Question 1

Door selection by function: match typical door types to suitable locations (louvered, flush, revolving, sliding) and identify the correct comprehensive statement.

Accepted Answer

Introduction / Context: Different door types address ventilation, privacy, traffic management, and space efficiency. Understanding where each type is typically used supports practical design and specification decisions. Given Data / Assumptions: Louvered doors provide air movement while maintaining privacy. Flush doors are simple, cost-effective interior doors. Revolving doors manage large crowds and reduce air infiltration. Sliding doors minimize swing clearance and suit display areas. Concept / Approach: Louvered doors are common in bathrooms/W.C. for ventilation. Flush doors are flat-faced doors widely used in living/dining/bedrooms. Revolving doors appear at theaters/cinemas/malls for crowd flow control and energy savings. Sliding doors are used in showrooms and shops for ease of access and maximum display frontage. Step-by-Step Solution: Map each door type to its typical location and function.All listed mappings are standard and appropriate.Therefore choose “All of the above.” Verification / Alternative check: Architectural standards and building guides place these door types as described for function and traffic needs. Why Other Options Are Wrong: Choosing a single statement omits other equally correct and common uses. Common Pitfalls: Using louvered doors where sound/privacy control is paramount; specifying revolving doors without considering accessibility requirements. Final Answer: All of the above

Question 2

In traditional roof and truss construction, the projecting structural piece provided to support a truss at the wall junction is commonly known as what?

Accepted Answer

Introduction / Context: In masonry and timber roof construction, trusses require intermediate bearing or support where they rest on walls or columns. A projecting piece that extends out of the wall face to carry load is traditionally called a corbel. Recognizing the distinction between decorative elements and load-bearing projections is key in building terminology. Given Data / Assumptions: The question refers to a projecting structural member, not merely decorative moldings. The function is specifically to support a truss (a roof framework component). Common architectural elements like cornice, coping, frieze, and lintel have different purposes. Concept / Approach: A corbel is a masonry projection from a wall face that acts as a bracket to support loads such as trusses, beams, balconies, or arches. It transfers load back into the wall. This is distinct from cornice (decorative molding at roofline), coping (protective cap of a wall), frieze (decorative horizontal band), or lintel (beam across openings). Step-by-Step Solution: Identify requirement: load-bearing projection for truss.Match to correct terminology: corbel is the element that projects to support loads.Other listed terms are decorative or serve different functions.Therefore, the correct answer is corbel. Verification / Alternative check: Architectural references in construction handbooks define corbel as a structural masonry bracket, distinct from decorative cornices and friezes. Why Other Options Are Wrong: Cornice: decorative projection, not load-bearing for trusses. Coping: top protective covering of walls against rain. Frieze: horizontal decorative band between cornice and architrave. Lintel: horizontal beam over openings like doors and windows; not projecting support for trusses. Common Pitfalls: Confusing lintel (structural but horizontal above openings) with corbel; misusing decorative terms for structural support elements. Final Answer: Corbel

Question 3

Foundation design for boundary walls: to keep the soil reaction on an offset footing fully compressive (no tension anywhere), where should the resultant line of action or C.G. of the applied load fall on the base?

Accepted Answer

Introduction / Context: For masonry boundary walls on offset or eccentric footings, avoiding tensile contact stress under the base is essential. Classical foundation theory uses the middle-third rule to ensure a linear, fully compressive pressure distribution and to prevent uplift or cracking at the heel or toe. Given Data / Assumptions: Rigid footing on a linear-elastic soil idealization with resultant load acting at some eccentricity e from the centroid. Pressure distribution under the base remains linear (no soil tension allowed). We seek the condition on the load's line of action (C.G.). Concept / Approach: For a rectangular base of breadth B with an applied vertical load W at eccentricity e, the contact pressure varies linearly. If e ≤ B/6 (i.e., resultant lies within the middle third), the pressure at both edges remains nonnegative. If e > B/6, tensile stress appears at one edge, violating the “fully compressive” requirement. Step-by-Step Solution: Define middle-third range: centroidal zone bounded by ±B/6 about the geometric centre.Require zero tension: enforce e ≤ B/6 so p_min ≥ 0.Therefore, the C.G. must fall within the middle third of the base. Verification / Alternative check: Using the linear pressure formula p(x) = W/B ± 6W e/(B^2) at edges shows p_min ≥ 0 only if e ≤ B/6, directly giving the middle-third rule. Why Other Options Are Wrong: At the centre: sufficient but not necessary; the whole middle third is acceptable. Middle fifth: overly restrictive and not required by theory. Neither: contradicts the established middle-third criterion. Common Pitfalls: Confusing serviceability limits (tilt) with strength/pressure limits (tension avoidance). Final Answer: within the middle third of the base

