Question 1

Brick Bonds – Appropriate bond for a 10 cm thick (half-brick) partition wall For constructing a 10 cm thick internal partition wall (approximately half-brick thick), which brick bond is most appropriate?

Accepted Answer

Introduction / Context: Brick bonds control strength, stability, and appearance. Half-brick partition walls (about 100–115 mm thick depending on brick size) are non-loadbearing and are typically laid to maximize speed and face finish using continuous stretcher courses. Given Data / Assumptions: Wall thickness ≈ 10 cm (half-brick). Internal partition, generally non-loadbearing. Standard modular bricks laid with mortar joints. Concept / Approach: Stretcher bond consists of bricks laid with the long face (stretcher) exposed, course after course, with half-brick overlaps. Header or English/Flemish bonds require full-brick thickness to interlock headers, which is not possible in half-brick walls. Step-by-Step Solution: Identify wall as half-brick thickness.Choose bond that does not require through headers: stretcher bond.Exclude bonds designed for one-brick thickness (≈ 20–23 cm) or more. Verification / Alternative check: Specifications for non-loadbearing partitions routinely prescribe stretcher bond, sometimes with reinforcement (e.g., at every third or fourth course) to control cracking. Why Other Options Are Wrong: English/Flemish/header bonds need headers across wall thickness; not feasible in half-brick thickness. Rat-trap bond creates cavities and uses brick on edge; not standard for 10 cm plain partitions. Common Pitfalls: Assuming decorative Flemish bond can be used in half-brick partitions; true interlocking requires greater thickness. Final Answer: Stretcher bond

Question 2

Pile Foundations – Name of a pile that carries load by both shaft friction and end bearing In foundation engineering, what is the correct term for a pile that derives part of its capacity from skin (shaft) friction along the pile–soil interface and …

Accepted Answer

Introduction / Context: Pile capacity is mobilized through two primary mechanisms: shaft (skin) friction and end (toe) bearing. In many practical sites, neither mechanism alone dominates completely; instead, a pile behaves as a composite element where both contributions matter. Identifying the correct terminology helps in interpreting calculation methods and test results. Given Data / Assumptions: Pile embedded through layered soils with a competent stratum at depth. Axial loading considered under service and ultimate states. Both shaft friction and toe resistance are mobilized under load. Concept / Approach: A purely friction pile develops capacity mainly through skin friction along its embedded length, typically in soft or medium soils without a firm bearing stratum. A purely end-bearing pile transfers most load to a hard stratum at the toe. When both mechanisms are significant, the correct description is a friction–bearing pile (also written friction-cum-end-bearing pile). Design sums the two components, often with reduction factors for compatibility and settlement criteria. Step-by-Step Solution: Recognize that capacity Q = Q_shaft + Q_base for a combined-action pile.Terminology: if both terms are non-negligible, the pile is called a friction bearing pile.Exclude extremes: friction-only or bearing-only labels do not capture the combined mechanism. Verification / Alternative check: Pile load tests (maintained load) show settlement–load curves where both shaft and base contributions are mobilized progressively. Static formulae integrate unit skin resistance and base resistance; dynamic correlations recognize both mechanisms as well. Why Other Options Are Wrong: “Friction pile” implies negligible end bearing; “bearing pile” implies dominant toe resistance; “rough pile” is not a standard term; “floating pile” usually indicates no firm toe stratum. Common Pitfalls: Assuming linear addition without considering settlement compatibility; overlooking negative skin friction; ignoring partial mobilization under service loads. Final Answer: Friction bearing pile (combined action)

Question 3

Brick Bonds – Identify the incorrect statement about English and Flemish bonds Consider the following statements about common brick bonds used in wall construction. Which statement is incorrect with respect to standard definitions and coursing pract…

