LESSON 8.1 — Structural Principles and Load Types

A. Standard Map

Topic	Governing Source	Exam Focus
Dead / live loads	IS 875 Parts 1–2	Unit weights; occupancy LL by use
Wind / snow	IS 875 Parts 3–4	Windward pressure; roof suction < 30° slope
Seismic	IS 1893:2016	Not IS 875; equivalent static base shear
Load combinations	IS 456 Annex B	1.5 DL + 1.5 LL; wind/seismic not combined
Slenderness	IS 456 Cl. 25.1.2	λ = Le/r; short if λ ≤ 12
Load path	—	Slab → beam → column → footing → soil

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B. Why It’s Used

Structural principles and load types form the analytical foundation for all structural design decisions. GATE AR tests load classification (dead, live, wind, seismic, snow), load paths, truss analysis (zero force members, method of joints/sections), beam bending and shear force diagrams (SFD/BMD), and structural system identification for tall buildings as MCQ and NAT questions. This is the highest NAT-density lesson in Ch8.

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C. Mechanism in Words

1. Classify each load by source, nature (static/dynamic), and governing code.
2. Select the critical load combination for the design situation (gravity, uplift, lateral).
3. Map the load path through members — stiffness attracts load; infill is not structural.
4. Identify the dominant structural action (compression, bending, shear) at each member.
5. Check slenderness and stability where compression or lateral drift governs.

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D. Core Concept Explanations

C1. Load Classification

Load Classification by Source

Load Type	Nature	Origin	Indian Code	Critical for
Dead Load (DL)	Static	Self-weight of structure + permanent non-structural elements (walls, finishes, fixed equipment)	IS 875 Part 1	All design situations
Live / Imposed Load (LL)	Static / quasi-static	Occupancy: people, furniture, stored goods; variable in magnitude and position	IS 875 Part 2	Floors, beams, columns
Wind Load (WL)	Dynamic (treated statically)	Air pressure and suction on building surfaces	IS 875 Part 3	Tall/slender/lightweight structures
Snow Load (SL)	Static	Accumulated snow on roofs; geography-dependent	IS 875 Part 4	Hill-station buildings (Shimla, Gulmarg, Gangtok)
Seismic Load (EL)	Dynamic	Ground acceleration → inertial forces in the building mass	IS 1893:2016	All buildings; zones II–V
Impact Load	Dynamic	Sudden application → dynamic amplification of LL	IS 875 Part 2 (Annex)	Elevator machinery, cranes, vehicle impact
Earth Pressure	Static	Lateral soil pressure on basement walls and retaining structures	IS 1893 / IS 3370	Basement/substructure
Hydrostatic Pressure	Static	Upward force from high water table on foundation slabs	IS 3370	Foundation slab
Settlement Load	Static	Differential settlement → induced stresses	—	Foundation design

Static vs Dynamic — Structural Distinction

Criterion	Static Load	Dynamic Load
Application rate	Gradual; inertia negligible	Rapid; inertia forces significant
Structural response	Quasi-static equilibrium	Time-dependent; resonance risk
Design approach	Equivalent static force	Response spectrum / time-history (IS 1893)
Examples	DL, LL, SL, earth pressure	Seismic, impact, blast, wind gust (flutter)

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C2. IS 875 — Parts 1–5 Scope

IS 875 Reference Table

Part	Title	Load Governed	Key Output
Part 1 (1987)	Dead Loads — Unit Weights of Building Materials and Stored Materials	Permanent gravity loads	Unit weights (kN/m³) for concrete, masonry, soil, finishes, stored goods
Part 2 (1987)	Imposed Loads	Occupancy / live loads	Floor LL by occupancy type (residential 2.0 kN/m², office 4.0 kN/m²); roof LL; impact factors
Part 3 (2015)	Wind Loads	Wind pressure and suction	Design wind speed Vz; wind pressure pz = 0.6Vz²; pressure/suction coefficients (Cp); critical for tall/lightweight structures
Part 4 (1987)	Snow Loads	Snow accumulation on roofs	Ground snow load → roof snow load; shape coefficients by roof geometry
Part 5 (1987)	Special Loads and Load Combinations	Combined load effects	Guidelines for load combinations; special loads (thermal, vibration, erection)

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C3. Load Combinations

Load Combination Logic

Load combinations ensure that the worst simultaneous loading is considered. The governing combination depends on the design situation.

