5 - PDD Flashcards
what are 4 material characteristics that should be considered when selecting exterior materials for a building?
- properly used
- withstand elements
- how often does it require maintenance?
- how well does it perform for its intended use & longevity?
how should the performance of materials be considered during the design phase?
- tested to assure they will perform as expected
- life span, withstand normal wear & tear
how does building orientation affect natural daylighting?
- north = no direct sunlight
- south = fair amount year round
describe the treatments for a north facing window vs. east facing
- north: no direct light but an even glow from reflected light all day, in hot places they have almost no heat gain, in cold climates almost always cold and grey
- east: receive sunlight in morning, start warming building at beginning of day
describe the treatments for a south facing window vs. west facing
south: receive sunlight nearly all day; in hot climates use overhangs to block summer sun (a 2’ overhang will shade summer, but allow winter in)
west: receive hot afternoon sun until sunset, much lower in sky so overhangs dont help, use louvers to control
what is a free body diagram?
to analyze forces on and within structures, use this technique from physics (FBD)
representation of a body and all forces & moments acting on it - does not include internal forces
what structural connection can resist either x or y forces, but not moment?
pinned connections
this type of structural connection only resists forces in the y direction
roller connections
within any structural member in bending, _____ is quantified as the maximum translation measured perpendicular to its central axis
deflection: vertical distance that the beam sags at midspan
usually expressed as a fraction of the span (often noted as greek letter delta)
the formula for deflection of a beam with a uniformly distributed load is:
delta = 5 wl4 / 384 EI
the fibers within a beam develop an internal moment to resist the moment caused by deflection. this resisting moment is called:
bending moment
the centroid of an area is conceptually defined as:
the center of gravity of a mass
for simple geometric shapes, this is easy… for many common asymmetrical shapes, it is calculated
a factor relating the shape of a structural section and the distribution of its material relative to a chosen axis is called:
a section’s moment of inertia, usually denoted “I”
the units of moment intertia are in4 or inches to the fourth power
ratio of a sections moment of inertia and the distance between the neutral surface & outermost edge of the section, “c” is referred to as:
the section modulus
S = I / c
the 2 reasons that column buckling occurs are:
- if an applied load is eccentric, or if it doesn’t occur exactly at a column’s centroid, it will impart some degree of moment, causing bending
- no material is truly uniform in its internal composition; any very slight variation of the material will tend to allow buckling
finding this value quantifies a cross section’s ability to resist buckling under an axial compressive load by relating its moment of inertia & area
radius of gyration = convenient parameter, providing measure of the resistance of a cross section to lateral buckling
a load imposed on a structural member at some point other than the centroid of the section is called:
eccentric load
bending stress is a function of the section modulus and the:
bending moment
define slenderness ratio
ratio of a wall or columns unsupported height/length to its thickness (measures ability to resist buckling)
vertical steel reinforcing within reinforced concrete columns essentially are very slender _____ when compressive stress is applied
columns
a special kind of made up beam that uses members efficiently by placing them in pure compression or tension, when loaded properly, to carry loads over a span is called a:
truss
the two methods for manually analyzing trusses are:
- method of joints
- method of sections
in this type of truss analysis, a cut is made passing through no more than 3 members, and the 3 equations of equilibrium are applied
method of sections
forces acting toward a joint indicate a truss member is in:
tension