Midterm Flashcards
Name some basic building materials.
steel, concrete, wood, stone, brick
What materials are good in compression?
most: concrete, steel, brick, stone
What materials are good in tension?
steel
Describe how ancient construction is similar to construction today?
used similar materials, engineered, surveyed, similar amounts of labor, had a schedule, selected a suitable site, etc.
Why NYC for high rises?
limited land, had electricity, had steam pumps, clean water, elevators safety devices invented
Why building codes?
to ensure public safety, protect from unsafe design, protect from unsafe conditions, use of appropriate materials
What’s a building permit?
a certification from the city that state you have met conditions of appropriate codes
Types of NYC permits
NB (New building), Alteration Type I, Alteration Type II, Alt type III, Public assembly
What are air rights?
unused FAR that can be purchased or sold
why do we have to perform tests?
prove material is of adequate quality, prove assemblies constructed correctly
Describe differential settlement and uniform settlement
differential settlement is when one portion of a building settles more than others (ex. leaning tower of pisa)
uniform settlement is when the whole building settles the same amount
What concerns are associated with uniform settlement?
door issues, utility line issues
what concerns are associated with differential settlement?
internal stresses, facade cracks, doors and windows in building might be unusable
Name two main building loads and describe them
dead load - self weight of materials and permanent loads
live load - temporary loads and forces…people movement, furniture, snow
what is hydrostatic pressure and how does it affect foundations?
hydrostatic pressure is the water pressure in soil that presses on foundation and basement walls. it can create uplift or bow basement walls. Can increase dead load to counteract this pressure.
Does foundation affect other structures?
yes, loads in foundation impact nearby structures
what is soil bearing capacity?
the capacity of a soil to resist a given load
what is a boring and what is it used for?
a core sample of soil taken to identify soil types, water location and extract soils for testing
What is a split-spoon?
the end of a boring rig that separates to actually extract the soil
Describe a blow count test and state what it indicates.
a given weight is dropped a set distance and the number of drops it takes to push a casing into the soil is counted. indicates soil bearing capacity.
what kind of soil tests are performed?
sieve analysis, shear, compressive strength, water content, permeability, porosity, etc.
what is the Viele Map?
Map developed by Col. Egbert Viele in 1874 showing location of underground springs and poor soil
list basic foundation types
spread footing, piles, mat foundation, soil mixing, caisson
what’s a spread footing and why is it used?
column that ends at a square or rectangular box at a depth underground. Used because it’s relatively cheap, close to bottom of building, and can have better QC
What’s a pile and why is it used?
a steel, wood or concrete pole that is driven into the ground. Resists loads through bearing and friction. needs a pile cap. Used to reach material that may be deep below surface.
why a pile cap?
spreads loads over piles
how are piles tested?
load test to 2x capacity and settlement monitored
common types of piles
timber, h-pile, pipe, concrete, hybrid
mini-piles or micropiles
small drilled piles. less vibration, easier to install, can be used in tight spaces
what’s a mat foundation and why is it used?
large concrete pad the is the entire building size. loads distributed evenly over mat. can be very thick. Is used where water table is high, seismic loads, many interior columns, or poor soil conditions
whats a caisson?
drilled pier in the soil. can be very large. Used if needed to reach very deep materials, can achieve greater bearing area. limited vibrations. top of pile can used to support column
what’s an auger piles?
pile that made by drilling with auger then filled with concrete while drill is removed. then reinforcement is dropped in
simple and fast operation, that can reach great depths, but less load capacity
what is underpinning and shoring?
method used to protect adjacent structures from failure when constructing a project
what’s a needle beam?
a beam that is thread through a building to provide support when under construction
what are soil nails?
rods driven into soil to hold back shoring
what is trench support?
steel protection dropped into trench to protect working from a cave-in
whats a slurry wall?
a continuous retaining wall trench dug with a clam shell digger then filled with slurry, steel and then tied back
What are soldier beams?
retaining wall made by driving beams into the ground and filling in the walls with lagging
what are secant piles?
Piles drilled or driven close together to form retaining wall
why is waterproofing necessary for foundations?
protects structure from water intrusion,
What are some common methods of dewatering?
pumps, well point tied to header, coffer dam, slurry wall, soil freezing
what is soil freezing?
method to freeze soil so that water does not penetrate excavation
Why are logistics in construction important?
Contractor will have limited work zone and staging area, so much though must be given to how a building will be constructed
What’s an external climbing crane?
