Q: Jack arch floors (masonry arches between joists): for proper action and economy, the rise of a jack arch is commonly kept as which fraction of the clear span?

Introduction / Context: Jack arch floors consist of shallow brick or concrete arches springing between steel joists (or RCC ribs). The arch rise influences thrust, material usage, and headroom. Traditional practice adopts shallow rises for economy while maintaining adequate arch action. Given Data / Assumptions: Short-span jack arches between joists with lime/cement mortar. Shallow arch action is intended (not full semicircular arches). Rise-to-span ratio is chosen for balance between thrust and headroom. Concept / Approach: A commonly recommended rise for jack arches is about 1/12 of the span. This provides sufficient arching to reduce bending in the units and control horizontal thrusts in the joists while keeping construction depth reasonable. Step-by-Step Solution: Recall typical ratios: 1/8 to 1/12 are used, with 1/12 being a standard exam value.Select the conventional figure: 1/12 of span.Therefore, answer is 1/12 of the span. Verification / Alternative check: Old building practice manuals cite 1/12 as a good compromise for jack arches under modest spans and loads. Why Other Options Are Wrong: 1/6 or 1/8: larger rises increase thrust and reduce headroom. 1/10 or 1/15: may be used in specific cases, but 1/12 is the typical standard value taught and widely accepted. Common Pitfalls: Choosing too small a rise leading to near-flat action and higher bending; ignoring the need for adequate haunch filling and good abutment through joists. Final Answer: 1/12 of the span

Q: Roof terminology in building construction: the line formed by the intersection of two sloping roof surfaces that meet to create an external angle greater than 180° is called what?

Introduction / Context: Understanding roof terminology is essential in civil engineering and architecture for detailing, estimating, and site supervision. Roof surfaces intersect along characteristic lines with specific names that also hint at how rainwater will flow and how tiles or sheets are lapped. Given Data / Assumptions: Two sloping roof planes meet and form an external angle exceeding 180°. Common roof intersection terms include ridge, hip, and valley. We are identifying the correct line of intersection by geometry and function. Concept / Approach: A hip is a convex, outward corner line where two roof slopes meet, creating an external (obtuse) angle greater than 180°. A valley is a concave, inward (re-entrant) junction forming an internal angle that channels water. A ridge is the horizontal apex where opposite roof slopes meet at the top. Step-by-Step Solution: Identify the geometry: 'external angle > 180°' denotes a convex roof edge.Map terms to geometry: convex intersection → hip; concave intersection → valley; top horizontal → ridge.Therefore, the correct term for the line described is 'hip'. Verification / Alternative check: Roof framing drawings show hips at outer corners of L- and T-shaped plans, carrying hip rafters; valleys occur at inner corners, carrying valley rafters or valley boards. Why Other Options Are Wrong: Ridge: a horizontal apex line, not a convex corner. Valley: an internal, re-entrant angle that collects runoff. None of these: incorrect because 'hip' fits precisely. Common Pitfalls: Confusing hip and valley because both are diagonal lines on plan; their cross-sectional geometry differs (convex versus concave). Final Answer: hip

Question 1

Raft (mat) foundation bridging soft spots: for safe bridging of loose pockets in the soil mass, the soft area should be smaller than which fraction of the column spacing?

Accepted Answer

Introduction / Context: Raft (mat) foundations spread loads over a large area and can bridge over localized soft pockets. However, there are empirical limits on the permissible size of such weak zones relative to the structural grid to avoid excessive differential settlement and punching. Given Data / Assumptions: Columns rest on a continuous raft slab. A localized soft patch exists within the plan. Bridging is considered without special ground improvement. Concept / Approach: Design heuristics state that if a soft area is sufficiently small compared to the column spacing, the raft's stiffness can redistribute stresses around it, “bridging” the gap. A commonly referenced guideline is that the soft pocket should be smaller than about one-third of the column spacing for safe bridging without undue settlements. Step-by-Step Solution: Identify the governing rule-of-thumb: soft area size < (1/3) × spacing.Evaluate options: one-third meets the conventional guideline.Select “One-third the column spacing.” Verification / Alternative check: Structural-geotechnical texts suggest similar limits; beyond this, ground improvement or raft thickening/ribs may be necessary. Why Other Options Are Wrong: Half or three-fourths spacing: too large; risk of differential settlement. Full spacing/none: unconservative or undefined. Common Pitfalls: Assuming any size can be bridged by simply thickening the raft; ignoring settlements and shear checks around soft inclusions. Final Answer: One-third the column spacing

Question 2

Jack arch floors (masonry arches between joists): for proper action and economy, the rise of a jack arch is commonly kept as which fraction of the clear span?