Question 4

Raft foundation detailing: by how much is a raft (mat) slab usually projected beyond the outer face of the external walls for cover, protection, and construction tolerance?

Accepted Answer

Introduction / Context: Raft (mat) foundations distribute loads over a large plan area. A modest projection beyond the wall face is customary to ensure proper cover, shuttering, edge protection against spalling, and tolerance during construction. Given Data / Assumptions: Typical building raft supporting walls and columns. Conventional reinforced concrete detailing and site practices. We seek a standard practical projection range. Concept / Approach: A projection of about 0.25 m to 0.30 m allows adequate edge cover, room for shear keys or starter bars near the face, and manageable formwork. Smaller projections (5–10 cm) are impractical; larger ones (≥0.45 m) may be used in special cases but are not typical for ordinary walls. Step-by-Step Solution: Match common detailing practice: select 25–30 cm.Confirm constructability: supports adequate edge cover and shuttering.Hence, choose 25 to 30 cm as the standard range. Verification / Alternative check: Standard detailing guides and BOQs often specify 250–300 mm overhang from the external wall face for rafts, barring site-specific constraints. Why Other Options Are Wrong: 5–10 cm: insufficient tolerance/cover. 15–20 cm: lean for edges and tolerance. 30–45 cm or 60 cm: possible but not “usual,” increases concrete usage without need. Common Pitfalls: Ignoring waterproofing terminations which also need space at slab edges. Final Answer: 25 to 30 cm

Question 5

Concrete construction: the soffit (underside) formwork of slabs may be removed only after approximately how many days under normal conditions?

Accepted Answer

Introduction / Context: Formwork removal timing balances construction speed with safety and performance. The soffit of slabs supports self-weight and early-age loads; removing it too soon risks deflection and cracking. Given Data / Assumptions: Ordinary Portland cement, typical ambient temperatures. Sound curing practices; props may remain per code if needed. Question focuses on usual benchmark times, not special concretes. Concept / Approach: Industry practice sets minimum periods before stripping based on member type. For slabs, side forms may go earlier, but the soffit formwork generally remains about 7 days under normal conditions to ensure adequate strength and stiffness. Beams/girders require longer or continued propping. Step-by-Step Solution: Identify member: slab soffit → medium stripping time.Select common benchmark: approximately 7 days. Verification / Alternative check: Many code tables and handbooks cite ~7 days for slab soffits at normal temperatures, with adjustments for rapid hardening cement or cold weather. Why Other Options Are Wrong: 1 or 4 days: too early for most slabs; risk of deflection. 14 days: conservative but not typically required for slabs (more for beams/props retention). Common Pitfalls: Confusing side-form removal (early) with soffit removal (later). Final Answer: 7 days

Question 6

Mortars and concretes in building works: identify the incorrect statement among the following common site practices and material properties.

Accepted Answer

Introduction / Context: Selecting proper binders and mixes for masonry, plaster, and concrete is a core site skill. Some statements are true generalizations; others conflict with standard practice. This item asks you to find the incorrect one. Given Data / Assumptions: Lime mortars (fat/hydraulic), surkhi (brick powder) as pozzolanic additive. Pointing is typically a hard, weather-resistant finish. Cold-weather concreting favors faster strength gain. Concept / Approach: Good practice requires slaking lime prior to mortar preparation for uniformity and workability. Adding cement to lime mortar yields cement–lime mortar with increased hydraulic set and strength. In cold weather, high early strength concrete/cement helps reach target strengths sooner. Conversely, lime–surkhi mortar is more suited for general masonry/plaster; pointing usually uses stronger cement mortar for weathering resistance, not lime–surkhi. Step-by-Step Solution: Validate each statement against common practice.Identify that “Lime surkhi mortar is used for pointing the walls” is atypical/incorrect.Select this as the incorrect option. Verification / Alternative check: Measurement and specification handbooks list cement mortar (e.g., 1:3 or 1:4) for pointing; lime–surkhi rarely meets durability expectations for exposed pointing. Why Other Options Are Wrong: (a) Correct: slaking is essential. (b) Correct: accelerates strength gain in cold weather practices. (c) Correct: cement addition improves hydraulic properties and strength. Common Pitfalls: Assuming any mortar suits pointing; exposure demands strong, dense mixes. Final Answer: Lime surkhi mortar is used for pointing the walls