A crane that is attached to the outside of a building
What’s and internal climbing crane?
a crane that sits inside the building footprint. must have an opening for this crane
what should be considered when selecting a crane?
price, space, design of foundation, location, type of fuel
Describe the process of erecting a crane
a foundation is built, then crane pieces are assembled by a portable crane. to increase height, sections are “jumped”
what is a construction elevator called?
hoist
what are stand-pipes and where are they typically located?
a stand-pipe is a water hookup for firs and typically located close to hoist
List some impacts of a poor safety record
can get sued, workers comp and insurance can go up
name parts of steel beam
web and flange
what does the “230” is 12WF230 mean?
the beam is 230 lbs/ft
list some common steel shapes
beam, T, angle, channel
describe a long span joist
a small truss made up of smaller steel members
why use a truss?
truss can carry higher loads, but has great depth
what’s a tag line (for steel)
a rope used to help with orientation of the members
List the four steel erection gangs and their responsibilities.
- Raising Gang - sets the initial steel
- Bolting gang - temporarily connects steel… uses “spud” wrenches
- plumbing gang - makes sure steel is aligned and plumb
- finishing gang - bolts and tightens steel
what’s a turnbuckle and how is it used?
a device that tightens steel cables. used for plumbing
what is a steel baseplate?
a steel plate at the bottom of a column to distribute axial load bearing on concrete below
what’s a rivet and describe process
a permanent fastener that involves the deformation of a heated head to secure members
what is used to connect two pieces of continuous steel
a splice
what’s a cope?
material removed from steel to allow members to fit together
what are two main weld types?
fillet and groove
what are some common field tests for welding?
dye penetration, x-ray, ultrasound
what’s a camber?
a bend put into steel so that it will be level when loaded
what’s a shear stud?
a stud used to connect steel and concrete to create a composite member
is steel good under fire?
not really
list steel fireproofing methods
spray on monocoat
intumescent paint - paint that expands to protect steel when heated
drywall
why are columns installed in two story lengths
less fabrication, less connections, easier to plumb, larger columns would be more difficult
what is concrete composed of?
cement, sand, water, aggregate
what is well graded soil?
good range of soil sized and voids are filled
what is poorly graded soil?
soil mostly one size and has voids
what is gap graded soil?
soil sizes are large and small with none in the middle range
list some common concrete admixtures
air entraining - increases workability and helps with freeze-thaw
vibrating - self vibrates the concrete
corrosion inhibitor - helps reduce corrosion on reinforcing steel
accelerators - speeds curing time
retarders - slows curing times
pigment - adds color
how does temperature effect concrete curing?
cold temperatures slow curing and and stop it if cold enough. Loses strength with drop in temps
hot temps could cause flash setting and develop cracks
list the steps i a concrete pour cycle
- install shoring
- check elevation of formwork
- place formwork
- place chairs and reinforcement
- concrete ready to be placed
- start pour
- constantly check temps
- testing
- vibrate concrete to consolidate
- finish concrete
- cure
What’s a tie bar (for concrete)?
a bar used to hold formwork together
what is shoring?
supports used to hold up concrete deck that is under construction
what is slip forming and what is it typically used for in buildings?
slip forming is a continuous concrete pour in which the form moves as concrete cures. only used for core
what’s a tremie?
a funnel that allows concrete to be placed deeper in formwork so aggregate doesn’t separate from concrete “matrix”
list concrete placement methods
buggy, pumping, bucket and crane,
why does concrete need to be finished?
to make it smooth, increase density, and keep aggregate below surface
how is concrete finished?
by using floats and trowels
why is rebar used?
because concrete is bad in tension
what do the bar numbers indicate
diameter of the bar in eights of inches (ex. #4 bar is 4/8 in diameter)
what is a chair and why is it used?
small steel wire that lifts rebar off ground. used to create clear cover for rebar
what is welded wire mesh?
steel mesh used in smaller concrete pours for thermal stresses and cracking
what is used in concrete to resist shear loads?
stirrups
list types of concrete slabs
one-way - bends only in one direction
two-way - bends in two directions
flat plate - supported by columns
flat plate waffle
describe prestressed concrete
concrete is poured around strands in compression. once cured, strands are cut and put a compressive force on concrete
list advantages of prestressed
made in a lab, can be used for longer spans, can use less material
list some concrete tests
cylinders (not a test, but on slides) slump air content temperature weight compressive strength travel time
what can happen to concrete if too much air?
concrete can “honeycomb”
can reduce strength
what’s the max concrete travel time?