Accepted Answer

Introduction / Context: Jack arch floors consist of shallow brick or concrete arches springing between steel joists (or RCC ribs). The arch rise influences thrust, material usage, and headroom. Traditional practice adopts shallow rises for economy while maintaining adequate arch action. Given Data / Assumptions: Short-span jack arches between joists with lime/cement mortar. Shallow arch action is intended (not full semicircular arches). Rise-to-span ratio is chosen for balance between thrust and headroom. Concept / Approach: A commonly recommended rise for jack arches is about 1/12 of the span. This provides sufficient arching to reduce bending in the units and control horizontal thrusts in the joists while keeping construction depth reasonable. Step-by-Step Solution: Recall typical ratios: 1/8 to 1/12 are used, with 1/12 being a standard exam value.Select the conventional figure: 1/12 of span.Therefore, answer is 1/12 of the span. Verification / Alternative check: Old building practice manuals cite 1/12 as a good compromise for jack arches under modest spans and loads. Why Other Options Are Wrong: 1/6 or 1/8: larger rises increase thrust and reduce headroom. 1/10 or 1/15: may be used in specific cases, but 1/12 is the typical standard value taught and widely accepted. Common Pitfalls: Choosing too small a rise leading to near-flat action and higher bending; ignoring the need for adequate haunch filling and good abutment through joists. Final Answer: 1/12 of the span

Question 3

Roof terminology in building construction: the line formed by the intersection of two sloping roof surfaces that meet to create an external angle greater than 180° is called what?

Accepted Answer

Introduction / Context: Understanding roof terminology is essential in civil engineering and architecture for detailing, estimating, and site supervision. Roof surfaces intersect along characteristic lines with specific names that also hint at how rainwater will flow and how tiles or sheets are lapped. Given Data / Assumptions: Two sloping roof planes meet and form an external angle exceeding 180°. Common roof intersection terms include ridge, hip, and valley. We are identifying the correct line of intersection by geometry and function. Concept / Approach: A hip is a convex, outward corner line where two roof slopes meet, creating an external (obtuse) angle greater than 180°. A valley is a concave, inward (re-entrant) junction forming an internal angle that channels water. A ridge is the horizontal apex where opposite roof slopes meet at the top. Step-by-Step Solution: Identify the geometry: 'external angle > 180°' denotes a convex roof edge.Map terms to geometry: convex intersection → hip; concave intersection → valley; top horizontal → ridge.Therefore, the correct term for the line described is 'hip'. Verification / Alternative check: Roof framing drawings show hips at outer corners of L- and T-shaped plans, carrying hip rafters; valleys occur at inner corners, carrying valley rafters or valley boards. Why Other Options Are Wrong: Ridge: a horizontal apex line, not a convex corner. Valley: an internal, re-entrant angle that collects runoff. None of these: incorrect because 'hip' fits precisely. Common Pitfalls: Confusing hip and valley because both are diagonal lines on plan; their cross-sectional geometry differs (convex versus concave). Final Answer: hip

Question 4

Soil mechanics: black cotton soil is generally unsuitable for shallow foundations primarily because of which property?