Accepted Answer

Introduction / Context: Bonding patterns control strength, appearance, and joint distribution in brick masonry. English and Flemish bonds are the most cited in examinations and practice. Understanding their coursing rules avoids errors at site and during quantity takeoff. Given Data / Assumptions: Standard one-brick-thick walls with proper closers at quoins. Terminology: header shows the end face; stretcher shows the long face. Conventional coursing as per handbooks and codes. Concept / Approach: English bond is defined by alternate courses—one entire course of headers followed by one entire course of stretchers. Flemish bond alternates header and stretcher within the same course, repeating across the wall length, with queen closers at returns to maintain bond. Therefore, any statement that claims “English bond has stretchers in every course” contradicts the definition. Step-by-Step Solution: Check Option A: Correct—Flemish alternates within each course.Check Option B: Correct—Flemish positioning centers headers over stretchers below with closers at corners.Check Option C: Incorrect—English alternates full courses of headers and stretchers, not stretchers in every course.Check Option D: Correct—this is the defining rule of English bond. Verification / Alternative check: Standard diagrams in masonry texts and IS code illustrations confirm the coursing and the need for closers in both bonds to maintain lap at quoins. Why Other Options Are Wrong: Options A, B, and D are consistent with standard practice; Option E (“None”) is therefore false. Common Pitfalls: Omitting queen closers at corners; confusing elevation appearance with plan bond; miscounting course sequence while drafting. Final Answer: In English bond, stretchers are laid in every course.

Question 4

Arches – Where is the crown located? In arch terminology used in building construction, the “crown” refers to which specific location on an arch?

Accepted Answer

Introduction / Context: Precise terminology helps in detailing arches, calculating geometry, and communicating site instructions. Words like intrados, extrados, springing, skewback, haunch, crown, and keystone each point to a distinct feature of the arch geometry and construction sequence. Given Data / Assumptions: An arch ring with clearly defined inner (intrados) and outer (extrados) curves. Symmetric arch for simplicity, though the definition holds in general. Conventional building construction terminology. Concept / Approach: The intrados (soffit) is the lower curved surface of the arch visible from below. The crown is the highest point along this inner curve—essentially the topmost point of the soffit. While the extrados also has a highest point, the term “crown” conventionally refers to the intrados position; detailing such as crown thickness or crown height relates to this location. Step-by-Step Solution: Identify surfaces: intrados = inner/soffit; extrados = outer/top surface.Definition: crown = topmost point on the intrados curve.Exclude skewback: inclined seat at springing on the support.Confirm choice: Option B matches the accepted definition. Verification / Alternative check: Construction manuals and architectural dictionaries illustrate the crown at the highest intrados point; keystone sits near the crown in many arches but the term “crown” names the geometric location, not the specific stone. Why Other Options Are Wrong: Option A refers to the outer curve; Option C misplaces the term; Option E confuses impost with keystone location; “None” is inapplicable. Common Pitfalls: Equating the crown with the keystone only; mixing intrados and extrados; assuming the crown refers to the outer surface. Final Answer: The highest point on the intrados (soffit) of the arch

Question 5

Foundations on Low Bearing Capacity Soils – Which foundation type is generally adopted? When the soil at shallow depth has low allowable bearing capacity and differential settlement must be minimized, which foundation type is commonly provided for b…

Accepted Answer

Introduction / Context: Foundation selection balances bearing capacity, settlement control, constructability, and cost. On weak, relatively uniform soils, spreading loads over a larger area reduces contact pressure and helps limit differential settlement. This is the basis for choosing raft (mat) foundations in many low-capacity scenarios. Given Data / Assumptions: Soil near the surface has low bearing capacity at the required founding level. Building has multiple columns/walls requiring support. Objective is to reduce bearing pressure and differential settlement. Concept / Approach: A raft (mat) footing is a large, continuous slab supporting many or all columns and walls, effectively distributing loads across the entire building footprint. By increasing foundation area, the average contact pressure is reduced, and the raft’s rigidity helps bridge local soil variability. Grillage footings serve primarily to spread a concentrated load from a column (often steel) and are less suited for whole-building distribution on weak soils compared with a full mat. Isolated column footings may be inadequate or lead to large, overlapping pads in weak soils. Step-by-Step Solution: Assess soil and loads: low capacity + many supports → need large, rigid base.Select raft/mat: continuous slab under most or all columns/walls.Reject alternatives: isolated or grillage footings are piecemeal and may not control differential settlement adequately. Verification / Alternative check: Rules of thumb: when the sum of isolated footing areas exceeds ~50% of the footprint, a raft is economical and performs better. Analytical settlement checks confirm improved performance on soft soils. Why Other Options Are Wrong: Isolated footings demand large sizes and may settle unevenly; grillage is localized; answering “All” would include inferior choices for the stated condition. Common Pitfalls: Ignoring groundwater effects and punching shear; not considering basement integration; overlooking need for soil improvement under the raft when necessary. Final Answer: Raft footing

Question 6

Stability of Existing Structures – Which external factors can disturb it? For an existing building or structure, which of the following external changes in the environment can adversely affect its stability and serviceability?