90 mins
what’s used to protect sewer system when washing out?
bales of hay
whats the primary objective during concrete curing?
to keep water in the concrete for as long as possible
what are some methods to increase water retention during concrete curing?
wetting down, using a curing compound, wet straw, wet burlap, plastic sheets
where was largest concrete pour performed?
Wilshire grand hotel, had to control heat
list some advantages of concrete
materials are readily available, fireproof, good blast protection, noise reduction, can create any shape
list some disadvantages of concrete
heavy dead load, can crack, labor intensive, greater testing requirements, requires steel, impacted by weather, needs time to cure
name some disadvantages of steel
requires fireproofing, needs components to hide structure
what’s a vapor barrier and why is it used?
barrier below roof that stops water vapor from getting into insulation and reduces vapor pressure. Used where condensation occurs below (cooking, mechanical room)
what considerations do you need to take into account when choosing a roof type?
must work with weather conditions, roof must be designed for loads, roof must meet factory standards for uplift
Name the 4 low slope roof types
built-up, single-ply, sprayed polyurethane foam, fluid applied
describe single ply roof
a single sheet of elastomer rolled onto roof
list some advantages of single ply
can be applied over existing roof, easy to handle, material is warranty backed
list some disadvantages of single ply
sealing of joints is key to success, no backup if punctured, requires ballast, if mechanically fastened stress may occur
describe built up roof
roof membrane built up from may different layers of material and several plys of asphalt soaked felt.
list some advantages of built-up roof
used successfully for many years, inexpensive, had many layers of protection
list some disadvantages of built-up
labor intensive, quality control issues, uv rays impact material, potential fire hazard, ponding can cause damage to plys
list advantages of spray on roof
can be applied over existing roof, good insulator, easy to flash, very light
list disadvantages of spray on roof
QC of material is critical, difficult to slope, problems with overspray, surface is rough
describe fluid applied roof
“painted on”
what’s an inverted roof?
insulation is above membrane
advantages of green roofs
reduces rain water, adds mass to the roof to reduce heat/cold transfer, increases life of membrane
disadvantage of green roof
adds weight to roof, difficult to repair, increased cost for vegetation
list common pitched roof types
terra-cotta, asphalt, metla
what is roof ballast?
stones on roof to hold membrane in place
what are some problems with roof ballast?
can puncture membrane, can blow off of roof
what’s an alternative to stone ballast?
ballast pavers
why is roof drainage required?
so water doesn’t pool, water can freeze
how to drain from roof?
sloped structure, scuppers, sloped insulation, scuppers, drains
what is flashing?
a cover at seams or penetrations to prevent water intrusion
list some things to look for in a roof inspection
no ponding, proper slope, flashing, no openings, no vegetation, no allegating, no “fish mouths”, no wet insulation, no overloaded areas
what is allegating and what does it indicate?
the roof membrane looks scaly, indicates membrane is drying out
what’s a cant strip?
an 45 degree angle at the comers so water doesn’t pool and less stress on membrane
what must an exterior wall be designed for?
wind loads, the dead load of it’s own material, joints, anchorage
what is local law 11/38?
facade must be inspected every 5 years
what is aluminum frame for curtain wall called?
a mullion
what is a setting block?
a rubber piece to distributive weight of glass in mullion
what’s a spandrel panel of glass?
glass that covers the floors, not in occupied space
what is a vision panel of glass?
glass over the occupied floor, what people actually look out of
list some types of glass
tempered - very strong glass, breaks into granules
laminated - glass sand sandwiches a plastic sheet
tinted - reduces the amount of transmitted light
insulated - double and triple pane
annealed - standard glass
what are two common curtain wall systems?
stick and modular;
stick - horizontal and veritical mullions with glass installed in the field
modular - full pre-assembled units installed in sections
how is a curtain wall supported?
with anchors attached to building floors
why are thermal breaks installed in mullions?
to reduce thermal bridging
list some items that are tested on curtain walls
air infiltration, water intrusion, expansion and contraction
structural integrity, impact testing, constructability
list types of window cleaning rigs?
boom, carriage, portable davit, bosun chair
What does BTU stand for and what is it?
British Thermal Unit; a measurement used to describe heat gain/loss
What is the historical meaning of BTU?
amount of heat required to raise one pound of water 1 deg F