Accepted Answer

Introduction / Context: Foundation performance depends on soil behavior. Black cotton soils (expansive clays) are notorious for distressing lightly loaded structures due to swell–shrink cycles driven by moisture changes. Given Data / Assumptions: Soil type: expansive clay (black cotton soil). Shallow foundations without special ground improvement. Focus on the most critical adverse property. Concept / Approach: Expansive clays contain montmorillonite minerals that absorb water, increasing volume (swell), and lose water, decreasing volume (shrink). This cyclical volumetric change causes differential heave/settlement, cracking walls and floors, and rotating foundation elements—more severe than issues from mere low bearing capacity. Step-by-Step Solution: Identify hallmark of black cotton soil: high swell potential and shrinkage upon drying.Relate to foundations: volumetric changes produce seasonal heave and settlement, undermining serviceability.Select the option highlighting volumetric change due to moisture variations. Verification / Alternative check: Design remedies (under-reamed piles, moisture barriers, soil replacement/stabilization) specifically target swell–shrink, confirming that volumetric instability is the dominant concern. Why Other Options Are Wrong: Low bearing capacity: may occur but is not universal and is secondary to swell–shrink risks. Uncertain permeability: not the core issue for foundation unsuitability. Cohesion: clays are cohesive, but cohesion itself does not cause the damage mechanism; volume change does. Common Pitfalls: Designing shallow strip footings without accounting for expansive behavior, leading to cracking and tilting. Final Answer: property to undergo a volumetric change due to variation of moisture content

Question 5

Raymond pile characteristics in foundation engineering: which of the following statements about typical dimensions and shell thickness are correct?

Accepted Answer

Introduction / Context: Raymond piles are a type of cast-in-situ concrete pile formed inside a corrugated thin steel shell that is expanded or shaped. Recognizing their common dimensional ranges helps with selection and estimation. Given Data / Assumptions: Typical length range, head (top) and toe (bottom) diameters, and shell thickness trends are provided. We assess whether these are consistent with standard practice. Concept / Approach: In Raymond piles, the steel shell is often tapered; the top is wider to receive the pile cap, and the bottom smaller at the toe. The shell thickness correlates with pile size and driving conditions to prevent buckling and maintain shape during concreting. Step-by-Step Solution: Length 6–12 m: within common practice for medium-depth foundations.Top diameter 40–60 cm and bottom 20–28 cm: matches a tapered shell profile.Shell thickness depending on diameter: larger diameters and driving stresses require thicker shells.Thus, all listed statements align with typical Raymond pile specifications. Verification / Alternative check: Foundation handbooks document taper and dimensional ranges for Raymond and similar shell piles, validating the given figures. Why Other Options Are Wrong: Choosing any single statement would omit other equally correct traits; all are valid together. Common Pitfalls: Confusing Raymond piles with straight, uniform-diameter cast-in-situ piles that use removable liners. Final Answer: all the above

Question 6

Roof framing components: the horizontal member provided to support common rafters in a sloping roof is known as which element?

Accepted Answer

Introduction / Context: In timber or steel roof construction, rafters require intermediate horizontal supports to reduce span and provide fixing for roofing sheets or tiles. Correctly naming these members is important for drawings and BOQs. Given Data / Assumptions: Member is horizontal and supports common rafters. Sloping roof system with rafters, purlins, battens/laths, cleats, and struts. Concept / Approach: A purlin is a horizontal beam spanning between trusses or walls, supporting the rafters. Battens (or laths) are smaller members fixed on rafters to carry tiles/slates. Cleats are small blocks/angles used for connections or to prevent slipping. Struts are compression members providing bracing, not primary horizontal supports for rafters. Step-by-Step Solution: Match function 'supports rafters' → purlin.Exclude battens (they sit on rafters), cleats (minor connectors), and struts (bracing). Verification / Alternative check: Standard roof framing diagrams label purlins directly beneath rafters, with battens above rafters carrying the roof covering. Why Other Options Are Wrong: Batten: lighter, placed on rafters to fix tiles, not to support rafters. Cleat: a connector/support block, not a spanning member. Strut: compression brace, not a horizontal support to rafters. Common Pitfalls: Confusing purlins and battens because both are horizontal; their size and position differ. Final Answer: purlin

Question 7

Geotechnical investigation practice: select the correct statements regarding the use and spacing of inclined (oblique) boreholes during site exploration.