Accepted Answer

Introduction / Context: Structures are designed for a set of assumed boundary conditions and soil–structure interactions. Changes around a building can disrupt those assumptions, leading to distress, differential settlements, and even instability. Recognizing these external risk factors is crucial for asset management and urban construction planning. Given Data / Assumptions: Existing structure with foundations bearing on soil strata. Neighbouring works or environmental changes may occur after construction. No special underpinning or protection unless implemented proactively. Concept / Approach: Rising water tables reduce effective stress and increase pore pressures, potentially lowering bearing capacity and causing buoyancy issues in basements. Traffic-induced vibrations can fatigue connections, loosen masonry, or aggravate settlement in loose granular soils. Mining or tunnelling creates ground movements and subsidence troughs. Adjacent excavations remove lateral confinement and can trigger basal heave or wall movements, transmitting settlements to nearby foundations. Step-by-Step Solution: Option A: Higher groundwater → lower effective stress, potential uplift/softening.Option B: Vibrations → serviceability problems, possible resonance or densification.Option C: Mining/tunnelling → subsidence and ground loss impacting foundations.Option D: Nearby excavation → changes in stress paths and lateral support; can induce settlement.Therefore, all listed factors can disturb stability. Verification / Alternative check: Case histories show façade cracking and tilt near deep excavations; structures near subway or traffic corridors often require vibration monitoring; groundwater control is a standard part of basement design and asset protection. Why Other Options Are Wrong: Each single choice omits other real hazards; “All” best captures the breadth of risks. Common Pitfalls: Underestimating cumulative effects; ignoring time-dependent consolidation after groundwater changes; failing to instrument adjacent structures during construction. Final Answer: All of the above

Question 7

Stucco Plaster – Names of the three coats in conventional three-coat work In traditional three-coat stucco plastering, what are the standard names of the first, second, and third coats applied in sequence?

Accepted Answer

Introduction / Context: Stucco plastering traditionally uses three layers to achieve durability, flatness, and finish quality. Each coat has a specific purpose and composition, and knowing their names is essential for specifications, inspections, and payment items in contracts. Given Data / Assumptions: Three-coat work over lath or masonry background. Standard lime–cement–sand mixes with appropriate curing. Coat thicknesses and timing follow trade practice. Concept / Approach: The scratch coat establishes a rough, keyed base and levels major irregularities; it is scratched to promote mechanical bond. The brown coat builds body and corrects plane, providing a smooth, plumb substrate. The white (finish) coat develops the final appearance and surface hardness, often with finer aggregates or neat materials. Correct curing between coats controls shrinkage cracking. Step-by-Step Solution: Identify first coat purpose: keying → “scratch coat”.Second coat purpose: build and true surface → “brown coat”.Third coat purpose: final finish → “white coat”.Thus, all three statements describing the coat names are correct. Verification / Alternative check: Trade manuals and codes list the same nomenclature, with recommended thicknesses such as roughly 10–12 mm scratch, 6–8 mm brown, and 3–4 mm finish, depending on system. Why Other Options Are Wrong: “None” contradicts established practice; single statements omit the complete sequence. Common Pitfalls: Applying coats too quickly without adequate set/cure; omitting scratches; finishing over a still-green brown coat leading to crazing. Final Answer: All of the above

Question 8

Flooring – What do you call a floor made with about 4–6 mm marble chips? Identify the correct term for a floor finish where marble chips of approximately 4–6 mm size are mixed with a binder, laid in situ or as tiles, and then ground and polished to …