Question 7

Percussion drilling in geotechnical exploration: which of the following drawbacks can occur during boring and observation?

Accepted Answer

Introduction / Context: Percussion (shell and auger) drilling remains popular for economical site investigation. However, its dynamic, slurry-assisted cutting can compromise stratigraphic clarity and groundwater readings compared to more controlled methods. Given Data / Assumptions: Percussion action with bailer/shell; water or slurry may be used. Soils may be soft or cohesionless, prone to caving. Groundwater level monitoring desired. Concept / Approach: Impact energy and circulation can cause wall sloughing and mixing of materials, especially in sands/silts. Slurry penetration below the hole bottom can mask true groundwater conditions. Repeated impacts disturb the soil fabric beyond the immediate cutting face, affecting sampling representativeness. Step-by-Step Solution: List known drawbacks: caving/mixing, groundwater masking, deeper disturbance.All listed drawbacks are recognized for percussion drilling.Therefore, select “all the above.” Verification / Alternative check: Comparative studies note better groundwater and undisturbed sampling from rotary wash with casing or rotary coring than from percussion methods. Why Other Options Are Wrong: Choosing any single effect understates the cumulative drawbacks. Common Pitfalls: Relying on percussion logs for fine stratigraphy without corroborating SPT/undisturbed samples. Final Answer: all the above

Question 8

Earth pressure (Rankine active): if φ is the angle of repose (internal friction angle) and the soil unit weight is w (kg/m^3), what is the horizontal pressure intensity p at depth h per metre length of a vertical wall (level backfill)?

Accepted Answer

Introduction / Context: Estimating lateral earth pressure is fundamental for retaining wall and sheet pile design. For level backfill and wall yielding sufficiently, Rankine’s active state is a standard starting point. Given Data / Assumptions: Homogeneous dry backfill; unit weight w (kg/m^3). Internal friction angle φ; wall face vertical; backfill horizontal. Wall yields enough to mobilize active condition; cohesionless case for simplicity. Concept / Approach: Rankine's active earth pressure coefficient is K_a = (1 - sin φ)/(1 + sin φ) = tan^2(45° - φ/2). The lateral pressure intensity at depth h is p = K_a * w * h (using consistent units; convert if using specific weight). Either expression for K_a is acceptable; the tan-form is often memorized. Step-by-Step Solution: Compute K_a = tan^2(45° - φ/2).Then p(h) = K_a * w * h.Hence p = w * h * tan^2(45° - φ/2). Verification / Alternative check: Using the sine form: K_a = (1 - sin φ)/(1 + sin φ). Multiplying by w*h gives the same p, confirming equivalence. Why Other Options Are Wrong: tan^2(45° + φ/2) and (1 + sin φ)/(1 - sin φ) correspond to K_p (passive), not active. Option (d) gives K_a but not in the tan^2 form asked; since multiple correct forms confuse MCQs, the canonical tan^2(45° - φ/2) is the keyed answer here. Common Pitfalls: Interchanging active/passive signs or using γ instead of w inconsistently; ensure unit consistency. Final Answer: p = w * h * tan^2(45° - φ/2)

Question 9

Dewatering practice: a single-stage well-point system can effectively lower groundwater and dewater an excavation down to approximately what maximum depth?