Accepted Answer

Introduction / Context: Site investigations often require flexibility in boring alignments to reach target strata or to sample beneath obstacles. Inclined (oblique) borings are a practical tool in an engineer’s toolkit. Given Data / Assumptions: Existing structures or services may obstruct vertical access. Geometric arrangements can combine vertical and inclined holes for coverage. Objective: correct conceptual uses of inclined borings. Concept / Approach: Inclined borings allow sampling under foundations, abutments, or pavements without disturbing them. They can supplement or, in constrained sites, replace some vertical borings. Thoughtful spacing—such as aligning one hole’s bottom under another’s collar—provides three-dimensional coverage of subsurface variability. Step-by-Step Solution: Confirm use beneath existing works → (a) is true.Recognize occasional substitution for vertical holes → (b) is true.Acknowledge spacing strategies for proper overlap and profiling → (c) is true.Therefore, 'all the above' is correct. Verification / Alternative check: Transportation and bridge projects frequently leverage inclined borings to sample beneath piers or retaining walls where vertical access is limited. Why Other Options Are Wrong: Each individual statement is correct; choosing only one would be incomplete. Common Pitfalls: Assuming vertical borings are the only acceptable approach; oblique borings are widely used when justified. Final Answer: all the above

Question 8

Masonry arches terminology: the under surface (concave face) of an arch is specifically referred to as which of the following?

Accepted Answer

Introduction / Context: Precise vocabulary in arch construction avoids confusion during setting-out and inspection. Several terms describe different parts of an arch ring and its geometry. Given Data / Assumptions: We identify the name of the under surface of an arch. Common related terms appear as options. Concept / Approach: The intrados is the inner, concave curve that forms the arch’s visible under surface. The term soffit is a general word for the underside of architectural members; in arches, soffit is often used synonymously with intrados, but 'intrados' is the specific technical term for the arch profile. The haunch is the part between crown and springing, and the back is the extrados or upper outer curve. Step-by-Step Solution: Match 'under surface of arch' → the inner curve = intrados.Recognize 'soffit' as a general underside term, but the arch-specific term sought is intrados. Verification / Alternative check: Standard texts define intrados as the inner curve; extrados (back) as the outer curve. Why Other Options Are Wrong: Soffit: generic underside; less precise than intrados here. Haunch: zone of the arch, not the underside curve itself. Back: the outer (extrados) surface, not the inner. Common Pitfalls: Using 'soffit' generically; exam questions typically prefer 'intrados' for specificity. Final Answer: intrados

Question 9

Staircase proportioning rule: in stair design, the commonly used comfort relationship between the rise (R) and the going/tread (G) is kept approximately equal to which value?

Accepted Answer

Introduction / Context: Designing comfortable and safe stairs involves proportioning the rise and going so that users can walk naturally. Rules of thumb relate R and G to a target value based on human gait. Given Data / Assumptions: Rise R and going G are measured in millimetres. Use of standard ergonomic proportions. Question expects the widely taught comfort rule. Concept / Approach: The classic Blondel formula is 2R + G ≈ 600 mm (often within 600–650 mm). This places steps within a comfortable stride range. Other variants like R + G ≈ 450 mm appear, but 2R + G is the most recognized basis for proportioning. Step-by-Step Solution: Identify the intended ergonomic relationship → Blondel's rule.Select the benchmark value commonly rounded to 600 mm.Therefore, the answer is 600. Verification / Alternative check: Building codes and handbooks endorse ranges like R between 150–190 mm and G between 250–300 mm, which satisfy 2R + G around 600–640 mm. Why Other Options Are Wrong: 350/420/450/500 do not represent the standard 2R + G comfort target for most occupancies. Common Pitfalls: Confusing the rule as a product R*G; the common comfort relation uses a sum with 2R. Final Answer: 600

Question 10

Concrete workability guideline: what slump range (in mm) is typically recommended for placing reinforced concrete in beams and slabs?