Accepted Answer

Introduction / Context: Decorative hard floors are categorized by composition and installation method. When small marble chips are dispersed in a cementitious or resin matrix, laid, and subsequently ground and polished, the product is known as terrazzo. This finish has long service life and a characteristic speckled appearance determined by chip size and distribution. Given Data / Assumptions: Chip size about 4–6 mm with uniform distribution. Matrix is cement-based (traditional) or resin-based (modern). Finish is ground and polished after curing. Concept / Approach: Terrazzo is distinct from “marble slab floor”, which uses whole slabs, and from generic “mosaic floor”, which usually implies assembly of small tiles or tesserae into patterns rather than in-situ chip-and-binder composite. The term “reinforced marble floor” is not standard for this finish. Step-by-Step Solution: Identify material system: marble chips + binder → composite layer.Installation: laid, then machine-ground and polished → terrazzo process.Therefore, the correct term is “Terrazzo floor”. Verification / Alternative check: Specifications for terrazzo define chip grading (for example, fine, standard, Venetian) and binder ratios; BOQs call out chip size and thickness accordingly. Why Other Options Are Wrong: Marble slab floor refers to stone slabs; “chip floor” is informal; “mosaic” refers to patterned small tiles; “reinforced marble floor” is non-standard nomenclature. Common Pitfalls: Insufficient curing before grinding; poor chip dispersion leading to patchiness; not specifying divider strips for crack control. Final Answer: Terrazzo floor

Question 9

Building structural layout in multi-storey construction: Which of the following statements correctly describe how slabs, beams, and girders act together to transfer loads to columns?

Accepted Answer

Introduction / Context: Understanding the load path in a typical reinforced concrete frame is foundational for architects, engineers, and quantity surveyors. In multi-storey buildings, slabs, beams, girders, and columns act together to collect, distribute, and transfer gravity and lateral loads. This question checks whether you recognize the standard hierarchy used in most framed structures. Given Data / Assumptions: A conventional reinforced concrete (R.C.) framed building with slabs, secondary beams, main beams (girders), and columns. Monolithic casting is common for slab–beam systems. Secondary beams improve serviceability by reducing slab spans. Concept / Approach: In an R.C. frame, slabs collect distributed loads (self-weight, finishes, live loads). These slab loads are transferred to secondary beams, then to primary beams (girders), and finally to columns and foundations. Monolithic casting of slab and beams allows composite action, continuity, and integral behavior, reducing deflections and improving distribution. Beams are indeed the main flexural elements, while girders act as major framing lines supporting beams and concentrating loads into columns. Step-by-Step Solution: Recognize that slabs are cast together with supporting beams → monolithic action enhances strength and stiffness.Identify that beams (often resting on or framing into girders) are the main collectors to carry load to columns.Note that slabs typically span onto secondary beams which reduce slab panel spans and deflections.Therefore, all statements (a), (b), and (c) are correct; choose “All of these”. Verification / Alternative check: Standard design texts and codes show tributary load paths: slab → secondary beam → main beam/girder → column → foundation. Monolithic behavior is assumed in typical beam–slab design unless joints dictate otherwise. Why Other Options Are Wrong: Options that select only some statements ignore the complete, conventional load path and the common monolithic casting practice. Common Pitfalls: Confusing “girder” and “beam,” or assuming slabs always span directly to primary beams; neglecting the role of secondary beams in serviceability and economy. Final Answer: All of these.

Question 10

Damp-proof course (D.P.C.) best practice in building construction: Which statements are correct?

Accepted Answer

Introduction / Context: Damp-proof courses (D.P.C.) prevent capillary rise of moisture and lateral moisture ingress through walls and floors. A correct D.P.C. specification is crucial to avoid efflorescence, plaster failure, mold growth, and timber decay. This question reviews fundamental requirements applicable on site. Given Data / Assumptions: D.P.C. is a layer of impervious material installed at strategic levels in walls and floors. Materials may include polymer-modified asphaltic membranes, bitumen felt, dense cement mortar with admixtures, or polymer sheets. Continuity and proper lapping at intersections are essential. Concept / Approach: A D.P.C. must be continuous to be effective; any discontinuity permits moisture bypass. The material must be adequately impervious and durable. Depending on detail, a horizontal D.P.C. (e.g., above plinth) blocks rising damp, while vertical D.P.C. (or tanking) protects abutments, retaining walls, and areas exposed to lateral moisture. Proper interface details at junctions ensure that both orientations work together. Step-by-Step Solution: Check (a): continuity is mandatory to prevent moisture bridges → correct.Check (b): only impervious, durable materials can provide long-term damp-proofing → correct.Check (c): both horizontal and vertical applications exist and are often combined (e.g., floor-to-wall) → correct.Therefore, select “All the above”. Verification / Alternative check: Site manuals and codes emphasize continuous, well-lapped D.P.C. with compatible materials at junctions; failures typically trace back to discontinuities or unsuitable materials. Why Other Options Are Wrong: Limiting to only some statements ignores common, necessary practices such as vertical damp-proofing in splash or retaining conditions. Common Pitfalls: Interrupting D.P.C. at door thresholds, poor lapping at corners, or piercing the D.P.C. with fixings without proper sealing. Final Answer: All the above.

