity for a section, defining the safe combinations of P and M. Design points must lie within the envelope bounded by the balanced and pure-bending or pure-axial extremes.

Question 26Civil Engineering

In reinforced concrete design to a limit-state code, the partial safety factor for the strength of concrete (γm) is applied to the characteristic cube strength primarily because:

  1. the partial safety factor accounts for the self-weight of the member
  2. concrete strength increases with age so the design value must be reduced to the 28-day value
  3. the characteristic strength is a statistical fractile and material strength in the structure is lower than the cube value Correct answer.
  4. the cube test is carried out on dry specimens while the structure is saturated

Explanation

The characteristic strength is defined as the value below which no more than 5% of test results are expected to fall, so it already represents a lower fractile of cube strength. The cube strength also overstates the in-situ strength because of casting, compaction and curing differences. The partial safety factor converts this characteristic value into a design strength that carries an accepted probability of being exceeded in the unfavourable direction.

Question 27Civil Engineering

A simply supported reinforced concrete beam of effective span 6 m carries a uniformly distributed load. If the overall depth is limited to 500 mm and moderate exposure applies, the span-to-effective-depth ratio check is used mainly to:

  1. ensure the beam has adequate shear reinforcement
  2. control deflection without a full deflection calculation Correct answer.
  3. limit the crack width at the tension face
  4. prevent local crushing of concrete under the bearing plate

Explanation

Codes give limiting span-to-effective-depth ratios so that members satisfying them may be assumed not to deflect excessively, avoiding a full deflection calculation. The limit depends on the support conditions and the permitted modification for reinforcement ratio. It is a serviceability control rather than a strength check.

Question 28Civil Engineering

A rectangular reinforced concrete section is reinforced with tension steel only and is designed as under-reinforced. At the ultimate limit state, the flexural failure is expected to be:

  1. sudden crushing of concrete in the compression zone before the steel yields
  2. shear failure along a diagonal crack near the support
  3. ductile yielding of tension steel followed by concrete crushing Correct answer.
  4. bond slip of the bars before any yielding occurs

Explanation

In an under-reinforced section the steel reaches its yield strain before the concrete reaches its ultimate compressive strain. The section therefore yields and deflects noticeably before the concrete crushes, giving a ductile warning of failure. Over-reinforced sections behave the opposite way and fail by brittle concrete crushing.

Question 29Civil Engineering

In a singly reinforced concrete beam, the lever arm between the compressive and tensile resultants is generally taken as approximately 0.9 times the effective depth for normal reinforcement ratios. The bending moment of resistance is best expressed as:

  1. 0.67 fck b × 0.9 d
  2. 0.87 fy As × 0.9 d Correct answer.
  3. fy As × 0.5 d
  4. 0.87 fy As × d

Explanation

The tensile force at ultimate limit state is the design yield stress of the steel (0.87 fy) multiplied by the steel area, and the internal lever arm is about 0.9 d for typical under-reinforced sections. The moment of resistance is the product of the tensile force and the lever arm. Using the full depth d overestimates the lever arm and hence the capacity.

Question 30Civil Engineering

A short reinforced concrete column carries a factored axial load of 1500 kN with a small eccentricity. When checking the column, the minimum eccentricity requirement exists mainly to:

  1. prevent the column from buckling about its weak axis
  2. ensure the column is always in double curvature
  3. allow for accidental imperfections and unavoidable construction tolerances Correct answer.
  4. guarantee that the steel yields before the concrete

Explanation

No column is loaded perfectly axially in practice; construction tolerances, misalignment and accidental eccentricity introduce bending. Codes therefore require a minimum eccentricity so the design includes a nominal moment. This avoids an unsafe assumption of pure axial compression.

Question 31Civil Engineering

A steel tension member of a roof truss is connected by a single line of bolts through one leg of an angle. The design tensile strength must be based on the net section because:

  1. the holes remove area and create stress concentration at the net section Correct answer.
  2. the member is in compression during uplift
  3. bolting reduces the yield strength of the steel locally
  4. the gross section governs only for welded connections

Explanation

Bolt holes reduce the cross-sectional area resisting tension, so the net section may control even though the gross section carries the lower average stress. Stress concentration around the holes further reduces the effective capacity. Codes therefore require checks on both gross yielding and net-section rupture.

Question 32Civil Engineering

A steel beam of span 8 m is laterally unsupported over its full length and carries a uniformly distributed load on its top flange. The design bending strength will be reduced below the plastic moment capacity mainly because:

  1. shear lag between the flanges and the web becomes significant
  2. the web cripples under the concentrated load
  3. lateral torsional buckling of the compression flange can occur Correct answer.
  4. the beam self-weight exceeds the applied load

Explanation

When the compression flange is unrestrained, the beam can buckle sideways and twist, a mode called lateral torsional buckling. The resistance then depends on the unbraced length, the section properties and the moment gradient, and falls below the full plastic capacity. Providing lateral restraints at closer spacing restores the higher capacity.

