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Structural Components

6 questions

All types6Multiple choice3True / False2Matching1
Question 1Question →

A vertical column in a building framework is primarily designed to resist tensile forces that attempt to stretch it.

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Answer: False

Answer

False
The statement is false because vertical columns bear the downward weight of a structure, subjecting them to compressive forces (pushing or squeezing) rather than tensile forces (pulling or stretching). Structural members primarily designed for tension are typically known as ties or cables.

Step-by-Step Solution

1
Identify the structural component and its primary function.
The component in question is a vertical column, which supports the heavy weight of the building framework directly above it.
Understanding the component's physical role dictates the type of force it experiences.
2
Determine the type of internal force caused by this load.
Weight pushing down on a vertical support creates compression (pushing the material together), not tension (pulling the material apart).
Tensile forces stretch a material, while compressive forces squeeze it.

Key Concept

Tension vs. Compression in Structural Members
Estimated Time:30s
Question 2Question →

Match each basic structural component with its primary function and the main type of internal force it is designed to resist.

Click a left item, then click its matching right item

Items

Column
Beam
Tie
Strut

Matches

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Answer

Column matches with the vertical compressive member. Beam matches with the horizontal bending member. Tie matches with the tensile member. Strut matches with the compressive framework member.
Each structural component serves a distinct mechanical role based on orientation and force distribution. Columns handle vertical compression, beams handle transverse bending, ties handle axial tension, and struts handle axial compression.

Step-by-Step Solution

1
Identify the primary orientation and force resisted by a Column.
A Column is a vertical member supporting heavy compressive loads.
Columns transfer the weight of the structure above down to the foundation through compression.
2
Identify the primary orientation and force resisted by a Beam.
A Beam is a horizontal member resisting bending forces.
Beams span open spaces and carry downward loads across their span, which induces bending.
3
Distinguish between a Tie and a Strut based on internal forces.
A Tie resists tension (pulling apart), while a Strut resists compression (pushing together).
Ties 'tie' things together to prevent separation. Struts act like rigid pillars holding things apart.

Key Concept

Basic Structural Components and the Internal Forces They Resist
Estimated Time:1m 0s
Question 3Question →

A horizontal shelf is attached to a vertical wall. To safely hold a heavy box placed on the outer edge, a straight diagonal wooden strut is installed underneath, connecting the outer edge of the shelf to a lower point on the wall. When the heavy box is placed on the shelf, what primary type of structural force acts along the length of the diagonal strut?

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Answer: Compression

Answer

Compression
The correct answer is Compression because the diagonal strut acts as a prop to hold the shelf up. The weight of the box pushes down on the shelf, which in turn presses down onto the top end of the strut, squeezing it against the wall. A force that squeezes or crushes a structural member is called compression.

Step-by-Step Solution

1
Analyze the direction of the load applied to the structural system.
The heavy box applies a downward force on the outer edge of the horizontal shelf.
Understanding the source and direction of the applied load is required to determine how individual components react.
2
Determine how the downward force interacts with the diagonal strut.
The shelf transfers the downward force into the top of the diagonal strut, pushing it into the wall at the bottom.
Tracing the load path reveals whether a member is being stretched, crushed, or twisted.
3
Identify the specific type of internal force resulting from this interaction.
The strut is being squeezed or crushed inward from both ends, which defines compression.
Axial forces that push the ends of a structural member toward each other are compressive forces.

Key Concept

Tension and Compression in Structural Members
Estimated Time:45s
Question 4Question →

A vertical communications mast features a rigid horizontal steel cross-arm extending outward to support a heavy dish antenna at its far end. To support the load, a diagonal steel cable connects the outer tip of the cross-arm to an anchor point higher up on the main mast. Assuming the weight of the cross-arm itself is negligible compared to the antenna, which of the following best describes the primary internal forces experienced by these two structural components?

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Answer: The cross-arm experiences compression, and the diagonal cable experiences tension.

Answer

The cross-arm experiences compression, and the diagonal cable experiences tension.
The correct answer accurately applies static equilibrium to the joint supporting the antenna. The heavy antenna pulls straight down. To counteract this, the diagonal cable must pull diagonally upward and inward toward its anchor point on the mast. Because the cable pulls on the joint, it is in tension. However, this inward pull from the cable would drag the antenna toward the mast if unopposed. The rigid horizontal cross-arm prevents this by pushing outward against the joint. Because the cross-arm is being squeezed between the mast and the inward-pulling cable, it is under compression.