Question 11

Plaster defects: The local swelling (bulging) that appears on a finished plastered surface is termed

Accepted Answer

Introduction / Context: Diagnosing plaster defects helps in prescribing correct repairs and preventing recurrence. Different defects have distinct causes and visual signatures. The term for localized swellings or bubbles forming after finishing is essential vocabulary for site supervision. Given Data / Assumptions: A finished plaster surface shows small bulges or raised patches. Defects may arise from workmanship, materials, or substrate conditions. We distinguish between cracks, blisters, crazing, and other issues. Concept / Approach: “Blistering” describes the local swelling of plaster, often caused by improper troweling during setting, trapped air, over-rich fat lime, contamination, or lack of suction control on very smooth backgrounds. In contrast, “cracking” is the formation of fractures due to shrinkage or movement; “crazing” is a network of fine hairline cracks; “dubbing” is leveling out irregularities before final plaster; “hacking” is roughening the background to improve bond. Step-by-Step Solution: Identify the symptom: localized bulges or bubbles after finishing → blistering.Eliminate other terms: cracking (fractures), crazing (mesh of fine cracks), dubbing (pre-leveling), hacking (surface preparation).Therefore, the correct term is “Blistering”. Verification / Alternative check: Repair guides recommend cutting out blisters back to sound substrate, re-keying, and refilling with suitable plaster, confirming that the phenomenon is distinct from cracking or crazing. Why Other Options Are Wrong: Cracking/Crazing refer to fissures, not swellings.Dubbing is a preparatory operation, not a defect.Hacking is a roughening process, not a finished-surface issue. Common Pitfalls: Over-troweling or polishing too early; inadequate suction control; using contaminated water or salts that cause surface reactions. Final Answer: Blistering.

Question 12

Masonry arches: The voussoir placed at the crown (midpoint at the top) of an arch is known as the

Accepted Answer

Introduction / Context: Arches are built from wedge-shaped blocks called voussoirs. Certain voussoirs have special names because of their structural role. Recognizing the “keystone” at the crown is vital for reading details and understanding load transfer in traditional masonry. Given Data / Assumptions: An arch of wedge-shaped stones or bricks (voussoirs). The uppermost central voussoir at the crown is being identified. Standard arch terminology applies. Concept / Approach: The “keystone” is the crown voussoir that effectively locks the arch ring in place when centering is removed. The “springers” are the lowest voussoirs at the springing points; the “soffit” is the intrados surface (underside) of the arch; the “haunch” refers to the region between crown and springing, not a single block. Step-by-Step Solution: Identify the topmost central block → keystone.Exclude soffit (a surface), springer (lowest voussoir), and haunch (a region).Therefore choose “Key (keystone)”. Verification / Alternative check: Historic masonry references and drawings label the crown voussoir as the keystone, often sculpted decoratively in classical architecture. Why Other Options Are Wrong: Soffit: not a voussoir; it is the inner curved surface.Springer: located at the base, not the crown.Haunch: zone of the arch, not a particular block. Common Pitfalls: Confusing a geometric region name with the name of a voussoir; misplacing springers and keystone. Final Answer: Key (keystone).

Question 13

Pile classification: A pile that primarily carries load through friction between its surface and the surrounding soil is called a

Accepted Answer

Introduction / Context: Piles transfer structural loads to the ground through tip (end) bearing, shaft friction, or a combination. Correct terminology is essential for design and construction communication, especially when interpreting soil investigation reports and capacity calculations. Given Data / Assumptions: The pile derives most of its capacity from interface resistance along the shaft. Soil may be clayey, sandy, or mixed; friction mobilization depends on effective stress and roughness. Tip resistance is not the dominant component. Concept / Approach: A “friction pile” (also called a skin-friction pile) gains capacity from the adhesion and friction developed along its surface. In contrast, an “end-bearing pile” or “bearing pile” is seated on a dense or strong stratum, and a “sheet pile” is a thin wall element used for earth retention and cutoff. “Battered piles” are inclined piles used to resist horizontal loads, regardless of whether capacity is frictional or end bearing. Step-by-Step Solution: Match the load transfer mechanism (shaft friction) to the name → “Friction pile”.Differentiate from bearing piles (tip-controlled) and sheet piles (retaining function).Select the correct term. Verification / Alternative check: Design formulas split capacity into Q_s (shaft) and Q_b (base). For friction piles, Q_s is the governing component. Why Other Options Are Wrong: Bearing pile/end-bearing pile: governed by tip resistance, not shaft friction.Sheet pile: not a foundation pile for vertical loads.Battered pile: an inclination descriptor, not a load-transfer mechanism. Common Pitfalls: Assuming all piles are end-bearing; ignoring that long piles in soft strata can still carry significant load via skin friction. Final Answer: Friction pile.

