Loadbearing Construction Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following building types would be most suitable for loadbearing construction, as described in the text?

Office buildings with flexible floor layouts and open spaces

Apartment buildings with numerous small rooms and repetitive floor plans (correct)

Single-family homes with large open floor plans

Industrial buildings with heavy machinery and wide spans

What key structural element is mentioned as a significant factor in providing lateral rigidity to a loadbearing masonry building?

Stair wells and lift shafts (correct)

Steel beams

Interior columns

Exterior cladding

The text suggests that a well-designed loadbearing masonry building should have _______.

A minimal number of internal walls

A highly symmetrical wall arrangement

A dominant wall orientation in one direction only

A balanced distribution of walls in different directions (correct)

What is the primary function of corridor walls in a simple cross-wall structure?

Contributing to the building's longitudinal stability (B) Signup and view all the answers

Why are highly unsymmetrical wall arrangements in loadbearing masonry buildings generally discouraged?

They may lead to unpredictable stress distributions under lateral loads (A) Signup and view all the answers

Which of the following describes a cellular wall system?

A structure with loadbearing walls arranged in a grid-like pattern (A) Signup and view all the answers

What is the main advantage of using loadbearing construction for buildings like hostels, hotels, and flats?

It maximizes the use of space and allows for a variety of room layouts (B) Signup and view all the answers

What is a defining characteristic of a unit categorized as a block in masonry?

It exceeds at least one of the dimensions specified for bricks. (D) Signup and view all the answers

Which category of bricks is specifically defined by BS 3921 as suitable for exterior and interior walls?

Facing bricks (C) Signup and view all the answers

Which type of brick is designed to withstand extreme conditions of exposure to water and freeze-thaw cycles?

Frost resistant (F) (C) Signup and view all the answers

What must bricks be free from to conform to acceptable standards?

Deep cracks and damage to edges (C) Signup and view all the answers

How are engineering bricks characterized compared to common bricks?

They have higher compressive strength and lower absorption limits. (C) Signup and view all the answers

What is the primary composite material that makes up mortar in masonry?

Cement, lime, and sand (D) Signup and view all the answers

Which of the following standards pertains to calcium silicate bricks?

BS 187 (A) Signup and view all the answers

Which type of brick is suitable for use only in internal conditions due to its low frost resistance?

Not frost resistant (O) (A) Signup and view all the answers

What are common bricks primarily used for in construction?

General building work (C) Signup and view all the answers

What is the impact of not filling bed joints in brickwork?

It can decrease the strength of brickwork by as much as 33%. (D) Signup and view all the answers

Which aspect of brickwork is affected by failure to fill vertical joints?

Flexural resistance. (C) Signup and view all the answers

What is a common reason for gaps in mortar beds during brickwork construction?

Carelessness or haste in the workmanship. (A) Signup and view all the answers

What is the primary concern related to unfilled perpendicular joints in brickwork?

They can indicate careless workmanship and affect weather exclusion. (C) Signup and view all the answers

How can the reliability of masonry compare to that of concrete?

Masonry can be made as reliable as concrete with proper supervision. (A) Signup and view all the answers

How does the position of units (laid on edge or on end) affect masonry strength?

It decreases strength compared to normal bed faces. (A) Signup and view all the answers

What is the effect of using a highly perforated unit in masonry construction?

It likely leads to lower strength when compressed parallel to its length. (D) Signup and view all the answers

What is unique about the strength consideration for hollow block masonry?

Strength depends on whether cores are filled or unfilled. (C) Signup and view all the answers

How should the strength of full-bedded blocks be calculated?

Based on the maximum test load divided by the gross area. (B) Signup and view all the answers

What happens when the cores of hollow blocks are filled with concrete?

It leads to unpredictable differences in lateral strains. (D) Signup and view all the answers

How should masonry strength be assessed when units are not laid on their normal bed faces?

There is no general rule for assessment. (D) Signup and view all the answers

What is a significant challenge when calculating the strength of masonry with filled hollow blocks?

Differences in strain behaviors can lead to variability. (D) Signup and view all the answers

What is the likely outcome when masonry is built and stressed in directions other than normal?

There is a substantial reduction in strength. (A) Signup and view all the answers

What does shell-bedded masonry strength depend on?

The mortared area of the units. (D) Signup and view all the answers

What overarching factor contributes to masonry strength according to construction parameters?

Type and position of the units used in construction. (C) Signup and view all the answers

What is the maximum allowed volume of perforations in a perforated brick?

25% (D) Signup and view all the answers

Which type of brick is not covered by the British Standards described in the text?

Glass bricks (C) Signup and view all the answers

What is the minimum average compressive strength of a concrete brick?

21 N/mm² (B) Signup and view all the answers

Which of the following brick types is suitable for use in a low-rise building?

Bricks with compressive strength of 5.2 N/mm² (B) Signup and view all the answers

What is the maximum allowable volume of depressions (frogs) in a brick?

20% (B) Signup and view all the answers

Which type of bricks require the least amount of soluble salt content?

Low (L) bricks (B) Signup and view all the answers

What is the primary factor that determines the suitability of a brick for structural purposes?