Question 33Civil Engineering

A bolted connection in a steel structure uses ordinary black bolts in clearance holes and is subjected to a load reversing in direction. The connection should preferably be designed as:

  1. a welded connection with fillet welds only on one side
  2. a friction-grip connection with preloaded high-strength bolts Correct answer.
  3. a bearing-type connection with the bolts in shear
  4. a connection relying on the clamping force of the bolts only in tension

Explanation

Reversals of load cause slip and wear in clearance-hole bearing connections, leading to fatigue and loosening. Preloaded high-strength friction-grip bolts clamp the plates so that load is transferred by friction without slip. This gives a stiff connection better suited to cyclic or reversing loads.

Question 34Civil Engineering

A soil sample taken from below the water table is to be tested for shear strength in the laboratory. To determine the effective stress parameters c′ and φ′, the test must be conducted:

  1. with full consolidation and with pore pressure measurement during shearing Correct answer.
  2. as a compaction test at the field dry density
  3. as an unconsolidated undrained triaxial test with pore pressure not measured
  4. as a quick direct shear test at the natural water content

Explanation

Effective stress parameters require that volume change be allowed to complete during consolidation and that excess pore pressure be measured during shear. The effective stresses are then obtained by subtracting pore pressure from total stress. Undrained tests without pore pressure measurement yield only total stress parameters.

Question 35Civil Engineering

A clay layer 4 m thick is subjected to a uniform increase in vertical stress of 50 kPa. Taking the coefficient of volume compressibility as 0.0003 m²/kN, the primary consolidation settlement is:

  1. 600 mm
  2. 6 mm
  3. 60 mm Correct answer.
  4. 0.6 mm

Explanation

Consolidation settlement equals the coefficient of volume compressibility multiplied by the stress increase and the layer thickness. Here 0.0003 m²/kN × 50 kN/m² × 4 m gives 0.06 m, which is 60 mm. The units must be kept consistent throughout.

Question 36Civil Engineering

In a triaxial compression test on saturated sand, the sample is consolidated at a confining pressure of 100 kPa and fails when the axial stress difference reaches 300 kPa. The major principal effective stress at failure is:

  1. 300 kPa
  2. 400 kPa Correct answer.
  3. 100 kPa
  4. 200 kPa

Explanation

In a triaxial test the cell pressure acts as the minor principal stress and the deviator stress is added axially. The major principal stress is therefore the confining pressure plus the deviator stress. With 100 kPa plus 300 kPa the result is 400 kPa, and because the sand is drained the effective stresses equal the total stresses.

Question 37Civil Engineering

A gravity retaining wall is founded on a stiff clay and is checked for bearing pressure. For no tension to develop at the base, the resultant of vertical and horizontal forces must lie:

  1. within the outer third of the base near the heel
  2. within the middle third of the base width Correct answer.
  3. exactly at the centre of the base at all times
  4. at the toe of the wall

Explanation

If the resultant falls outside the middle third, the eccentricity exceeds one-sixth of the base width and the computed pressure at the heel becomes tensile. Since soil cannot sustain tension, the base would tend to lift and the pressure distribution would be non-linear. Keeping the resultant within the middle third ensures the whole base remains in compression.

Question 38Civil Engineering

A rectangular channel 3 m wide carries a discharge of 9 m³/s at a normal depth of 1.5 m. The specific energy at this section, taking the velocity head into account, is closest to:

  1. 2.7 m
  2. 1.5 m
  3. 1.8 m Correct answer.
  4. 2.1 m

Explanation

The velocity is discharge divided by the flow area, giving 9 divided by 4.5, or 2 m/s. The velocity head is V²/2g, equal to 4 divided by 19.62, or about 0.20 m. Adding this to the depth of 1.5 m gives a specific energy of approximately 1.7 to 1.8 m, so 1.8 m is the closest choice.

Question 39Civil Engineering

A centrifugal pump is to deliver water through a rising main. If the static lift is 20 m and the total head loss in the pipe is 5 m at the design discharge, the pump total head required at that discharge is:

  1. 20 m
  2. 30 m
  3. 15 m
  4. 25 m Correct answer.

Explanation

The total head developed by the pump must equal the static lift plus all losses in the suction and delivery pipework plus the velocity head at the outlet. With a static lift of 20 m and friction and minor losses of 5 m, the required total head is 25 m. The pump operating point is then the intersection of this system curve with the pump characteristic.

Question 40Civil Engineering

A town of 100,000 people is to be supplied with water at a per capita demand of 150 litres per day. The peak factor for the maximum daily demand is 1.5 and for the peak hourly demand is 2.7 times the average daily demand. The maximum hourly flow rate to be used for distribution main design is closest to:

  1. 62.5 ML/d
  2. 15.6 ML/d
  3. 40.5 ML/d Correct answer.
  4. 23.4 ML/d

Explanation

The average daily demand is 100,000 × 150 litres, which equals 15 million litres per day. The peak hourly demand is obtained by applying the peak factor of 2.7 to this average daily demand, giving about 40.5 ML/d. This higher rate governs the sizing of distribution mains, while the maximum daily rate governs treatment and transmission works.

Question 41Structural Engineering

In reinforced concrete design to BS 8110, which parameter primarily determines the ultimate moment of resistance of a singly reinforced rectangular section with a given effective depth?