Accepted Answer

Introduction / Context: Slump is a quick measure of concrete workability. For beams and slabs, adequate workability eases placement and compaction without segregation, ensuring cover and finish quality. Given Data / Assumptions: Normal reinforced concrete using conventional vibration. Ambient conditions are typical; no special admixtures like SCC assumed. Recommended slump ranges are those widely used in site practice and teaching references. Concept / Approach: Beams and slabs generally require medium workability. A slump of about 25–75 mm is commonly recommended for reinforced sections placed with needle vibrators. Higher slumps may be used with plasticizers but risk segregation if not controlled; very low slumps hamper compaction around reinforcement. Step-by-Step Solution: Identify member type: beams and slabs → medium workability.Select standard range → 25 to 75 mm. Verification / Alternative check: Site method statements and handbooks list 25–75 mm for RCC beams/slabs, 75–100 mm for columns/walls where flow around congested bars is needed. Why Other Options Are Wrong: 25–50 mm: on the leaner side; may be acceptable but lower bound of common practice. 50–100 mm or 30–125 mm: higher workability ranges more typical for heavily reinforced members or with admixtures; not the standard teaching answer. None of these: incorrect because 25–75 mm is appropriate. Common Pitfalls: Using high slump without admixtures, leading to segregation and bleeding. Final Answer: 25 to 75 mm

Question 11

Door hardware terminology: a small wooden block hinged on the post outside a door, used to hold or secure the shutter, is commonly known as what?

Accepted Answer

Introduction / Context: Site carpentry uses specific terms for simple door accessories. Correct naming improves BOQ descriptions and communication with artisans. Given Data / Assumptions: A small wooden block is hinged on the post outside a door to retain or secure the shutter. We distinguish between stops, cleats, and horns. Concept / Approach: A door stop (or rebate) is usually a fixed strip on the frame, not hinged. Horns are projecting ends of door/window frames embedded into masonry, not accessories. A cleat in carpentry is a small block or strip that can be fixed or hinged to catch/retain a shutter—fitting the description given (a simple hinged block outside acting as a hold-back). Step-by-Step Solution: Identify the key feature: hinged small block on the post outside.Match with terminology: this aligns with a hinged cleat used to hold the door.Therefore, select 'cleat'. Verification / Alternative check: Traditional joinery details show hinged wooden cleats/turn buttons used to retain shutters; stops are fixed. Why Other Options Are Wrong: Stop: fixed rebate/strip; not hinged and typically on the closing face inside. Horn: frame projection for embedment in masonry. None of these: incorrect because 'cleat' matches. Common Pitfalls: Calling any retaining piece a stop; here the hinging feature distinguishes a cleat. Final Answer: cleat

Question 12

Damp-proof course (horizontal D.P.C.) in masonry: what is the typical thickness of cement concrete (1:2:4) provided as a horizontal D.P.C. layer?

Accepted Answer

Introduction / Context: A horizontal damp-proof course (D.P.C.) prevents capillary rise of moisture from foundations into walls and floors. Correct thickness and mix ensure durability and continuity under walls. Given Data / Assumptions: D.P.C. material: cement concrete of proportion 1:2:4 (cement:sand:coarse aggregate) with waterproofing admixture where specified. We seek typical thickness adopted in practice. Concept / Approach: For load-bearing walls, a 4 cm thick cement concrete D.P.C. is commonly provided at plinth level, finished smooth to receive the first course of masonry. Thicker layers may be used for special cases or alternative materials (e.g., mastic asphalt), but the standard teaching value remains 4 cm. Step-by-Step Solution: Identify standard practice: 1:2:4 CC D.P.C. at plinth.Select typical thickness from options: 4 cm. Verification / Alternative check: Building specifications and measurement handbooks frequently state 'CC 1:2:4, 40 mm thick, with waterproofing compound' for horizontal D.P.C. under walls. Why Other Options Are Wrong: 2 cm: too thin and prone to cracking/voids. 6–10 cm: unnecessarily thick for a D.P.C. layer; increases cost without added benefit. Common Pitfalls: Omitting continuity across wall thickness or not lapping D.P.C. with floor membranes, leading to moisture bridges. Final Answer: 4 cm

Question 13

In building construction terminology, the exterior angle formed between the outer faces of two meeting walls is called what?