Question 14

Minimum wall thickness for single-storey loadbearing walls built in cement mortar 1:6 (cement:sand) – what is the recommended minimum?

Accepted Answer

Introduction / Context: For loadbearing masonry in small buildings, minimum wall thickness ensures adequate compressive capacity, lateral stability, and robustness under openings and eccentricities. The mortar grade and wall height influence practical minimums used in byelaws and schedules of rates. Given Data / Assumptions: Single-storey building. Masonry in cement mortar 1:6 (cement:sand) using standard bricks or blocks. Typical room heights and common live loads. Concept / Approach: Traditional practice adopts one-brick (approximately 20 cm) minimum thickness for external loadbearing walls in single-storey buildings to control slenderness and provide stability during out-of-plane wind suction. Thinner walls (10–15 cm) are often used as non-loadbearing partitions or with reinforced bands and stiffeners; thicker walls (25–30 cm) are reserved for higher loads or multi-storey construction. Step-by-Step Solution: Check slenderness: thinner walls reduce buckling resistance and increase damage risk.Consider mortar grade 1:6: adequate for one-brick walls under typical loads in single-storey buildings.Select the commonly recommended minimum: 20 cm. Verification / Alternative check: Many public works schedules and building byelaws cite about 20 cm as the minimum for external loadbearing walls at single-storey height where no special reinforcement is provided. Why Other Options Are Wrong: 10–15 cm: generally used for partitions or non-loadbearing infill; too slender for primary loadbearing without special measures.25–30 cm: safe but not the minimum; increases cost and plan area. Common Pitfalls: Confusing non-loadbearing partitions with loadbearing walls; ignoring lateral stability and impact resistance around openings. Final Answer: 20 cm.

Question 15

Brick corbels: Which of the following statements is NOT correct for the design and construction of brick corbels?

Accepted Answer

Introduction / Context: A brick corbel is a stepped projection formed by successive courses, used to support beams, projections, or decorative features. Safe proportioning and correct bonding are essential to avoid shear failure at the offsets and to ensure durability under service loads. Given Data / Assumptions: Corbels are constructed by stepped projections of masonry courses. Wall thickness limits the safe total projection. Per-course projection limits help maintain stability and bond. Concept / Approach: Good practice limits the total projection to not more than the supporting wall thickness and keeps each step modest (about one-quarter brick) to maintain bonding and shear resistance. For heavy concentrated loads, continuous, well-bonded corbels or alternative structural supports (e.g., reinforced concrete brackets, steel shelves) are preferred; discontinuous corbels provide poor load sharing and stress concentrations. Step-by-Step Solution: Evaluate (a): widely accepted limit; helps avoid overstressing → correct.Evaluate (b): limiting per-course projection improves stability → correct.Evaluate (c): recommending discontinuous corbels for heavy concentrated loads is unsafe → NOT correct.Evaluate (d): stretcher-bond layouts are common where units are stepped; headers may be introduced per detail; statement is generally acceptable.Therefore, (c) is the incorrect activity. Verification / Alternative check: Construction handbooks caution against excessive offset and emphasize continuous, well-bonded arrangements for significant loads; discontinuous projections should be avoided for heavy point loads. Why Other Options Are Wrong: (a) and (b) reflect standard proportioning limits.(d) and (e) describe common bonding and jointing practices to enhance performance. Common Pitfalls: Over-projecting per course; poor bonding at offsets; attempting to support heavy beams on isolated corbel blocks without proper continuity or reinforcement. Final Answer: Discontinuous (separate) corbels are preferred for carrying heavy concentrated loads is NOT correct.