Combination	Expression (LSM — IS 456)	Governs For
DL + LL	1.5 DL + 1.5 LL	Standard gravity design (beams, slabs, columns in low-rise)
DL + WL	0.9 DL + 1.5 WL	Uplift / overturning check (roof, foundation with net upward wind)
DL + LL + WL	1.2 DL + 1.2 LL + 1.2 WL	Tall buildings; lateral + gravity combined
DL + LL + EL	1.2 DL + 1.2 LL ± 1.2 EL	Seismic zone design (IS 1893)
DL + EL	0.9 DL ± 1.5 EL	Overturning under seismic; minimum gravity stabilises
DL only	1.5 DL	Dead load alone (erection stage; pre-cast before LL applied)

Which Combination Governs Which Situation

Design Situation	Critical Combination	Why
Simply supported beam in a residential building	1.5 DL + 1.5 LL	Wind/seismic irrelevant for gravity spans
Column in a 25-storey building	1.2 (DL + LL + WL)	Wind moment governs column design at upper floors
Foundation uplift check	0.9 DL + 1.5 WL	Minimum gravity vs maximum uplift — 0.9 factor reduces stabilising effect
Shear wall at base	0.9 DL ± 1.5 EL	Seismic overturning governs foundation and shear wall design
Flat roof — lightweight structure	0.9 DL + 1.5 WL	Net upward wind suction may exceed dead weight

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C4. Structural Actions — Member Behaviour

Structural Actions Table

Action	Definition	Stress Type Induced	Typical Member	Visual Sign
Compression	Member shortens under axial load along its axis	Compressive stress (σ = P/A)	Column, arch rib, top chord of truss	Shortening / lateral buckling if slender
Tension	Member elongates under axial pull	Tensile stress (σ = P/A)	Tie, bottom chord of truss, hanger	Elongation; no buckling risk
Bending	Transverse load creates curvature; top fibres in compression, bottom in tension (sagging)	Bending stress (σ = M·y/I); varies linearly across section	Beam, slab, rafter	Deflection; cracking at tension face in RC
Shear	Forces parallel to cross-section; tendency for one part to slide past another	Shear stress (τ = VQ/Ib); max at neutral axis	Beam web, column base, connection	Diagonal tension cracks (45°) in RC beams
Torsion	Twisting about the longitudinal axis; force offset from shear centre	Shear stresses around the section periphery	Spandrel beam, eccentrically loaded beam	Warping; helical cracking
Combined Bending + Axial	Column carries axial load + moment (eccentric loading)	Bending + direct stress; one face has higher compression	Eccentrically loaded column, beam-column	Unsymmetric stress distribution

Member Type vs Dominant Action

Member	Primary Action	Secondary Action
Column	Compression	Bending (if eccentric or lateral load)
Beam	Bending	Shear
Tie / bracing diagonal	Tension	—
Arch rib	Compression	Bending (if non-funicular load)
Slab	Bending (two-way or one-way)	Shear (punching at columns)
Spandrel beam	Torsion + Bending	Shear
Footing	Bending (cantilever from column)	Punching shear

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C5. Slenderness and Buckling

Slenderness Ratio

Slenderness ratio λ quantifies a compression member’s susceptibility to buckling (lateral instability under axial load):

λ = Le / r

Where:
– Le = effective length of the column (depends on end conditions; see table below)
– r = least radius of gyration of the cross-section = √(I/A); use the minimum I about any axis

End Condition	Effective Length Le	Multiplier on actual length L
Both ends pinned (free to rotate, held in position)	L	1.0 L
One end fixed, other end pinned	0.7 L	0.7 L
Both ends fixed (no rotation, no translation)	0.5 L	0.5 L
One end fixed, other end free (cantilever)	2.0 L	2.0 L

