structures test 2

A linear structural member with loading applied perpendicular to its long axis

A linear structural member with loading applied perpendicular to its long axis

bending load

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

Bending

Bending causes one face of the member to

Stretch (tension)

Bending causes the opposite face of the member to

Shorten ( compression)

Because the tension and compression stresses are occurring in parallel,

shearing stresses are also present

most common example of a structural member in bending

Beam

Cantilever

simply supported

overhanging

Continuous

fixed ended

Cantilever, Simply Supported

what is an important consideration for reducing bending stresses and limiting vertical deflection

beam depth (height)

Where does the maximum bending stress occur

farther from the neutral axis

Wood beams support

structural planking or decking

Steel beams support

steel decking or precast Concrete planks

One way systems are more effective when structural bays are

rectangular

When the structural bays are rectangular

the ratio of the long to the short is greater than 1:5:1.

One way systems can span

in their directions of square or rectangular bays

what is appropriate for both one way and two way spanning systems

Concrete

What can lend themselves to one way systems

wood and steel spanning elements

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

One way concrete slabs

The direction of the slab in a one wat concrete slab is usually in the

Short direction of rectangular bays

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

One way slabs

Supported on all 4 sides and resist bending in both directions

Two way slabs

Slabs which are supported only at points by columns

Flat Plates

columns

Rigid, relatively slender structural members designed primarily to support axial compressive loads applied to the ends of the members

A vertical support column

is free from all the sides taking the load of the beam and transfers the load to the earth independently

Classical column fundamental elements are

Base, Shaft, and capital

a column is generally

at least 4 or 5 times as high as its diameter or width

The buckling load of a column depends on

its length, cross-sectional area and shape and the type of connections at the ends

A short column fails by

Crushing

A long column fails by

Buckling

An intermediate column fails by

a combination of Crushing and Buckling

Once a column begins to buckle

it fails suddenly and without warning

The Buckling load varies inversely as

the square of the length of the column

Doubling the length will reduce the load

25%

Halving the length will increase the buckling load

400%

If the cross section is not equally wide in both directions

Buckling will occur in the axis of the most slender dimension

Columns with most of the material positioned as far from the center of the cross-section as possible

have higher buckling loads

Moment of inertia

The measure of the distribution of material around the center of an object

Buckling load is

Proportional to the moments of inertia

Doric order

Ionic order

Corinthian order

The tie

tention

The hanger

Tension member

Significant weight or load is being carried at the bottom

a Vertical hanger

Remarkably thin, long vertical element is connected to the load

a vertical hanger

a support structure of one type is located at the top end to which the hanger is anchored

A vertical hanger

Tension Hangers

are not always vertical but often inclined

What term is applied to inclined structures for their pragmatic or conceptual designs

Stayed

a space frame

a 3 dimension trussed system spanning in two directions where members are in tension or compression only

Space frames consist of

identical repetitive modules with parallel upper and lower layers.

Half- octahedron and the tetrahedron

widely used polyhedral modules for building space frames

Tensegrity

a stable 3-dimensional space assembly of cables and struts

In a tensegrity,

cables are continuous but the struts are discontinuous and do not touch one another

tensegrity, is islands of

compression inside an ocean of tension