Engineering Flashcards by Cooper Tran

Scalar

Quantities which have size but no direction.

e.g. $40, 60 seconds, 3kg

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force vector quantity (4 properties).

Magnitude: Strength or intensity of the force (measured in N or lbf).

Sense: Orientation in which the force is applied. (arrow)

Direction: The orientation in which the vector points. (acute angle of horizontal)

Point of Application: Specific location where the force is exerted on an object.

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co-linear force

The line of action of all the forces acts along the same line.

Example: Tug of war

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concurrent force

Multiple forces applied to a single point and intersect at the one point.

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Co-planar force.

Forces acting in the same plane or on the same two-dimensional surface.

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four type of beam supports.

Fixed

Roller

Simple Support

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Describe what a fixed beam support does

Offers resistance against vertical and horizontal movement as well as rotation.

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Describe what a Roller beam support does

Provides vertical support while allowing horizontal movement, but prevents rotation.

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Describe what a Pin beam support does

Allows rotation but restrains horizontal and vertical movement.

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Describe what a Cantilever beam support does

A cantilever beam fixed at one end and free at the other is a structural element that offers support against vertical loads and moments at its fixed end while allowing rotation and limited lateral movement at its free end.

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Define equilibrium in relation to structures.

When all forces or moments acting upon it are balanced.

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What is a moment?

Also known as torque, is a measure of the rotational force applied to an object about a specific point.

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How do you calculate a moment?

= force x perpendicular distance from pivot (M = fd)

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What are the types of bridges?

Beam, Arch, Suspension, Cable-Stayed, Truss

BASCT

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Describe a truss structure

A truss is a rigid framework with internal members that are connected in a triangular pattern.

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Identify the typical component parts of a truss bridge

Top Chord and Bottom Chord
Deck
Vertical
Diagonal
End post
Hip vertical
Support (abutment)

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Types of truss bridges

Warren /\/\/\
Pratt \ \ / /
Howe / / \ \

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What is compression ?

A type of force or stress that tends to shorten or squeeze an object along its axis.

It occurs when external forces push or press against the object’s structure, causing its particles or components to move closer together.

Commonly experienced by columns and beams

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What is tension?

A type of force or stress that tends to elongate or stretch an object along its axis.

It occurs when external forces pull or stretch the object’s structure, causing its particles or components to move farther apart.

Commonly experienced by cables and ropes

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In a truss bridge, what type of force is experienced by the top chord

Compressive forces

Benefits of a Truss compared to other bridge types

Efficient use of materials: triangular shapes allow for optimal strength to weight ratio.

Span large distances: Suitable for long spans without the need for intermediate supports.

Versatility: Can be constructed using various materials, such as steel, wood, or concrete.

Ease of inspection and maintenance: Clear visibility of members simplifies inspection and repair processes

Aesthetic appeal: Offers architectural flexibility and can be designed with visually appealing feature

In a truss bridge, what type of force is experienced by the bottom chord

tensile forces

Vector

Show both direction and magnitude.

e.g force, acceleration, velocity and displacement

Can be represented graphically

written with bar above pronumeral

Newton’s first law of motion

an object in motion will remain in motion unless acted upon by another force

Newton's Second Law

Force = mass x acceleration

Newton's Third Law

For every action there is an equal and opposite reaction

In a cable stayed bridge where are compression and tensile forces located

Compressive = towers Tensile = cables

In a beam bridge where are compression and tensile forces located

Compressive = Piers, top of beam Tensile = bottom of beam

In an arch bridge where are compression and tensile forces located

Compressive = abutments Tensile = None

Addition of vectors: Sign of Vectors

Must be given sign because they have direction Given positive or negative depending on direction of vector Resultant (sum of all forces) = closing force which goes in opposite general direction to the other forces

A beam may be subjected to:

Concentrated loads. Distributed loads or a combination of both

What is a simply support beam

Pinned at one end and roller support at the other

Overhanging beam

Rests on two similar supports to the simply supported arrangement but extends beyond one or both of its supports.

What are the characteristics of cantilever

Rigidly fixed at one end and free at the other.

A pinned supports reactions can be unknown. Therefore it is analyzed in terms of its:

horizontal and vertical components

The total reaction of at the fixed end of a cantilever bean may contain.

Horizontal reaction force Vertical Reaction Force Reaction moment (3 unknowns at fixed end)

Conditions of equilibrium

∑FH = 0 ∑FV = 0 ∑M = 0

Pins

Pins are typically small, cylindrical rods or bars made of steel or other strong materials. They are used in structural connections to transfer loads, provide support, or allow for movement between connected members.

Abutments

Foundations that support weight of bridge and hold back soil - typically made of concrete

Piers

Additional supports in the middle of bridges

Describe how you could find a zero Force Members

If a joint only has two non-colinear members and there is no external load or support reaction at that joint, then those forces are zero force members. If three members form a truss joint for which two of the members are colinear and there is no external load or reaction at that joint, then the third non-colinear member is a zero-force member.

Determinacy of Coplanar Trusses

b + r = 2j (Determinate) b + r > 2j (Indeterminate) b = num of bar members r = number of reactions J = number of joints

What is magnitude in relation to force vector quantity

Strength or intensity of the force (measured in N or lbf).

What is sense in relation to force vector quantity

Orientation in which the force is applied. (Shown by an arrow)

What is direction in relation to force vector quantity

The orientation in which the vector points. (acute angle of horizontal)

What is Point of application in relation to force vector quantity

Specific location where the force is exerted on an object.

Gusset plate

Gusset plates, typically triangular or rectangular steel plates, reinforce and connect structural elements at joints where beams, columns, or trusses intersect, providing added support and stiffness through bolting or welding.

What is a simple support used for?

Simple supports aren’t widely used in real-life structures unless the engineer can be sure that the member will not translate; otherwise, they run the risk of the member simply falling off the support.