Exam 3

Question 1

A hanging rope, cable, or chain needs supports at its ends that are_____.

Answer 1

fairly stiff

Question 2

What are cable structures shaped in accordance to?

Answer 2

They have no bending or stiffness so it’s shaped in accordance to the location and magnitude of the loads which it supports.

Question 3

When will a cable change its profile?

Answer 3

If the loads that are applied to it change location

Question 4

What quality of the cable has to be dealt with to ensure that the structure does not move excessively?

Answer 4

Lack of rigidity

Question 5

In which direction is a hanging cable structure fundamentally unstable?

Answer 5

Sideways direction

Question 6

What do hanging cable structures primarily work in?

Answer 6

Tension (that’s why they are so light)

Question 7

What do cable stayed structures consist of?

Answer 7

towers or masts from which cables extend to support horizontally spanning members. the supported structural surface must be sufficiently stiff to transfer or resist the lateral and torsional stresses induced by wind, unbalanced live loads, and the normal force created by the upwards pull of the stays

Question 8

What are the two primary cable configurations in cable stayed structures

Answer 8

radial or fan patterns and parallel or harp systems

Question 9

What is the difference between radial and parallel systems in cable stayed structures?

Answer 9

Radial systems attach the upper ends of the cable stays to a single point at the tip of the tower, parallel systems secure the upper ends of the cable stays to the mast at different heights

Question 10

Why is the radial system usually preferred over the parallel system in cable stayed structures?

Answer 10

Because the single point of attachment minimizes the bending moment in the tower. The cable stays are usually attached symmetrically to a single tower or mast with an equal number of stays on both sides

Question 11

Membrane Structures

Answer 11

Thin, flexible surfaces that carry loads primarily through the development of tensile stresses

Question 12

Net Structures

Answer 12

membrane structures that have a surface of closely spaced cables instead of a fabric material
three dimensional and double curved and pre-stressed

Question 13

Pneumatic structures

Answer 13

membrane structures that are placed in tension and stabilized by the pressure of compressed air

Question 14

What are air-inflated structures?

Answer 14

pneumatic structures supported by pressurized air within inflated building elements which are shaped to carry loads in a traditional manner while the enclosed volume of building air remains at normal atmospheric pressure.

Question 15

How is the tendency of double membrane structures bulging in the middle restrained?

Answer 15

By using a compression ring or by using internal ties or diaphragms

Question 16

DEFINITION OF A DOME

Answer 16

Domes are surfaces of revolution, usually generated by rotating an arc of a circle around
a vertical axis.

Question 17

• A spherical surface structure having a circular plan and constructed of a continuous rigid
  material or of short, linear elements.

Answer 17

DOME

Question 18

Meridional forces are always under full vertical loading

Answer 18

compressive

Question 19

A dome is similar to a rotated arch except that…

Answer 19

circumferential forces are developed which are
compressive near the crown and tensile in the
lower portion.

Question 20

Hoop forces, restraining the out-of-plane
movement of the meridional strips in the shell of
a dome, are

Answer 20

compressive in the upper zone and
tensile in the lower zone

Question 21

What encircles the base if a dome to contain the outward components of the meridional forces

Answer 21

tension ring

Question 22

Shell

Answer 22

thin, curved surface structure that transfers loads to supports by tension, compression, and shear only.

Question 23

Developable surfaces

Answer 23

are singly curved, they are straight in one direction curved in the other and can be formed by bending a flat sheet cones and cylinders (or barrels are developable

Question 24

anticlastic surfaces

Answer 24

doubly curved and have opposite curvature in each direction (saddle shapes including conoids, hyperbolic paraboloids, and hyperboloids) are anticlastic

Question 25

conoids

Answer 25

generated by sweeping one end of a straight line along a curved path and the other end along a straight line

Question 26

hyperbolic paraboloids

Answer 26

generated by sweeping a convex parabola along a concave parabola of the same curvature. the same surface can be generated by sweeping a straight line over a straight path at one end and another straight path

Question 27

Stresses in hypars relate to…

Answer 27

direction of curvature, compression stresses follow the convex curvature (arch) while tension stresses follow the concave curvature (suspension)

Question 28

Is an arch in compression or tension?

Answer 28

Arches are pure compression forms

Question 29

How can arches span large areas?

Answer 29

By resolving forces into compressive stresses and eliminating tensile stresses

Question 30

What is a thrust? (arch)

Answer 30

As forces are carried to the ground the arch will push outward at the base

Question 31

What happens to thrust as rise (height) decrease?

Answer 31

Rise decrease makes thrust increase.

Question 32

How are thrusts restrained?

Answer 32

Either with internal ties, or external bracing, such as abutments.

Question 33

An arch fails due to:

Answer 33

-crushing of the masonry
-sliding o voussoirs
-rotation of some joints about an edge
-uneven settlement of an abutment or pier

Question 34

How are arches classified?

Answer 34

Type of arch, geometry, materials of construction

Question 35

How are shells distinguished from traditional vaults?

Answer 35

By their ability to resist tension

Question 36

Free-form surfaces are____

Answer 36

those which are not mathematically derived.

Question 37

A dome is similar to a rotated arch except that…

Answer 37

circumferential forces are developed which are
compressive near the crown and tensile in the
lower portion.