Accepted Answer

Introduction / Context: Well-point systems are widely used for lowering groundwater around shallow excavations. The achievable drawdown in a single lift is limited by suction and pump performance. Given Data / Assumptions: Conventional single-stage well points connected to a header and a vacuum-assisted pump. Permeable soils where well points are effective. We seek the practical maximum depth of effective drawdown per stage. Concept / Approach: Atmospheric pressure limits suction lifts to roughly 7–8 m under ideal conditions. Accounting for losses and field reality, the practical drawdown per stage is typically about 4.5–5.5 m. Hence, a single-stage system is generally capped at about 5 m. Deeper excavations require multi-stage well points or deep wells. Step-by-Step Solution: Relate suction limit to groundwater drawdown capability.Apply field allowances: adopt ≈ 5 m for a single stage. Verification / Alternative check: Manufacturers’ data and method statements frequently recommend further stages for depths exceeding ~5 m. Why Other Options Are Wrong: 10–25 m: exceed practical single-stage limits; would require deep wells or staged systems. 15–20 m: similarly unrealistic for single-stage well points. Common Pitfalls: Confusing deep well pumping (submersible pumps) with vacuum well points. Final Answer: 5 m

Question 10

Construction sequence for a raft foundation: arrange the following activities in correct order — (1) ramming foundation bed, (2) excavation to required depth, (3) laying reinforcement, (4) curing the concrete, (5) pouring concrete over reinforcement.

Accepted Answer

Introduction / Context: Correct sequencing in raft construction ensures dimensional control, reinforcement integrity, and concrete quality. Misordered steps can compromise bearing and durability. Given Data / Assumptions: (1) Ramming/compacting bed, (2) Excavation, (3) Reinforcement placement, (4) Curing, (5) Concreting. Conventional in-situ raft with blinding as needed. Concept / Approach: First excavate to formation level; prepare the founding bed by ramming/compaction (and blinding if specified). Then fix reinforcement, followed by placing concrete. Finally, curing is done to ensure hydration and durability. Step-by-Step Solution: Start with (2) Excavation to required depth.Then (1) Ram/prepare the foundation bed (and blinding).Next (3) Lay reinforcement as per bar schedule.Proceed to (5) Pour concrete over reinforcement.Finish with (4) Curing of the concrete. Verification / Alternative check: Method statements for raft pours follow this order; any deviation (e.g., reinforcing before bed preparation) is impractical. Why Other Options Are Wrong: They either place reinforcement or concrete before bed preparation or omit curing until the end. Common Pitfalls: Neglecting blinding or surface preparation before fixing rebar, leading to contamination or cover issues. Final Answer: 2, 1, 3, 5, 4

Question 11

Roof truss selection for factory spans of 6 m to 9 m: Which truss type is most appropriate to design and supervise?

Accepted Answer

Introduction / Context: Choosing a roof truss depends on span, loading, roof form, and economy. Traditional timber and steel trusses have practical span ranges beyond which alternative forms become more efficient. This question focuses on common light industrial spans of 6 m to 9 m. Given Data / Assumptions: Factory roof spans between 6 m and 9 m. Conventional symmetrical truss forms considered. Standard practice span ranges guide selection. Concept / Approach: King-post trusses are most economical for short spans (about 5 m to 8 m). Queen-post trusses economically cover medium spans (about 8 m to 12 m, often quoted 7 m to 10 m). For 6 m to 9 m spans, the range overlaps, but a queen-post truss offers greater headroom and better economy as the span approaches 9 m, while still being efficient at the lower end of the range when future load or roof slope considerations apply. Step-by-Step Solution: Identify the target span band: 6–9 m.Recall typical span suitability: King-post ~5–8 m; Queen-post ~8–12 m.For a span band that extends up to 9 m, prefer the truss that comfortably covers the upper limit (queen-post).Select queen-post truss as the appropriate choice. Verification / Alternative check: Design handbooks and building practice commonly recommend queen-post for spans near 9–10 m; king-post becomes material-inefficient as span increases toward 9 m under industrial loads. Why Other Options Are Wrong: Mansard truss: Specialized broken-pitch roof form, not chosen primarily for this span band.King-post truss: Better for shorter spans; may be marginal at 9 m.Collar truss: Typically for steep-pitched roofs and shorter spans in domestic settings.None of these: Incorrect because queen-post is suitable. Common Pitfalls: Assuming the smallest truss that can span is best; economy and deflection often favor the next truss type as span approaches the upper end of a range. Final Answer: Queen-post truss.

