Types and Design of Structures

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Questions and Answers

What is the main characteristic of a mass structure?

It relies on external supports to maintain stability.

It is designed for low cost and ease of assembly.

It uses lightweight materials to reduce overall weight.

It is made by piling or stacking similar materials. (correct)

Which type of structure utilizes a skeleton frame to support weight?

Shell structure

Liquid structure

Mass structure

Frame structure (correct)

What is a primary advantage of shell structures?

They are the cheapest option available.

They are easy to construct and disassemble.

They can carry heavy loads without any materials.

They distribute forces evenly across their surface. (correct)

Which aspect is NOT considered when describing structures?

Popularity Signup and view all the answers

Which of the following is a primary function of structures?

Supporting a load or transporting materials. Signup and view all the answers

What is a composite material?

Materials combined to enhance strength and limitations. Signup and view all the answers

Why is the aesthetic aspect of structures important?

It enhances the appearance and public perception. Signup and view all the answers

What must be matched to the purpose of the structure?

Material properties and characteristics Signup and view all the answers

What type of joint requires lubrication to allow movement?

Mobile joints Signup and view all the answers

What unit is used to measure force?

Newton (N) Signup and view all the answers

Which type of load is characterized by its non-permanent nature?

Dynamic load Signup and view all the answers

In which situation do particles separate, leading to potential structural failure?

Shear Signup and view all the answers

How can the strength of a structure be enhanced using design techniques?

By adding braces to form triangles Signup and view all the answers

What is the effect of using friction in structural designs?

Helps stabilize structures Signup and view all the answers

What happens to a structure under repeated stress, causing cracks?

Metal fatigue Signup and view all the answers

What happens to a structure when its center of gravity shifts outside its base?

It becomes unstable and at risk of collapse. Signup and view all the answers

Which structural feature uses a central keystone for added strength?

Arches Signup and view all the answers

Which type of structure relies primarily on its own weight for stability?

Mass Structure Signup and view all the answers

Which of the following joints allows movement in a structure?

Hinges Signup and view all the answers

What is a crucial factor for ensuring a structure's stability?

Construction materials used Signup and view all the answers

What characterizes a shell structure?

It uses a thin, shaped outer layer for strength. Signup and view all the answers

What are manufactured structures usually modeled after?

Natural structures Signup and view all the answers

Which of the following describes the concept of 'margin of safety' in structures?

Ensuring reliability and safety for long-term use. Signup and view all the answers

What is the importance of a firm foundation in structures?

To ensure it stands on solid ground. Signup and view all the answers

What is the primary difference between weight and mass?

Weight changes with location, while mass is constant. Signup and view all the answers

Which type of load is considered non-permanent and can change over time?

Live Load Signup and view all the answers

What type of internal force involves a twisting action?

Torsion Signup and view all the answers

What is a common solution to frame structures push or pull out of shape?

Implementing braces to form rigid triangles Signup and view all the answers

Which principle of stability focuses on maintaining balance around a central point?

Center of Gravity Signup and view all the answers

What type of failure occurs when particles slide apart due to stress?

Shear Failure Signup and view all the answers

Which method is NOT considered a key method for designing with forces?

Increase weight in structure Signup and view all the answers

What structural problem arises from weak foundations?

Instability Signup and view all the answers

Study Notes

Types of Structures

Structures are objects with a defined shape and size, serving a specific function.
Every part of a structure must support forces (pushes or pulls) to prevent damage or instability.
Structures are classified as natural or manufactured.
Natural structures occur naturally in the environment.
Manufactured structures are often modeled after natural structures.

Structure Design

Design includes shape, size, and materials.
Three structural design types: mass, frame, and shell structures.
Mass structures are built by piling or stacking similar materials, offering strength from their weight.
Frame structures feature a supporting skeleton of materials, covered differently; load-bearing walls support the structure, while partition walls do not. Frame structures are commonly used in construction.
Shell structures are thin, shaped outer layers that enclose and support, distributing forces evenly. They can be susceptible to failure if the outer layer has imperfections.

Describing Structures

Crucial areas to consider include function, aesthetics, safety, materials, and construction.
Function: what the structure is used for (supportive of loads, enclosing a space, or transporting items).
Aesthetics: the structure's appearance (shape, texture, color, simplicity, and symmetry).
Safety: the structure's reliability and ability to withstand expected use to protect people.
Materials: specific properties of each material which may limit or enhance the structure. Composite materials combine unique material strengths. Woven or knit materials increase strength via fibers.
Construction: how the structure is put together (fastened or connected). Structures need adequate safety margins to sustain use as expected over long periods.

Mass and Forces

Mass is the number of particles in a substance, measured in kilograms or grams.
A balance is used to compare an object's mass to a known standard.
Force is measured in Newtons (N). A force meter measures the force of gravity on a mass.
Weight is the gravitational force between two objects, dependent on their masses and distance. Mass is the material in an object, and weight is the gravitational force on that object.

Forces, Loads, and Stresses

Loads are forces on a structure.
External forces are permanent (dead load), non-permanent (live load), and from impacts.
Internal forces include tension (pulling), compression (pushing), torsion (twisting), and shear (sliding).
Resistance to stress includes tensile strength (resistance to stretching), compressive strength (resistance to compression), and shear strength (resistance to shearing).

How Structures Fail

Material failure types include shear (particles separating), bending/buckling (compression causing deformation) and torsion (damaging internal integrity). Metal fatigue can result from repeated stresses, causing cracks over time.

Designing with Forces

Distributing the load, directing forces along angled components, and designing with appropriate material shapes (especially triangles) are key methods of design.
Various solutions address structural problems like structural weakness or instability concerning bending or shape. This includes adding braces for rigid triangles, different shapes like I-beams, and using layers or pilings for stable foundations.

Stable Structures

Stability focuses on balancing forces, locating the center of gravity, ensuring that thrust forces remain within the base of the structure, and establishing symmetry in mass distribution in the structure design to prevent collapse.
Firm foundations are critical for stability, distributing loads over a large area.
Other stability factors include rotational speed for some structures and frictional forces stabilizing the structure in external forces.

Beams

Beams, typically cylindrical or hollow, maximize efficiency due to their use of friction to stop structure movement and resist sliding.

Additional Information

Mobile joints allow movement, lubricated to ensure movement and efficiency.
Rigid joints are fixed connections using fasteners, interlocking shapes, adhesions, or melting/welding together.

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Description

This quiz covers the essential concepts of structure types and their design criteria. It explores natural and manufactured structures, along with the three main types of structural designs: mass, frame, and shell. Test your understanding of how these structures function and their characteristics.