Question 16

Geotechnical site exploration guideline: As a rule of thumb, the minimum depth of exploration recommended for each storey of a building is

Accepted Answer

Introduction / Context: Determining an adequate depth of geotechnical exploration helps identify soil layering, groundwater conditions, and potential weak strata influencing settlement. While rigorous criteria use stress bulbs and percentage stress increase, rules of thumb are commonly referenced at the planning stage. Given Data / Assumptions: Low- to mid-rise building with conventional spread footings or raft. Preliminary planning stage (before detailed foundation modeling). Uniform soil profile is not guaranteed; exploration should capture critical layers. Concept / Approach: A practical guideline is to explore to at least about 2 metres per storey, subject to a minimum depth sufficient to intercept any compressible layer that could influence total or differential settlement. In detailed design, depth should extend where the net foundation pressure causes less than about 10% stress increase, or until a firm stratum is confirmed, whichever is deeper. The rule of 2 m per storey provides an initial planning benchmark for borehole depth scheduling. Step-by-Step Solution: Adopt the planning rule: ~2 m per storey.Cross-check with structural loads and expected foundation type to adjust as necessary.Ensure the exploration captures soft layers or perched water tables affecting settlement.Select “2 metres” as the thumb-rule answer. Verification / Alternative check: Many practice guides suggest 1.5–3.0 m per storey, with 2 m a balanced nominal figure; final depths are refined using stress distribution analysis (e.g., influence charts) and field observations. Why Other Options Are Wrong: 1 m: Often insufficient to capture influence depth for storey loads.3–4 m: May be conservative or uneconomical at planning stage without specific triggers.0.5 m: Clearly inadequate for foundation decisions. Common Pitfalls: Using the rule blindly without checking stress bulbs; stopping before encountering a compressible layer that later governs settlements. Final Answer: 2 metres.

Question 17

Plastering and brickwork pathologies: Which of the following statements are correct?

Accepted Answer

Introduction / Context: Post-construction surface defects are common in masonry and plaster finishes. Recognizing typical symptoms and remedies allows effective maintenance and avoids misdiagnosis that can lead to inappropriate repairs. Given Data / Assumptions: Plastered masonry walls with normal environmental exposure. Efflorescence arises from soluble salts migrating to the surface. Thermal and moisture movements can induce cracking or debonding. Concept / Approach: Hair cracks (crazing or fine shrinkage cracks) are frequently observed due to drying shrinkage, inadequate curing, or minor substrate movement. Efflorescence results from evaporation leaving salt crystals; mild efflorescence may be treated with brushing and solutions like zinc sulphate to neutralize and remove deposits. Large thermal gradients can cause differential movement between plaster and backing, weakening the bond and leading to drumming or fall-off. Step-by-Step Solution: Assess (a): hairline cracks on plaster → common and well-documented.Assess (b): zinc sulphate solution is a known treatment to help remove efflorescence and reduce reappearance.Assess (c): excessive thermal variation causes expansion/contraction mismatch → potential debonding and failure.Therefore choose “All of the above”. Verification / Alternative check: Maintenance manuals recommend mechanical removal plus chemical washes for efflorescence, and control joints/cures for shrinkage cracking; thermal protection and shading reduce debonding risks. Why Other Options Are Wrong: Selecting only some statements ignores well-known causes and remedies in building pathology. Common Pitfalls: Painting over efflorescence without removal; neglecting curing; omitting movement joints or thermal considerations in exposed walls. Final Answer: All of the above.

Question 18

Residential stair design: What is the recommended minimum clear width of a stair in typical residential buildings?

Accepted Answer

Introduction / Context: Stair width affects usability, safety, and evacuation. Residential requirements are less onerous than public buildings, but minimum widths should still allow comfortable and safe passage for occupants carrying items such as laundry or furniture. Given Data / Assumptions: Typical single-family or small residential building. Local byelaws vary, but common practice provides a baseline. Clear width is measured between finished faces of handrails/walls. Concept / Approach: Many residential standards adopt a practical minimum near 0.85–0.90 m for main stairs, balancing circulation comfort and plan economy. Wider stairs are encouraged for duplexes or frequent furniture movement, whereas public buildings typically require ≥1.0 m to 1.2 m or more depending on occupancy. For tight plans, 0.85 m is a sensible lower limit to avoid awkward passing and to accommodate hand clearance. Step-by-Step Solution: Identify the building type: residential (not assembly or institutional).Apply common practice minimum width for residential stairs.Among choices, 85 cm matches typical lower bound; narrower widths (55–70 cm) are impractical and unsafe.Select 85 cm as the recommended minimum. Verification / Alternative check: Several handbooks recommend 0.85–0.90 m minimum for residential stairs, with 1.0 m or more preferred for comfort. Why Other Options Are Wrong: 55 cm, 70 cm: Too narrow for safe two-way maneuvering and moving objects.100 cm, 120 cm: Acceptable or preferred, but not the minimum in small residences. Common Pitfalls: Ignoring handrail intrusions into clear width; locating switches, risers, or nosings that reduce usable width at turns or winders. Final Answer: 85 cm.

