Exam 2 Flashcards

1
Q

Space frame

A

three-dimensional trussed system spanning in two directions where members are in tension or compression only.

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2
Q

What are the two most widely used polyhedral modules (shapes) for building space frames?

A

half-octahedron and tetrahedron

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2
Q

What do space frames consist of?

A

identical repetitive module, with parallel upper and lower layers (which correspond to the chords of trusses)

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3
Q

How is labor cost for space frames affected by changes in module size?

A

Labor costs increase as module sizes decrease and decrease as module sizes increase

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4
Q

What does a half octahedron look like?

A

An equilateral pyramid with a SQUARE base

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5
Q

What does a tetrahedron look like?

A

A pyramid with a TRIANGULAR base

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6
Q

What are the possible support types for space frame systems?

A
  • Column (point) supports
  • Inverted pyramid
  • Crosshead beams
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7
Q

Tensegrity

A

a stable three-dimensional space frame assembly of cables and struts where the cables are continuous but the struts are discontinuous and do not touch one another.

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8
Q

What does the term stayed apply to? (vertical hanger topic)

A

Tension hangers are not always vertical but often are inclined for either pragmatic or conceptual design reasons.

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9
Q

What was the worst structural disaster in the United States?

A

The Hyatt Regency, Kansas City, Missouri

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10
Q

Beam Definition

A

Linear structural member with loading applied perpendicular to its long axis: such a load is a bending load

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11
Q

Bending

A

The tendency of a member to bow as a result of loads applied perpendicular to its longest axis

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12
Q

What does bending cause?

A

One face of the member to stretch (tension) and the opposite face to shorten (compression)

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13
Q

What is the most common example of a structural member bending?

A

A beam

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14
Q

What stresses are also present when tension and compression stresses are occurring in parallel? (Beam)

A

shearing stresses

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15
Q

Difference between a tie and a hanger?

A

Hanger deals with gravity vs. a tie just locks elements to resist forces

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16
Q

In what form did beams originate?

A

Horizontal stone resting on two vertical columns

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17
Q

Bending stress

A

Combination of compressive and tensile
stresses developed at a cross section of the beam

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18
Q

Where are compressive and tensile stresses located on a simple span beam?

A

compressive in the top portion of the beam and tensile stresses are in the bottom portion of the beam.

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19
Q

How is beam efficiency increased?

A

by making the section deep with most of the material at the extremities – farther from the neutral axis – where the maximum bending stresses occur

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20
Q

Why is beam depth important to consider?

A

for reducing bending stresses and limiting vertical deflection

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21
Q

What do wooden beams support?

A

structural planking or decking.

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22
Q

What do steel beams support?

A

steel decking or precast concrete planks.

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23
Q

Horizontal spans may be traversed by…?

A

nearly homogeneous slabs of reinforced
concrete or hierarchical layers of steel or
wood girders, beams, and joists
supporting a plane of structural sheathing
or decking.

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24
Q

One-way slabs

A

supported continuously by 2 parallel supports and resist bending primarily in one direction

25
Q

Two-way slabs

A

supported on all 4 sides and resist bending in both directions

26
Q

Flat plates

A

slabs which are supported only at points by columns

27
Q

What is the most efficient shape for structural bays in one-way systems?

A

Rectangular

28
Q

Which way do one-way systems span in either square or rectangular grids?

A

Either direction

29
Q

Out of wood, steel, and concrete which material is compatible with two-way systems? (They all work with one-way)

A

Concrete

30
Q

One-way concrete slabs are….

A

uniformly thick and structurally reinforced to span in one direction between supports.

31
Q

What direction is the slab span in one-way systems?

A

usually in the short direction of rectangular bays.

32
Q

What are rigid, relatively slender structural members designed primarily to support axial compressive loads applied to the ends of the members?

A

Columns

33
Q

What structural member is a vertical support which is free from all sides taking the load of the beam and transfers the load to the earth independently?

A

Column

34
Q

What are the three fundamental elements of a classical column?

A

base, shaft, and capital

35
Q

Columns are usually ____ to _____ times longer than their width.

A

4 to 5

36
Q

Column Buckling

A

The buckling load of a column depends on its length, cross-sectional area and shape, and the type of connections at the ends.

37
Q

Column buckling (length)

A

Short columns fail by crushing and long columns fail by buckling.

38
Q

Column buckling (cross-sectional area and shape)

A

If the cross-section is not equally wide in both directions, buckling will occur in the axis of the most slender dimension.

For the same amount of material, columns with most of the material positioned as far from the center of the cross section as possible have higher buckling loads

39
Q

Moment of Inertia

A

the measure of the distribution of material around
the center of an object. Lowest when all the material is concentrated at the center. Highest when the material is distributed furthest from the center.

40
Q

Buckling load is directly proportional to…

A

the moment of inertia.

41
Q

Bearing Wall

A

a compressive member that is continuous in one direction that distributes vertical loads which spread gradually to the
support.

42
Q

Bearing walls should be…

A

continuous from floor to floor and aligned vertically from the roof to the foundation.

43
Q

What are top and bottom truss members called?

A

top and bottom chords

43
Q

What tendency do bearing walls have since they carry vertical compression loads and are relatively slender compared to their height?

A

Buckling

43
Q

Curtain Walls

A

Curtain walls are exterior walls
supported wholly by the steel or
concrete structural frame of a building
and carrying no loads other than their
own weight and lateral loads.

43
Q

Diagrids

A

a structure of
intersecting members
that form a diagonal
grid, connected at
specially jointed nodes
to create an integral
network across a
building surface
capable of resisting
lateral forces as well as
gravity forces.

44
Q

Where are bearing walls best suited?

A

where the load is distributed relatively uniformly.

44
Q

Pilasters

A

thickened portions of a
bearing wall under concentrated loads
that increase the area and reduce the
compressive stress (like a column
integrated into the bearing wall)

45
Q

What are all members between the top and bottom members of a truss called?

A

Web members

45
Q

Truss

A

a triangulated assembly that distributes loads to supports
through a combination of pin-connected members arranged in triangles to that ideally all are in either pure compression or tension (no bending or shear) and all thrust forces are resolved internally.

45
Q

What effect do openings have on bearing walls?

A

produce local areas of high compressive stress on either side of the opening.

46
Q

Space Trusses

A

A one-way structure that can be
visualized as two planar trusses
meeting each other at the bottom
chord with the top two chords
being framed as a third truss – a
three-dimensional one-way truss.

47
Q

What is the difference between plane and space trusses?

A

Plane trusses have all members in a single plane.

Space trusses have members in a three-
dimensional configuration.

48
Q

What is the difference between plane and space trusses and space frames?

A

Both plane and space trusses span in one
direction only – distinguishing them from
space frames which span in two
directions

49
Q

How are trusses usually placed relative to eachother?

A

Parallel

50
Q

Trusses are lightweight what does this mean?

A

they are deeper than beams would be if used on
the same span

51
Q

What kind of members are hangers?

A

Tension

51
Q

Where are trusses usually used?

A

In roof construction

52
Q
A