Euler Buckling — Awareness Level

Euler’s formula gives the critical load at which a theoretically perfect slender column buckles:

Pcr = π² E I / Le²

• Pcr is the theoretical elastic buckling load (N)
• E = modulus of elasticity of material (N/mm²)
• I = second moment of area (mm⁴) about the axis of buckling
• Le = effective length (mm)

Exam-level awareness:
– Buckling load decreases as Le² — doubling the effective length reduces Pcr by 75%.
– Buckling always occurs about the axis of least I (or least r).
– Real columns buckle below Pcr due to initial imperfections, eccentricity, and material nonlinearity.
– Euler applies only to slender, elastic columns — not to short RC columns.

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C6. Load Path

Gravity Load Path — Frame Building

The load path is the route by which applied loads travel from the point of application to the ground. Loads follow the path of least resistance (highest stiffness).

Roof/Floor Live + Dead Load
        ↓
    Slab (bending — transfers load to supporting beams/walls)
        ↓
    Beam (bending + shear — collects slab loads; spans to columns)
        ↓
    Column (compression ± bending — stacks loads floor-by-floor)
        ↓
    Footing / Foundation (spreads concentrated column load over soil)
        ↓
    Soil (bearing pressure; must not exceed safe bearing capacity)

Principles Governing Load Path

Principle	Implication
Stiffness attracts load	A stiffer element carries more load; shear walls attract more lateral force than adjacent columns
Continuity of path	Any break in the load path (missing column, inadequate connection) creates a local overstress
Short path is efficient	Loads travel the shortest continuous stiff path; longer paths increase member forces
Infill ≠ load-bearing	Brick infill in RC frames is NOT part of the structural load path unless designed as such; it creates stiffness irregularity, not load carrying capacity
Tributary area determines beam load	Each beam carries load from the slab area tributary to it; interior beams carry twice the area of edge beams

Load Path in Wall-Dominant (Masonry) System

Roof/Floor Load
      ↓
Roof Slab / Beams
      ↓
Load-Bearing Wall (direct compression path)
      ↓
Strip / Spread Footing
      ↓
Soil

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C7. Lateral Stability

Why Lateral Stability Requires Dedicated Systems

Gravity frames (beams + columns with simple/pin connections) resist vertical loads efficiently but provide little resistance to horizontal forces (wind, seismic). Without a lateral system:
– Columns act as vertical cantilevers — highly inefficient in bending
– The frame undergoes large sway (inter-storey drift)
– P-Δ effects amplify moments and risk collapse

Lateral Stability Systems

System	Mechanism	Height Range	Key Feature
Shear Wall	In-plane stiffness of RC wall resists lateral force as a vertical cantilever; also carries gravity	Up to ~35 storeys	Most common in Indian mid-rise; placed at cores/lift shafts
Braced Frame	Diagonal bracing members create triangulated zones; lateral force carried in axial action (not bending)	30–50 storeys	More efficient than moment frame; braces restrict openings
Moment-Resisting Frame	Rigid beam-column connections resist rotation; frame sways but develops moments at joints	Up to ~20–25 storeys	Flexible floor plans; bending-dominated = less efficient
Core + Outrigger	Stiff RC core plus deep outrigger beams engaging perimeter columns	40–60 storeys	Outriggers dramatically increase effective depth of lateral system

Why Bracing and Shear Walls Matter

• Without lateral stiffness, a tall building behaves as an unbraced cantilever of enormous height → drift governs, not strength.
• Drift limit (IS 1893): Inter-storey drift under design seismic force ≤ 0.004 × storey height.
• Shear walls provide stiffness far exceeding that of equivalent column area → preferred for seismic zones.
• Shear walls at the perimeter (symmetrically placed) minimise torsional response under seismic loading.