Question 12

Ground improvement — definition and use of “sand piles” (civil engineering foundation practice) Pick the correct statement about sand piles used for densification/improvement of loose granular soils beneath foundations. Choose the description that b…

Accepted Answer

Introduction / Context: In foundation engineering, “sand piles” (also called sand compaction piles) are a classic ground-improvement technique for loose granular or soft cohesive soils. Rather than acting as conventional load-bearing piles, they densify the surrounding soil, reduce compressibility, and improve bearing capacity indirectly. This question checks whether you recognize the correct definition and typical role of sand piles in practice. Given Data / Assumptions: We are considering improvement methods for weak ground under shallow or raft foundations. Sand piles are installed by driving a casing or augering, then backfilling with sand in stages and compacting. The primary intent is densification and drainage, not direct end-bearing like concrete or steel piles. Concept / Approach: Sand piles are constructed by forming a hole (with casing/auger/vibroflot), then filling with granular material (clean sand) in lifts with compaction. The sand column stiffens the composite soil mass and accelerates consolidation if soft fines are present. The system is analogous to stone columns but with sand as the column material. Load transfer is shared between improved soil and the sand columns; the improvement is often specified by replacement ratio and achieved relative density. Step-by-Step Solution: Identify what a “sand pile” is: a formed hole filled with compacted sand → matches option (b).Contrast with option (a): merely driving a pile into a sand deposit does not define a sand pile.Assess purpose: sand piles mainly improve soil properties; they are not primarily designed as structural bearing piles → option (c) is incorrect.Therefore, the correct statement is option (b). Verification / Alternative check: Field practice (e.g., vibro-replacement with sand) increases SPT N-values, decreases settlement, and mitigates liquefaction susceptibility. Settlement records and plate load tests post-improvement substantiate the function as ground improvement rather than pure end-bearing action. Why Other Options Are Wrong: (a) Mislabels any pile driven in sand as a “sand pile”, which is incorrect terminology. (c) Overstates the role; sand piles do not typically act as high-capacity structural piles. (d) Incorrect because (b) is correct. Common Pitfalls: Confusing sand piles with cast-in-situ concrete piles or stone columns. Assuming capacity comes solely from the column; the composite action with surrounding soil is key. Final Answer: A drilled or driven hole that is then filled and compacted with clean sand is called a sand pile.

Question 13

Building repairs — what is the term for supporting an existing structure by adding supports beneath it? Identify the correct name for the technique of giving additional support to an existing building or structural element by introducing new support…

Accepted Answer

Introduction / Context: During renovations, foundation settlement remediation, or when adjacent excavations threaten stability, engineers may need to support an existing structure. Different techniques exist, and it is crucial to use the correct terminology to communicate scope and method in drawings, specifications, and permits. Given Data / Assumptions: Existing structure requires additional support beneath existing foundations. Goal is to transfer loads to deeper or stronger strata or to widen the bearing area. Temporary vs. permanent support distinctions are relevant. Concept / Approach: Underpinning specifically refers to introducing new supports below the existing foundation level to strengthen or stabilize the structure. Approaches include pit underpinning, mini-pile underpinning, beam-and-base, and resin injection methods. Shoring, by contrast, braces walls laterally (e.g., against earth pressure) and is usually temporary. Jacking is an action (lifting with jacks), not the overall technique. Piling forms deep foundations for new construction or as part of underpinning but is not itself the name of the remedial scheme in general context. Step-by-Step Solution: Determine whether support is beneath the foundation → yes.Match terminology: beneath-foundation strengthening → underpinning.Rule out lateral support (shoring) and simple lifting action (jacking).Conclude the correct term is “Underpinning”. Verification / Alternative check: Standard building codes and repair manuals categorize underpinning separately from shoring; method statements for underpinning include excavation in short lengths, sequencing, and monitoring for settlement/tilt. Why Other Options Are Wrong: (a) Shoring provides lateral/temporary support, not new foundation support. (c) Jacking is a lifting operation, often used within underpinning but not the method name. (d) Piling is a foundation type; without context it is not synonymous with underpinning. Common Pitfalls: Using “shoring” and “underpinning” interchangeably in BOQs can cause scope errors. Ignoring staged excavation and load transfer sequencing can endanger stability. Final Answer: Underpinning.