  1. The characteristic cube strength of concrete alone
  2. The diameter of the aggregate used in the mix
  3. The area and yield strength of tension steel relative to the concrete compressive capacity Correct answer.
  4. The span-to-depth ratio of the member

Explanation

The moment of resistance depends on the balance between the tension force in the steel (area times design strength) and the compression force in the concrete (stress block times lever arm). The steel ratio relative to the concrete capacity determines whether the section is under-reinforced or over-reinforced. Aggregate size and span ratio do not enter the section capacity calculation directly.

Question 42Structural Engineering

A simply supported beam of span 6 m carries a uniformly distributed load of 20 kN/m including self-weight. What is the maximum bending moment?

  1. 60 kNm
  2. 180 kNm
  3. 120 kNm
  4. 90 kNm Correct answer.

Explanation

For a simply supported beam under a uniformly distributed load w over span L, the maximum moment is wL²/8. Substituting 20 kN/m and 6 m gives 20 × 36 / 8 = 90 kNm. This occurs at midspan.

Question 43Structural Engineering

According to limit state design philosophy, which limit state concerns the safety of people and the structure under extreme loading?

  1. Durability limit state
  2. Ultimate limit state Correct answer.
  3. Fatigue limit state
  4. Serviceability limit state

Explanation

The ultimate limit state addresses collapse, loss of equilibrium, and structural failure that endanger life. Design checks ensure the structure resists factored extreme loads with adequate safety margins. Serviceability concerns deflection and cracking under normal use.

Question 44Structural Engineering

In structural steel design, what does the yield strength of the steel represent?

  1. The maximum stress the material can sustain before necking
  2. The stress at which the material fractures
  3. The stress corresponding to the proportional limit only
  4. The stress at which the material begins to deform plastically Correct answer.

Explanation

Yield strength is the stress at which the material transitions from elastic to plastic behaviour, producing permanent deformation. It is the key parameter for most steel design checks. Fracture and ultimate stresses occur at much higher strains.

Question 45Structural Engineering

Which of the following is the primary purpose of providing shear reinforcement (stirrups) in a reinforced concrete beam?

  1. To improve the fire resistance of the concrete cover
  2. To resist diagonal tension and prevent brittle shear failure Correct answer.
  3. To increase the flexural compressive capacity of the section
  4. To reduce the self-weight of the beam

Explanation

Stirrups resist the diagonal tension stresses that develop near supports and prevent sudden brittle shear failure. They also confine the concrete and restrain longitudinal bars. They do not contribute significantly to flexural compression capacity.

Question 46Structural Engineering

What is the main function of a foundation in a building structure?

  1. To provide lateral bracing to the upper floors
  2. To transfer loads from the superstructure safely to the ground Correct answer.
  3. To resist wind uplift on the roof
  4. To reduce the dead load carried by columns

Explanation

Foundations distribute the loads from columns and walls over a sufficient area of soil or rock so that bearing pressures remain within safe limits and settlements are controlled. Lateral bracing and roof uplift are handled by other structural elements.

Question 47Structural Engineering

Which structural material property is measured by the modulus of elasticity?

  1. The energy absorbed before fracture
  2. The resistance to indentation
  3. The stiffness of the material in the elastic range Correct answer.
  4. The tendency to creep under sustained load

Explanation

The modulus of elasticity is the ratio of stress to strain in the linear elastic region, representing the stiffness of the material. A high modulus means less deformation for a given stress. Energy absorption and hardness are separate properties.

Question 48Structural Engineering

In a reinforced concrete slab, what is the purpose of distribution steel placed perpendicular to the main reinforcement?

  1. To provide anchorage for the main bars
  2. To carry the entire bending moment in the short direction
  3. To increase the effective depth of the slab
  4. To resist shrinkage and temperature stresses and to distribute loads Correct answer.

Explanation

Distribution steel runs perpendicular to the main bars to control shrinkage and temperature cracking and to spread concentrated loads across the slab. It is not designed to carry the primary bending moment. It does not change effective depth.

Question 49Structural Engineering

A cantilever beam of length 2 m carries a point load of 15 kN at its free end. What is the maximum bending moment at the fixed support?

  1. 30 kNm Correct answer.
  2. 7.5 kNm
  3. 15 kNm
  4. 60 kNm

Explanation

For a cantilever with an end point load P over length L, the fixed-end moment is P × L. Here 15 kN × 2 m = 30 kNm, producing tension on the top face. This is the maximum moment in the beam.

Question 50Structural Engineering

In BS 8110, the design concrete shear stress vc for a section depends on which combination of parameters?

  1. Concrete grade, longitudinal steel ratio, and effective depth Correct answer.
  2. Concrete cover and bar spacing only
  3. Steel yield strength and aggregate size only
  4. Span and loading only

Explanation

The design concrete shear stress vc is read from a table based on the concrete cube strength, the percentage of longitudinal tension steel, and the effective depth. Deeper sections and higher steel ratios increase vc up to a limit. Span, loading, and cover do not directly enter the vc table.