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E. Worked Numericals and Parameter Tables

Load Combination Reference Table + Worked Numericals

Load Combination Quick-Reference

#	Combination	LSM Factors	Common Use Case
LC1	DL + LL	1.5 DL + 1.5 LL	Beam / slab gravity design
LC2	DL + WL	0.9 DL + 1.5 WL	Uplift / overturning
LC3	DL + LL + WL	1.2 DL + 1.2 LL + 1.2 WL	Tall building — lateral + gravity
LC4	DL + LL + EL	1.2 DL + 1.2 LL ± 1.2 EL	Seismic zone design
LC5	DL + EL	0.9 DL ± 1.5 EL	Seismic overturning / foundation uplift

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Numerical (a): Simply Supported Beam — UDL

Problem:
A simply supported RC beam spans 6 m. It carries a superimposed dead load (SDL, finishes + partitions) of 4 kN/m and a live load of 8 kN/m. The beam self-weight is 6 kN/m. Determine:
(i) Total factored UDL (using LC1)
(ii) Maximum factored bending moment
(iii) Maximum factored shear force
(iv) Serviceability check — is the span/effective depth ratio adequate if effective depth d = 500 mm?

Solution:

Step 1 — Unfactored loads:
– DL = Self weight + SDL = 6 + 4 = 10 kN/m
– LL = 8 kN/m

Step 2 — Factored UDL (LC1: 1.5 DL + 1.5 LL):
– wu = 1.5 × 10 + 1.5 × 8 = 15 + 12 = 27 kN/m

Step 3 — Maximum factored bending moment:
$$M_{max} = frac{w_u L^2}{8} = frac{27 times 6^2}{8} = frac{27 times 36}{8} = frac{972}{8} = textbf{121.5 kN·m}$$
Location: at midspan

Step 4 — Maximum factored shear force:
$$V_{max} = frac{w_u L}{2} = frac{27 times 6}{2} = textbf{81 kN}$$
Location: at supports

Step 5 — Serviceability check (IS 456:2000, Cl. 23.2.1):
– Basic span/effective depth ratio for simply supported beam = 20 (for spans ≤ 10 m)
– Required d ≥ L/20 = 6000/20 = 300 mm
– Provided d = 500 mm > 300 mm ✓
– Span/depth check is satisfied. (Note: IS 456 applies modification factors for steel stress and tension reinforcement percentage; base value 20 is the starting benchmark.)

Summary:
| Quantity | Value |
|—|—|
| Factored UDL wu | 27 kN/m |
| Mmax (factored) | 121.5 kN·m at midspan |
| Vmax (factored) | 81 kN at supports |
| Span/depth check | 500 mm > 300 mm ✓ |

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Numerical (b): Column Slenderness Ratio

Problem:
An RC column has an unsupported height of 4.0 m. Both ends are fixed against rotation but free to translate (i.e., sway frame). The column section is 300 mm × 450 mm. Determine:
(i) Effective length Le
(ii) Least radius of gyration r
(iii) Slenderness ratio λ
(iv) Classify as short or slender

Solution:

Step 1 — Effective length:
For both ends fixed, no sway: Le = 0.65 L (IS 456 Table 28 / NBC Part 6)
For sway frame (fixed-fixed with sway): Le = 1.2 L
Using sway condition (more common in practice): Le = 1.2 × 4000 = 4800 mm

Step 2 — Cross-section properties:
– b = 300 mm, D = 450 mm
– I_min = (300³ × 450)/12 — wait, use the smaller dimension for minimum I:
– I_min = (b³D)/12 — about the axis along D:
– I_min = (300)³ × 450 / 12 — No. Correct approach:
– About the minor axis (parallel to 450 mm face): I_minor = D × b³/12 = 450 × 300³/12 = 450 × 27,000,000/12 = 1,012,500,000 / 12 = 1.0125 × 10⁹ mm⁴

Actually, simplifying with standard formula:
– I_minor (about axis parallel to longer dimension) = (D · b³)/12 = (450 × 300³)/12
– = (450 × 27,000,000)/12 = 12,150,000,000/12 = 1,012.5 × 10⁶ mm⁴