Question 14

Brickwork terminology — name of the 19 cm × 9 cm face seen on a wall elevation In standard modular brickwork, the long rectangular face measuring approximately 19 cm × 9 cm that appears on the wall face is called what?

Accepted Answer

Introduction / Context: Correct terminology in brick masonry is essential for specifying bond patterns (stretcher, header, English, Flemish), measuring quantities, and communicating details on site. Bricks are laid so that either their long face (stretcher) or short face (header) appears on the wall surface depending on the bonding pattern used. Given Data / Assumptions: Nominal brick size around 19 cm × 9 cm × 9 cm (without mortar). Question refers to the face as seen on the wall elevation. Standard nomenclature is assumed. Concept / Approach: A brick has three principal faces: stretcher face (long), header face (short), and bed face. When the long rectangular face is exposed on the wall surface, the unit is said to be laid as a stretcher. When the short face is exposed, it is a header. These definitions underlie the names of bonds and affect overlapping rules for structural integrity and aesthetics. Step-by-Step Solution: Identify the visible face dimensions: approximately 19 cm × 9 cm → long face.Match terminology: long exposed face = stretcher.Confirm that header face would show 9 cm × 9 cm square on the wall surface.Therefore the correct term is “Stretcher”. Verification / Alternative check: Bond diagrams in masonry handbooks depict stretchers as long faces in elevation; site practice uses terms consistently for setting out and measurement. Why Other Options Are Wrong: (d) Header is the short face exposed, not 19 cm × 9 cm. (b), (c), (e) are non-technical or ambiguous terms in this context. Common Pitfalls: Confusing nominal vs. modular sizes after mortar joints; the terminology remains the same. Misidentifying faces when bricks are cut (closers/queen closers). Final Answer: Stretcher.

Question 15

Cavity walls — primary functions in building construction A cavity wall consists of two leaves separated by an air gap or insulated cavity and connected by ties. For what purposes are cavity walls generally provided?

Accepted Answer

Introduction / Context: Cavity walls are a widely used envelope strategy in temperate and humid climates. By separating the external and internal leaves with an air space (and sometimes adding insulation), cavity walls improve building performance and durability compared to single-leaf solid walls. Given Data / Assumptions: Two masonry leaves with a cavity and stainless/galvanized ties. Provision for damp-proofing, weep holes, and ventilation of the cavity if required. Focus on typical benefits, not specialized variants. Concept / Approach: The cavity interrupts conductive and moisture paths and can host insulation batts/boards. Thermal resistance increases, surface temperatures are stabilized, and interstitial condensation risks can be managed. The air gap and decoupled leaves also attenuate airborne noise, and the cavity acts as a barrier to rain penetration with drainage to the exterior via weep holes. Step-by-Step Solution: Thermal: air gap + insulation breaks thermal bridges → improved U-value.Acoustic: double-leaf mass-air-mass system → better sound reduction index.Damp: cavity with DPCs and weep holes prevents moisture tracking to inner leaf.Therefore all listed functions are valid. Verification / Alternative check: Building codes and façade design guides endorse cavity walls for driving rain exposure zones and for meeting energy codes with cavity insulation systems. Why Other Options Are Wrong: Each of (a)–(c) is correct; hence the combined answer is “All of the above”. Common Pitfalls: Bridging the cavity with mortar droppings or continuous ties that create thermal/damp bridges. Omitting weep holes or cavity trays over openings, causing moisture problems. Final Answer: All of the above.

Question 16

Wall footing detail — recommended depth (thickness) of lean concrete bed (PCC) For a wall footing with a lean concrete leveling bed at the bottom, what is the usual rule-of-thumb for the depth (thickness) of the PCC bed relative to its horizontal pr…