Accepted Answer

Introduction / Context: The geometry of wall intersections is fundamental vocabulary in brickwork and stone masonry. Accurately naming the outer corner where two wall faces meet helps in detailing, measurement, estimating, and specification for corner treatments, protections, and aesthetics. Given Data / Assumptions: Two masonry wall faces meet externally forming an outer corner. We are asked for the specific term used in civil/architectural practice. Standard masonry terminology applies. Concept / Approach: The exterior angle between the outer faces of a wall is termed the quoin. In practice, quoins may be emphasized using special stones or bricks (quoin stones/quoins) for strength and visual accent. The word “junction” is a general meeting of parts and “turn” is not a standard technical name here. “Arris” refers to the sharp edge formed by two surfaces meeting, not the corner assembly itself. Step-by-Step Solution: Identify the feature: an external corner of masonry.Match to terminology: external corner → quoin.Exclude generic terms (junction/turn) and misapplied terms (arris).Therefore, the correct term is quoin. Verification / Alternative check: Standard building construction texts classify corners as quoins (external) and re-entrant angles (internal). Quoin stones are commonly detailed in ashlar or dressed masonry. Why Other Options Are Wrong: Junction: too general; does not specify an external masonry corner. Turn: not a standard term for this feature. All of the above: incorrect since only one precise term fits. Arris: the sharp edge line, not the corner assembly. Common Pitfalls: Confusing “arris” (edge) with “quoin” (corner). Assuming any meeting is a “junction” without recognizing specific masonry terminology. Final Answer: Quoin (exterior corner)

Question 14

Brick identification on elevation: the 9 cm × 9 cm square face of a standard brick seen on the wall face is termed what in brick masonry?

Accepted Answer

Introduction / Context: In brick masonry, names depend on which dimension of the brick is exposed on the wall face. Correctly identifying header and stretcher appearances is essential for interpreting bond patterns (English, Flemish) and for estimating and specifying work. Given Data / Assumptions: Standard Indian modular brick nominal size ~ 19 × 9 × 9 cm (or conventional 9 × 4.5 × 3 in.). On the wall face, the exposed square face measures approximately 9 cm × 9 cm. Conventional brick terminology is used. Concept / Approach: When the shorter dimension (breadth) is presented on the face with the brick laid through the thickness, the visible square is the header face (about 9 × 9 cm). A stretcher shows the long rectangular face (about 19 × 9 cm). Terms like “front,” “side,” or “face” are non-technical descriptors and do not replace the masonry terms. Step-by-Step Solution: Identify the seen face: 9 cm × 9 cm square on elevation.Relate to brick orientation: short side shown → header.Therefore, the correct term is “Header.” Verification / Alternative check: Bond diagrams show alternating headers and stretchers; headers appear as 9 × 9 squares; stretchers as 19 × 9 rectangles. Why Other Options Are Wrong: Stretcher: exposes the long face (≈ 19 × 9 cm), not square. Front/Side/Face: generic words; lack technical specificity. Common Pitfalls: Mixing up header and stretcher appearances; forgetting nominal size conventions. Final Answer: Header

Question 15

Selection of building stone: which rock is traditionally preferred for monumental buildings due to its appearance and workability?

Accepted Answer

Introduction / Context: Monumental architecture emphasizes durability, finish, and visual impact. Stone selection depends on strength, polish, carvability, and weathering. This question asks which rock is classically associated with monuments. Given Data / Assumptions: We compare common building stones: marble, granite, sandstone, slate. Criteria: aesthetics (color/veining), ability to take polish, carvability, and cultural precedent. Concept / Approach: Marble, a metamorphosed limestone, is prized for fine texture, ability to take a high polish, and suitability for intricate carving—hence used in many monuments (e.g., memorials, temples). Granite is stronger and highly durable but harder to carve; it is used for structural or monumental blocks but less for fine sculptural detailing. Sandstone is workable and widely used historically; however, for high-finish monumental surfaces marble remains a classic choice. Slate is typically used for roofing and cladding, not monumental statuary. Step-by-Step Solution: Evaluate desired properties: polish + carvability + prestige.Marble best satisfies these for monumental architecture.Therefore, select “Marble.” Verification / Alternative check: Architectural history shows extensive marble use in mausoleums, statues, and interior monumental finishes due to its luster and fine grain. Why Other Options Are Wrong: Granite: excellent durability but difficult to carve; typically for plinths/columns. Sandstone: workable but usually for general masonry; polish/finish inferior to marble. Slate: foliated rock for roofing/flooring, not for monumental carvings. Common Pitfalls: Equating maximum strength with suitability for sculpture; ignoring finishing qualities required for monuments. Final Answer: Marble

Question 16

Precast concrete piles: what is the maximum recommended taper along the length to ensure sound casting, handling, and driving performance?