• A = 300 × 450 = 135,000 mm²

Step 3 — Least radius of gyration (about minor axis):
$$r_{min} = sqrt{frac{I_{min}}{A}} = sqrt{frac{1,012.5 times 10^6}{135,000}} = sqrt{7,500} = textbf{86.6 mm}$$

Quick check: for a rectangle, r = b/√12 = 300/3.464 = 86.6 mm ✓

Step 4 — Slenderness ratio:
$$lambda = frac{L_e}{r_{min}} = frac{4800}{86.6} = textbf{55.4}$$

Step 5 — Classification (IS 456 Cl. 25.1.2):
– λ = 55.4 >> 12 → Slender (long) column
– Slender columns require design for additional moment due to P-Δ effects (IS 456 Cl. 39.7).

Summary:
| Parameter | Value |
|—|—|
| Unsupported height L | 4,000 mm |
| Effective length Le (sway) | 4,800 mm |
| Section | 300 × 450 mm |
| I_minor | 1,012.5 × 10⁶ mm⁴ |
| Area A | 135,000 mm² |
| r_min | 86.6 mm |
| Slenderness ratio λ | 55.4 |
| Classification | Slender column (λ > 12) |

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F. Design Criteria

Concept	Key Parameter
Dead Load (DL)	Self-weight of permanent structure components (IS 875 Part 1)
Live Load (LL)	Occupancy loads; residential 2.0 kN/m²; office 3.0 kN/m²; corridor 4.0 kN/m² (IS 875 Part 2)
Wind Load	Depends on terrain, height, shape; basic wind speed map; IS 875 Part 3
Seismic Load	Zone factor × Sa/g × importance factor; IS 1893:2016
Zero force member (truss)	Member with no force in a given load case; identified by inspection at joints with 2 non-collinear members
Soft storey	Storey lateral stiffness < 70% of storey above; failure mode = shear failure during seismic loading
Bundled tube system	Multiple tubes in a bundle sharing lateral loads; Sears Tower (Willis Tower) Chicago
Framed tube system	Closely spaced columns + deep spandrels; World Trade Center towers

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Code Comparisons

Code	Scope	Key Value
IS 875 Part 1	Dead loads	Unit weights: RCC 25 kN/m³; brick masonry 20 kN/m³; steel 78.5 kN/m³
IS 875 Part 2	Live loads	Residential 2 kN/m²; office 3 kN/m²; public assembly 5 kN/m²
IS 875 Part 3	Wind loads	Basic wind speed; terrain categories; gust factor
IS 1893 Part 1:2016	Seismic loads	Zone factors II–V; response spectra; importance factors
IS 456:2000	RCC design	Limit state design; load combinations

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G. Application Zones

• Seismic design: Soft storey identification and stiffness distribution determines IS 13920 ductile detailing requirements
• Tall building systems: Tube, bundled tube, diagrid, outrigger-braced core — tested in the context of specific famous towers
• GATE AR exam: MCQ — load classification; structural system identification; NAT — bending stress, truss member force, moment calculation

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H. Common Confusions

• Windward = suction, leeward = pressure — Reversed. Windward face = positive pressure (wind pushes in). Leeward face = negative pressure / suction (wind pulls awa…
• Roof slope < 30° has wind pressure on windward slope — Wrong. IS 875 Part 3: windward roof slopes less than 30° experience suction (negative pressure), not pressure. P…
• Point load formula Mmax = wL²/8 — wL²/8 applies to UDL only. For a point load P at midspan: Mmax = PL/4. For P at any point: Mmax = Pab/L. Mixing these is…
• Infill brick wall = load-bearing wall — Infill walls in RC frames are non-structural. They do NOT carry floor/roof loads. They add stiffness (can attract seismi…
• Snow load applies across India — IS 875 Part 4 snow loads are relevant only in hill-station regions (Himalayas, parts of NE India). Applying snow load to…
• Slenderness ratio = Height / Width — λ = Le/r, not L/b. The denominator is the radius of gyration r = √(I/A), not the width. Using width directly gives a…