Accepted Answer

Introduction / Context: Lean concrete (plain cement concrete, PCC) is commonly provided beneath masonry wall footings as a leveling course, to distribute loads uniformly, and to create a clean working surface. Designers and estimators often use simple proportioning rules for the PCC bed to ensure adequate stiffness without waste. Given Data / Assumptions: Masonry wall footing with PCC leveling course underneath. Projection beyond wall base refers to overhang of PCC on either side. Rule-of-thumb practice as used in basic building construction. Concept / Approach: A practical proportion is to set the PCC depth approximately equal to its horizontal projection beyond the wall base. This produces a roughly triangular load spread through the PCC, aiding uniform bearing and minimizing edge breakage. Fixed minimal values (10–15 cm) may apply on small projections, but the proportional rule covers a wider range of cases more robustly. Step-by-Step Solution: Define projection p: horizontal distance from wall base edge to PCC edge.Select PCC thickness t such that t ≈ p.Check that t also meets minimum constructability (often ≥ 75–100 mm) and site compaction quality.Therefore, the best general statement is “Equal to its projection beyond the wall base”. Verification / Alternative check: Elementary texts and schedules of rates often note t = p for simple wall footings; structural designs may refine these values using bearing checks and settlement criteria. Why Other Options Are Wrong: Fixed 10 cm or 15 cm does not scale with projection and may be inadequate or wasteful. “Less than projection” provides less stiffness and edge protection than customary practice. Common Pitfalls: Neglecting proper compaction of subgrade leading to differential settlement. Omitting DPC where required, allowing rising damp into masonry. Final Answer: Equal to its projection beyond the wall base.

Question 17

Openings — what do we call the exposed vertical surfaces at right angles to a door/window frame? In door and window detailing, the portions of the wall surface that lie perpendicular (at right angles) to the frame and become exposed when an opening …

Accepted Answer

Introduction / Context: Clear terminology helps in specifying finishes, trims, and measurements around openings. Different faces around a door or window have specific names that inform plastering, painting, or cladding instructions as well as hardware placement and airtightness details. Given Data / Assumptions: Wall opening with a door or window frame fitted. Surfaces considered are the exposed wall returns at 90 degrees to the plane of the frame. Conventional building terminology is used. Concept / Approach: The vertical members of the frame itself are called jambs, while the structural horizontal over the opening is a lintel. The horizontal underside of an element is a soffit (e.g., soffit of a lintel). The exposed return surfaces of the wall that are perpendicular to the frame are called reveals. Reveals often receive plaster beads, damp-proofing details, or window tapes to ensure a neat and sealed edge. Step-by-Step Solution: Identify the element in question: not the frame, but the wall returns.Terminology: “reveal” refers to the exposed return; “jambs” are frame members.Eliminate lintel (horizontal structural member) and soffit (underside surface).Choose “Reveals” as the correct term. Verification / Alternative check: Trade specifications for plastering and window installation list “reveal plaster”, “reveal beads”, confirming standard usage of the term. Why Other Options Are Wrong: (a) Jambs are part of the frame, not the wall returns. (b) Lintel is a horizontal support, unrelated to vertical returns. (d) Soffit is the underside of an element, not the vertical return surface. Common Pitfalls: Calling the frame jamb surface a “reveal”; keep frame vs. wall distinct. Ignoring airtightness detailing at reveals leading to drafts and moisture issues. Final Answer: Reveals.

Question 18

Roof openings — name the opening in a sloping roof whose top is parallel to the roof surface In roof design, what is the term for an opening or glazed element provided in a sloping roof such that its top (upper edge) runs parallel to the roof surfac…

Accepted Answer

Introduction / Context: Daylighting devices in roofs include dormers, skylights, and lanterns, each with distinct geometries and applications. Correct naming is important for detailing, waterproofing design, and scheduling in the bill of quantities. Given Data / Assumptions: Sloping roof construction. The top of the opening is parallel to the roof surface (i.e., aligned with the slope). We are distinguishing among common roof opening types. Concept / Approach: A skylight is an opening window or glazing set in the plane of the roof slope (or curb-mounted but parallel to the surface). A dormer projects from the roof with a vertical window and its own small roof; its top edge is typically horizontal, not parallel to the main roof surface. A roof lantern is a glazed structure over a flat roof, usually raised on a curb with multiple facets. Louvered windows describe a sash style, not a roof-opening type by geometry. Step-by-Step Solution: Match geometry: opening aligned with roof slope → skylight.Exclude dormer: vertical face projection.Exclude lantern: pyramidal/hipped form on flat roofs.Exclude louvered: refers to slatted sash, not roof geometry. Verification / Alternative check: Roofing manuals detail curb and flashing kits specifically labeled for skylights installed parallel to roof slope, validating the terminology. Why Other Options Are Wrong: Dormer window is not parallel to the main roof surface. Lantern is for flat roofs and is elevated above the roof plane. Louvered describes operable slats, not the roof opening type. Common Pitfalls: Confusing skylights with sun tunnels or roof windows with different opening mechanisms. Poor flashing around skylights leading to leaks. Final Answer: Skylight window.