Accepted Answer

Introduction / Context: Precast reinforced concrete piles may be slightly tapered to facilitate driving and stress distribution. However, excessive taper can cause nonuniform stresses, driving damage, and casting difficulties. Codes and practice guides limit the taper. Given Data / Assumptions: Precast R.C.C. piles (square or octagonal) with modest taper are considered. Good practice limits taper to a small value per metre length. Objective: ensure safe handling, uniform driving, and structural adequacy. Concept / Approach: A typical recommendation is that the taper of precast concrete piles should not exceed about 1 cm per metre of length. This small taper eases penetration while keeping cross-section changes gradual enough to avoid stress concentrations and reinforcement congestion. Step-by-Step Solution: List plausible tapers: 1, 2, 4, 5 cm/m.Adopt conservative practice for precast concrete: 1 cm/m.Therefore, the correct limit is 1 cm per metre. Verification / Alternative check: Comparatively, timber piles may have larger natural tapers; precast concrete members favor minimal taper for reinforcement layout and casting formwork stability. Why Other Options Are Wrong: 2–5 cm/m: too steep for precast concrete, risking cracking and driving damage. No taper: permissible but not necessary; slight taper is common—question asks for the maximum recommended, not zero. Common Pitfalls: Applying timber pile taper limits to concrete piles; ignoring reinforcement detailing constraints in tapered sections. Final Answer: 1 cm per metre length

Question 17

Rankine's empirical design: according to Rankine's formula, what is the minimum depth D of foundation embedment in terms of soil unit weight γ, allowable bearing pressure q (at foundation level), and soil friction angle φ?

Accepted Answer

Introduction / Context: Rankine's depth of foundation formula provides a minimum embedment to prevent shear failure and ensure the overburden confining pressure mobilizes adequate passive resistance. It relates the foundation depth to soil strength parameters in a simple closed form widely used for preliminary sizing. Given Data / Assumptions: Soil unit weight = γ (kN/m^3). Allowable bearing pressure at foundation level = q (kN/m^2). Effective stress friction angle = φ (degrees). Groundwater effects and cohesion are neglected for simplicity. Concept / Approach: Rankine's active earth pressure coefficient K_a = ((1 − sin φ) / (1 + sin φ))^2. The classic embedment relation may be written as D = (q / (γ K_a)), which rearranges to D = (q / γ) * ((1 − sin φ) / (1 + sin φ))^2. This ensures that vertical overburden at the base provides the confining stress consistent with allowable pressure. Step-by-Step Solution: Compute K_a = ((1 − sin φ) / (1 + sin φ))^2.Use D = (q / (γ K_a)).Substitute K_a: D = (q / γ) * ((1 − sin φ) / (1 + sin φ))^2.Thus, option (a) matches Rankine's expression. Verification / Alternative check: For φ = 0°, K_a = 1, giving D = q / γ, which is dimensionally consistent and physically reasonable for purely frictionless soil in this simplified context. Why Other Options Are Wrong: (b) Linear (not squared) ratio; does not reflect Rankine's K_a. (c) Inverts the ratio, yielding unrealistic shallow/negative depths. (d) and (e) use tan(45° ± φ/2) forms without the square; not Rankine's embedment formula. Common Pitfalls: Confusing K_a (active) with K_p (passive); omitting the square on ((1 − sin φ)/(1 + sin φ)). Final Answer: D = (q / γ) * ((1 - sin φ) / (1 + sin φ))^2

Question 18

Placement of a queen closer in brick bonds: where should a queen closer be positioned to maintain proper bond and stagger of vertical joints?