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I. Compare & Contrast

Parameter	Framed Tube	Bundled Tube
Principle	Façade = structural tube; columns + deep spandrels	Multiple tubes bundled; floor plans vary by height
Shear lag	Present; corner columns overstressed	Reduced by internal webs
Height capacity	60–100+ storeys	100+ storeys
Famous example	World Trade Center, New York	Willis Tower (Sears), Chicago
Structural engineer	Fazlur Rahman Khan	Fazlur Rahman Khan (SOM)

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J. Memory Hooks

• Dead = Permanent (DL); Live = Variable (LL); Wind + Seismic = Lateral loads
• Soft storey = shear failure = stiffness < 70% of storey above (IS 13920)
• Zero force member: at a joint with 2 non-collinear members and no external load → both are zero force
• Bundled tube = Sears/Willis Tower (Fazlur Rahman Khan, SOM)
• SFD / BMD: SFD integral = BMD; peak moment at zero shear point
• GATE 2025 Q61 (Ans: A) — bundled tube tall buildings

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K. Revision Ladder

Step	What to revise	Exam relevance
1	Load types: DL, LL, wind, seismic; IS 875 values; load combinations	GATE MCQ
2	Truss analysis: zero force members; method of joints; method of sections	GATE NAT — 2022 Q56 (Ans: 0.0)
3	SFD and BMD: simply supported beam under UDL; point load; overhang	GATE NAT — 2024 Q43; 2025 Q62; 2026 Q63
4	Bending stress: σ = M·y/I; I-beam bending stress NAT	GATE NAT — 2021 Q50 (Ans: 150)
5	Soft storey: definition; stiffness < 70%; seismic vulnerability	GATE MCQ — 2021 Q24 (Ans: B)
6	Tall structure systems: framed tube, bundled tube, outrigger, diagrid	GATE MCQ/MSQ
7	GATE AR 2021 Q36 (Ans: D — structural systems); GATE AR 2025 Q55 (Ans: A,B — pile types)	PYQ review

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L. Exam Traps

Trap	Incorrect Belief	Correct Principle
Windward = suction, leeward = pressure	Common misconception about windward = suction, leeward = pressure	Reversed. Windward face = positive pressure (wind pushes in). Leeward face = negative pressure / suction (wind pulls away). Both sides contribute to net lateral force.
Roof slope < 30° has wind pressure on windward slope	Common misconception about roof slope < 30° has wind pressure on windward slope	Wrong. IS 875 Part 3: windward roof slopes less than 30° experience suction (negative pressure), not pressure. Pressure occurs only when slope > 30°. This governs uplift design of shallow-pitch roofs.
Point load formula Mmax = wL²/8	Common misconception about point load formula mmax = wl²/8	wL²/8 applies to UDL only. For a point load P at midspan: Mmax = PL/4. For P at any point: Mmax = Pab/L. Mixing these is the single most common numerical error.
Infill brick wall = load-bearing wall	Common misconception about infill brick wall = load-bearing wall	Infill walls in RC frames are non-structural. They do NOT carry floor/roof loads. They add stiffness (can attract seismic force unpredictably) but are not designed as structural members. Treating them as load-bearing overestimates capacity and misjudges failure mode.
Snow load applies across India	Common misconception about snow load applies across india	IS 875 Part 4 snow loads are relevant only in hill-station regions (Himalayas, parts of NE India). Applying snow load to buildings in Chennai, Mumbai, or Delhi is incorrect.
Slenderness ratio = Height / Width	Common misconception about slenderness ratio = height / width	λ = Le/r, not L/b. The denominator is the radius of gyration r = √(I/A), not the width. Using width directly gives an incorrect (usually lower) result.
Wind and seismic loads are combined in the governing combination	Common misconception about wind and seismic loads are combined in the governing combination	IS 1893 Cl. 6.3.1.2 explicitly states wind and seismic forces need NOT be combined. Design for the more critical of the two independently.
Higher stiffness means lower load	Common misconception about higher stiffness means lower load	Stiffer elements attract more load (load proportional to stiffness in a parallel system). A shear wall added to a frame takes a disproportionate share of lateral load precisely because it is stiffer.
Le for a cantilever column = L	Common misconception about le for a cantilever column = l	For a fixed-base, free-top cantilever: Le = 2L. This effectively doubles the slenderness ratio compared to a pinned-pinned column of the same height — critical for isolated ground-floor columns in stilt buildings.
IS 875 Part 5 covers seismic loads	Common misconception about is 875 part 5 covers seismic loads	IS 875 Part 5 covers special loads and load combinations (thermal, erection, etc.). Seismic loads are covered exclusively by IS 1893:2016. Selecting IS 875 for seismic is a standard MCQ trap.