Step-by-Step Solution

1
Analyze the forces acting on the joint at the outer tip of the cross-arm.
There is a downward force from the weight of the antenna.
Identifying the applied external load is the first step in finding internal forces.
2
Determine how the diagonal cable responds to the downward load.
The cable must pull upward to prevent the antenna from falling. Since it attaches higher up on the mast, its pull is directed upward and inward along its length.
Cables can only pull (tension); they cannot push.
3
Resolve the cable's tension force into vertical and horizontal components.
The upward vertical component supports the antenna's weight. The horizontal component pulls the joint inward toward the mast.
Vector resolution helps determine the effect of the cable on the horizontal cross-arm.
4
Analyze the horizontal cross-arm's response to the cable's inward pull.
To keep the joint stationary (in equilibrium), the cross-arm must push outward against the inward pull of the cable. A member that pushes outward at its ends is under compression.
Newton's laws of motion dictate that all forces at a stationary joint must sum to zero.

Key Concept

Vector resolution and equilibrium in truss-like structures determine whether a member is in tension or compression.
Question 5Question →

A standard derrick crane lifts a heavy shipping container. The crane consists of a vertical rigid mast anchored to a ship's deck, a rigid steel boom extending outward and upward from the base of the mast, and a horizontal steel cable connecting the top of the mast to the upper tip of the boom. The container hangs vertically from the upper tip of the boom. Under the downward weight of the container, what primary internal structural forces are experienced by the horizontal steel cable and the rigid steel boom, respectively?

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Answer: The horizontal cable experiences tension, and the rigid boom experiences compression.

Answer

The horizontal cable experiences tension, and the rigid boom experiences compression.
The correct answer accurately identifies that cables can only stretch (putting them in tension) to keep the structure from collapsing, while the rigid boom acts as a column holding up the weight, which squeezes it (putting it in compression).

Step-by-Step Solution

1
Analyze the forces acting at the tip of the boom.
Three forces meet at the tip: the downward weight of the container, the horizontal force from the cable, and the angled force from the boom.
Identifying the junction point allows for force balancing (equilibrium).
2
Determine the state of the horizontal steel cable.
The cable prevents the boom from falling outward and downward. To hold the boom back, the cable must pull inward, meaning it is being stretched.
A stretched structural member is experiencing tension.
3
Determine the state of the rigid steel boom.
The boom pushes upward and outward against the downward pull of the load and the inward pull of the cable. The weight pushes down into the length of the boom.
A structural member that is being pushed or squeezed from its ends is experiencing compression.

Key Concept

Tension and Compression in Structural Members
Question 6Question →

In a tied-arch bridge assembly (often called a bowstring arch), the horizontal structural member connecting the lower ends of the arch primarily functions as a compression strut to prevent the ends of the arch from collapsing inward under a heavy downward load.

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Answer: False

Answer

False
The statement is false because the horizontal member in a tied-arch bridge must resist the outward thrust of the arch. Therefore, it pulls inward and is subjected to tension, functioning as a tie rather than a compression strut.

Step-by-Step Solution

1
Analyze the load distribution and reaction forces in a standard arch structure.
When a downward vertical load is applied to an arch, the geometric shape redirects the forces along its curve, resulting in a strong outward horizontal thrust at the base supports.
Understanding the fundamental directional forces generated by an arch is necessary to determine what counter-forces are required for equilibrium.
2
Determine the required structural function of the horizontal connecting member.
Because the ends of the arch naturally tend to push outward away from each other, the horizontal member connecting them must actively pull inward to hold the ends together.
Structural components in a stable assembly must provide reaction forces that directly oppose the applied loads.
3
Identify the type of internal stress created in this horizontal member.
A structural member that pulls inward against an outward spreading force is being stretched. This means it experiences tensile stress, acting as a tie.
This confirms the member acts as a tension tie, directly contradicting the claim that it is a compression strut.

Key Concept

Tension and Compression in Arch Structures
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