Its compressive strength (A) Signup and view all the answers

Which of the following is a type of brick covered by BS 4729?

Standard special bricks (D) Signup and view all the answers

Which type of brick is most likely to be used in a reinforced or prestressed brickwork?

Bricks with a compressive strength of 20 N/mm² or higher (D) Signup and view all the answers

Which of the following statements about concrete blocks is inaccurate?

They are covered by BS 3921. (B) Signup and view all the answers

What is the primary concern regarding clay bricks in terms of weather conditions?

They can be damaged by freezing and thawing. (A) Signup and view all the answers

Study Notes

Design of Masonry Structures

Third edition of Load Bearing Brickwork Design
Authors: A.W. Hendry, B.P. Sinha, and S.R. Davies
Publisher: E & FN Spon, an Imprint of Chapman & Hall

Advantages and Development of Loadbearing Masonry

Basic advantage: Masonry is a versatile material for performing various building functions in one element, unlike steel-framed buildings.
Functions: Structure, space subdivision, thermal & acoustic insulation, and weather protection.
Cost-effectiveness: Masonry is relatively cheap with acceptable finishes.
Flexibility: Adaptable to different building layouts.
Historical shift: Brick construction for multi-story buildings declined in the first half of the 20th century, replaced by steel and reinforced concrete.
Improvements: Structural codes after 1950 allowed more rational calculation of wall thickness and masonry strengths.

Basic Design Considerations

Suitable for buildings with repeated floor plans and numerous small to medium-sized rooms.
Crucial factors for layout: A balance in the orientation of walls to resist lateral forces and appropriate consideration of stair wells, lift shafts, and service ducts.
Wall Arrangement Types:
- Cellular systems: Internal and external walls creating a cellular pattern in plan.
- Simple/Double cross-wall systems: Bearing walls at right angles to the building's longitudinal axis, with longitudinal stability provided by corridor walls.
- Complex arrangements: A combination of cellular and cross-wall systems.

Structural Safety: Limit State Design

Goal: Fundamentally stable and robust buildings.
Design approach: Qualitative and conceptual measures to ensure structural performance in resisting service loads.
Quantification: Quantitative approach relating load estimates to material strength and rigidity is crucial for optimal design.
Lifetime performance: Ensure intended function without significant deflection, cracking, or collapse within the building's lifetime.
Recognising uncertainties: Acknowledges the inherent uncertainty in service loads, material properties, and load-strength relations.
Limit state design: Design to satisfy specific criteria for strength and serviceability, considering uncertainties in loading, strength, and analysis.

Foundations

Stiffness and deflection limitations: Studies of existing loadbearing masonry buildings suggest constraints on relative deflection (in relation to the length of deflected parts) for various types of soil configurations.
Settlement limits: The average settlement of brickwork structures should not exceed 150 mm (depending on the rate of settlement and masonry characteristics).
Foundation depth: In clay soils, foundations should be at least 1 metre deep to avoid moisture fluctuations.
High-rise masonry buildings often use reinforced concrete rafts (typically 600mm thick).

Reinforced and Prestressed Masonry

Extending the application of masonry: Using reinforcement and prestressing techniques enhances masonry's capabilities.
Techniques:
- Embedding bars in bed/collar joints, pockets in masonry using suitable bonding patterns, and placing steel in cavities formed by two leaves or wythes of brickwork (grouted cavity construction).
Additional benefits: Cost savings by eliminating shuttering operations and attractiveness of exposed masonry walls.

Bricks, Blocks and Mortars

Material classes: Bricks are categorised into common, facing, and engineering bricks, defined by standards like BS 3921, 187, and 6073.
Classification: Defined sizes (mm) according to standard specifications.
Materials: Clay, calcium silicate, or concrete.

Brick Varieties

Frost resistance classification: Frost resistant (F), Moderately frost resistant (M), and Not frost resistant (O) categories.
Soluble salt content: Low (L), and Normal (N) categories.
Types of bricks: Plain cellular, perforated wire cut, pressed engineering, pressed brick with frogs, and solid wire cut.

Compressive Strength

Strength factors: Geometry, bond, stress raisers, water-cement ratio, mix types and structural design influence strength considerably.
Design considerations: The strength of the masonry in combined shear and compression.
Tests and design: Empirical relationships between unit, mortar, and masonry strengths.

Stress-Strain Properties

Linear elastic: Masonry generally treated as a linear elastic material, though stress-strain curves exhibit parabolic nature under service conditions.
Young's Modulus: Approximated as Ε = 700σ' where σ' is the crushing strength of the material and E is the elastic modulus. The estimated values are valid for 85 to 80% of the ultimate strength.

Workmanship Effects

Workmanship impact: Craftsmanship directly affects masonry strength.
Deficiencies:
- Incomplete bed joint filling
- Excessive bed joint thickness
- Deviation from verticality for plumb walls
- Excessive heat/cold when in construction
- Variations in moisture content, including improper curing process
Consequences: Reduced strength, cracking, and instability.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on loadbearing construction concepts, including suitable building types and key structural elements. This quiz covers essential aspects such as lateral rigidity, wall arrangements, and the advantages of using loadbearing masonry in various types of buildings.