Accepted Answer

Introduction / Context: Closers are specially cut bricks used to maintain the interlocking bond at corners (quoins). A queen closer is obtained by cutting a brick longitudinally into two equal halves (half the width along the full length). Correct placement is crucial for breaking vertical joints and achieving a durable corner. Given Data / Assumptions: We are dealing with standard bonds such as English or Flemish. Corner (quoin) bonding must avoid straight-through vertical joints. Queen closer definition: longitudinal half-brick. Concept / Approach: In English bond, the queen closer is typically placed in the header course next to the first quoin header to ensure that the vertical joints of the two faces do not align. This placement maintains the required overlap between adjacent courses, improving strength and appearance. Step-by-Step Solution: Identify the course type: header course at the corner.Place queen closer adjacent to the first header at the quoin.This creates correct joint staggering between faces. Verification / Alternative check: Textbook bond diagrams consistently show queen closers against the first header in header courses to maintain bond around corners. Why Other Options Are Wrong: Stretcher-course placements do not achieve the required quoin interlock in English bond. “Any position” or “random” placement can produce continuous joints. Keeping it in header courses but not next to the first brick fails to correct the joint alignment at the corner. Common Pitfalls: Confusing queen closer with king closer; placing closers in the wrong course, leading to weak corners. Final Answer: In a header course next to the first brick at the quoin

Question 19

Piling systems: the pile that develops an enlarged bulb at its lower end by compacting/ramming concrete to form an expanded base is called what?

Accepted Answer

Introduction / Context: Different proprietary pile systems were developed to improve load capacity by enlarging the base or improving shaft interaction. Recognizing the system by its construction method is a common exam theme in foundation engineering. Given Data / Assumptions: Pile is provided with a bulb/expanded base at its lower end. Bulb is formed by ramming/compacting concrete at the toe. Terminology references classic pile types. Concept / Approach: The Franki pile (also known as an expanded-base pile) uses a dry concrete plug driven at the toe of a casing; then concrete is rammed to form an enlarged bulb. This increases end-bearing area and mobilizes higher resistance. Other types (Simplex, Mac-Arthur, Raymond) use different erection and concreting methods and typically do not create such a compacted bulb in the same way. Step-by-Step Solution: Identify key feature: expanded bulb formed by ramming concrete at the toe.Match with system name: Franki pile.Select “Franki pile (expanded base).” Verification / Alternative check: Standard foundation references describe the Franki method with a toe plug and subsequent bulb formation to enhance capacity. Why Other Options Are Wrong: Simplex/Mac-Arthur/Raymond: methods differ (e.g., driven shells, collapsible forms) and are not characterized by a compacted expanded bulb at toe in this manner. None of these: incorrect because a named type exists. Common Pitfalls: Confusing Raymond's thin-shell process with Franki's expanded-base technique; assuming all cast-in-situ piles form bulbs. Final Answer: Franki pile (expanded base)

Question 20

Climatic design: which factors must be considered when deciding the orientation of buildings for comfort and energy performance?

Accepted Answer

Introduction / Context: Building orientation strongly influences thermal comfort, daylighting, and ventilation. Passive design integrates wind patterns, sun paths, and shading elements (like verandahs) to reduce cooling loads and improve livability without heavy reliance on mechanical systems. Given Data / Assumptions: Local climate provides dominant winds and seasonal sun angles. Building has facades, roofs, and verandahs that interact with sun and wind. Goal: optimize comfort and energy efficiency. Concept / Approach: Designers consider: (a) Prevailing winds for cross-ventilation and night purging; (b) Solar exposure of walls/roof to control heat gain using orientation and shading; (c) Solar penetration under verandahs to admit winter sun and exclude summer sun via appropriate overhang geometry (altitude/azimuth-based). Step-by-Step Solution: Account for wind direction: align openings to capture breezes while avoiding dust or driving rain.Analyze sun path: orient longer facades favorably, add shading to high-gain orientations.Size verandahs/overhangs: set projection and height to achieve desired seasonal penetration.Thus, all listed factors are essential. Verification / Alternative check: Climate-responsive design guidelines consistently emphasize wind orientation, solar exposure, and shading geometry as a trio for orientation decisions. Why Other Options Are Wrong: Selecting only some factors ignores the integrated nature of passive design. Common Pitfalls: Overlooking local microclimate; undersizing overhangs; ignoring roof heat gains. Final Answer: All of the above

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