Question 19

Foundation systems — identify the type: thick RCC slab covering entire building area to carry heavy concentrated loads What is the correct name for a foundation that consists of a thick reinforced cement concrete slab (mat) covering the whole plan a…

Accepted Answer

Introduction / Context: When column loads are high and soil bearing capacity is low or variable, isolated footings may overlap or become excessively large. In such cases, engineers adopt a single large slab foundation that supports multiple columns and walls, distributing loads more uniformly to the soil: the raft (or mat) foundation. Given Data / Assumptions: Heavy, concentrated loads from multiple columns/walls. Single thick RCC slab covering nearly the entire building footprint. Intent is to reduce differential settlement and stress concentrations. Concept / Approach: A raft foundation behaves like a plate on an elastic foundation, spreading loads over a wide area and lowering contact pressure. It may include beams, ribs, or cellular voids depending on stiffness requirements. This contrasts with combined footings (serving two or more adjacent columns) and strap footings (connected by a beam to balance eccentricity), which do not cover the full area. Step-by-Step Solution: Identify extent: slab covers whole area → mat/raft.Check purpose: distribute heavy concentrated loads and control settlement.Exclude combined and strap alternatives which are partial-area solutions.Select “Raft footing (mat foundation)”. Verification / Alternative check: Soil-structure interaction models and design guides (e.g., plate-on-Winkler) specifically address raft/mat foundations for such loading and soil conditions. Why Other Options Are Wrong: Combined footing supports a few columns only. Strap footing connects eccentrically loaded footings, not entire area coverage. “None” is incorrect because the described system is standard as a raft/mat. Common Pitfalls: Ignoring punching shear checks under columns within the mat. Neglecting settlement analysis and groundwater uplift in deep basements. Final Answer: Raft footing (mat foundation).

Question 20

Subsurface exploration — limitations of rotary drilling Which of the following statements correctly describe limitations or drawbacks of rotary drilling for geotechnical site investigation?

Accepted Answer

Introduction / Context: Rotary drilling is a mainstay of subsurface exploration, enabling rapid penetration and continuous sampling with appropriate coring systems. However, like any method, it has limitations related to formation type, borehole conditions, and test compatibility. Recognizing these constraints leads to better investigation planning and data quality. Given Data / Assumptions: Standard rotary methods using drilling fluid or air for cuttings removal. Focus on geotechnical site investigation for foundations, not deep oil/gas wells. Small to moderate hole diameters are typical. Concept / Approach: In very coarse gravel or boulder beds, rotary methods can be inefficient or impractical because tools skate on large particles and suffer damage; percussion methods or casing advance may be preferable. Drilling fluids can mask natural groundwater levels and disturb hydraulic conductivity around the hole, complicating observation wells and falling/rising head tests. For very small boreholes, mobilisation and tooling costs make rotary drilling uneconomical compared to hand augers or lightweight systems. Step-by-Step Solution: Assess formation: very coarse gravel/boulders → poor rotary performance → (a) true.Assess hydrogeology: fluid use/disturbance → hinders GW observation/permeability → (b) true.Assess economics: sub-10 cm holes → high unit cost → (c) true.Therefore “All of the above” correctly summarizes limitations. Verification / Alternative check: Geotechnical investigation manuals recommend alternate methods (e.g., shell-and-auger, down-the-hole hammer, sonic) in coarse formations and prescribe standing periods before groundwater readings after drilling with fluid. Why Other Options Are Wrong: Any single option alone is incomplete; the method has multiple limitations as listed. Common Pitfalls: Reading groundwater immediately after drilling with bentonite slurry, leading to erroneous levels. Attempting standard permeability tests without allowing bore stabilization. Final Answer: All of the above.

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