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M. Answer-Writing Cues

NAT (beam moment):

MCQ (IS 875):

Slenderness NAT:

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N. PYQ Integration (2007–2026 verified)

Topic	Exam Appearance	Question Pattern
Topic	Exam appearance	Pattern
IS 875 part ID	Frequent MCQ	Match load type to Part 1–5
Point load vs UDL	NAT / MCQ	PL/4 vs wL²/8 confusion
Wind roof suction	MCQ / MSQ	Slope threshold 30°
Slenderness λ	NAT	Le/r with effective length factors
Infill vs load-bearing	MSQ trap	Frame infill not in gravity path
GATE AR 2021 Q24 — Ans: B	MCQ	Soft storey failure during earthquake — cause identification
GATE AR 2021 Q34 — Ans: D	MCQ	Match column elements — topmost horizontal / vertical members
GATE AR 2021 Q36 — Ans: D	MCQ	Match buildings with structural systems — Empire State, John Hancock
GATE AR 2021 Q50 — Ans: 150	NAT	Simply supported steel I-beam — bending stress calculation NAT
GATE AR 2022 Q56 — Ans: 0.0	NAT	Hypothetical truss — zero force member identification NAT
GATE AR 2024 Q43 — Ans: 9.9–10.1	NAT	Overhang beam — maximum hogging moment NAT
GATE AR 2025 Q34 — Ans: B	MCQ	See-saw static equilibrium about fulcrum — applied force
GATE AR 2025 Q55 — Ans: A,B	MSQ	Examples of Concrete Cased Pile MSQ
GATE AR 2025 Q61 — Ans: A	MSQ	Tall buildings with bundled-tube structural system MSQ
GATE AR 2025 Q62 — Ans: 48	NAT	Simply supported beam under UDL — shear/deflection NAT
GATE AR 2025 Q63 — Ans: 160–180	NAT	Rectangular RCC beam — moment of resistance NAT
GATE AR 2026 Q63 — Ans: 5.10–5.50	NAT	Overhang beam ABC under UDL — reaction/moment NAT

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O. Mini-Check — Lesson 8.1

Q. Beam Bending Moment

A simply supported beam of span 8 m carries a UDL of 15 kN/m (total, unfactored). Applying load factor 1.5, the factored maximum bending moment in kN·m is ____.

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Q. Column Slenderness Ratio

A square RC column (250 mm × 250 mm) has an effective length of 3.5 m. The slenderness ratio λ is ____.

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Q. Load Types

Which of the following are classified as dynamic loads? Select all that apply.

(A) Dead load from RCC slab
(B) Seismic inertial force
(C) Wind load as per IS 875 Part 3 (when flutter governs)
(D) Imposed load from office occupants
(E) Impact load from elevator machinery
(F) Snow load on a roof in Shimla

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Q. IS 875 Part Identification

The design wind pressure on a building facade is governed by:

(A) IS 875 Part 1
(B) IS 875 Part 2
(C) IS 875 Part 3
(D) IS 1893:2016

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MCQ — Load Combination

For a residential ground-floor beam where wind and seismic are negligible, the governing limit-state combination per IS 456 is:

(A) 1.2 DL + 1.2 LL + 1.2 WL
(B) 1.5 DL + 1.5 LL
(C) 0.9 DL + 1.5 EL
(D) 1.5 DL + 1.5 EL