Question 19

Subsurface investigation — when is the auger boring method unsuitable? Auger boring (hand or portable power augers) is commonly used in cohesive, self-supporting soils above the water table. In which of the following ground conditions is auger borin…

Accepted Answer

Introduction / Context: Auger boring is a simple and economical exploration method for shallow depths. However, it relies on the surrounding soil remaining stable (self-supporting) and on the auger cutting efficiently. Recognizing when auger boring becomes unsafe or ineffective helps you select better alternatives (cased borings, wash boring, rotary, percussion). Given Data / Assumptions: Hand or portable power helical augers. No casing or drilling mud for wall support unless noted. Objective is to advance the hole safely while obtaining representative information. Concept / Approach: Augers work best in cohesive or otherwise self-supporting soils above the water table. In very hard/cemented layers the bit cannot cut effectively; in fully saturated cohesionless soils the walls slough and the hole collapses without casing; in very soft soils there is insufficient stand-up time and excessive squeezing into the auger flights, leading to unsafe and poor-quality holes. Step-by-Step Solution: Check very hard/cemented strata → resistant to cutting → progress is poor and tools may be damaged.Check fully saturated sands → no cohesion → immediate collapse without casing → unsafe and unreliable.Check very soft soils → lack of stand-up time → sidewall squeezing and collapse.Therefore all listed cases are unsuitable → choose “All of the above”. Verification / Alternative check: Most geotechnical manuals recommend casing or switching to wash/rotary or percussion in saturated sands and to percussion/rotary coring for very hard or cemented layers; hand augers are explicitly limited to shallow, self-supporting soils above the water table. Why Other Options Are Wrong: (a), (b), (c) individually identify true limitations, but each alone is incomplete. (e) “None” is incorrect because several unsuitable cases exist. Common Pitfalls: Attempting to auger below the water table in sand without casing and expecting stable holes. Assuming the presence of silt gives cohesion; saturated silty sand may still collapse. Final Answer: All of the above.

Question 20

Pre-stressed concrete piles — key advantages in handling, durability, and load capacity Which statement best summarizes the practical benefits of using pre-stressed concrete piles for foundations and marine works?

Accepted Answer

Introduction / Context: Pre-stressed concrete (PSC) piles are widely used in bridges, jetties, and building foundations. Precompression improves service performance, while factory-controlled production ensures quality and durability. This question tests your understanding of the combined advantages that make PSC piles popular in practice. Given Data / Assumptions: Factory-cast pre-tensioned or post-tensioned concrete piles. Appropriate concrete cover, mix, and prestressing level. Design considers handling, driving, and in-service loads. Concept / Approach: Prestressing introduces a compressive force that offsets tensile stresses from bending during lifting, driving, and service. This minimizes cracking, enhancing durability (especially in marine or aggressive environments). With optimized cross-sections and higher material efficiency, PSC piles can deliver high capacities with lower self-weight relative to comparable non-prestressed RC sections. Step-by-Step Solution: Handling: precompression reduces tensile stress during lifting and driving → fewer cracks → easier handling.Self-weight vs. capacity: material efficiency allows smaller sections → lighter for a given capacity.Durability: crack control and quality production improve long-term performance.Load capacity: high-strength strands plus confinement provide excellent axial and bending resistance. Verification / Alternative check: Design guides show superior allowable driving stresses and higher moment capacities for PSC piles compared to mild-steel-reinforced RC piles of similar dimensions. Why Other Options Are Wrong: Options (a)–(d) are each correct; the comprehensive answer is (e). Common Pitfalls: Ignoring handling and driving stresses in strand layout, leading to cracks despite prestress. Underestimating corrosion risks in cut-off zones; proper detailing is still required. Final Answer: All of the above.

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