Materials and Thecnology Flashcards
(15 cards)
Site Excavation Hydraulic or pneumatic shoring sheet piling soldier piling secant piles cofferdams
Types of shoring:
Hydraulic or pneumatic shoring for deep narrow trenches to pour footings or utility line. Benefit of this method is that workers do not have to enter the trench to install the shoring.
Sheet piling for deep surface excavations. Is vertical lining of excavated area with steel sheets, by driving tension rods into grouted hole or into concrete block call deadman.
Soldier piling requires driving of wide flange shapes into the ground then steel sheets or wood boards called larger boards are slid between the piles.
Secant piles are used on sites with large boulders that can apply strong forces of shoring. This is more expensive but can be covered with slurry and incorporate in permanent design so there is not removal cost.
Cofferdam are for underwater excavations. They are driven into the water bed to enclosed the intend area. This are also used for deep foundation system such as piles or caissons as they typically extend far below the water table. Cellular cofferdams filled with concrete are used where a permanent water barrier is needed. Water within the excavation is then pumped out with a submersible pump.
Deep excavation in a high water table needs dewatering. For surface excavation wellpoints are drill along the excavation connected through a line that connects to a pump. The water around the excavated area is pumped out.
Shoring on existing structures
Underpinning
Cribbing
Shoring for existing structures
Underpinning is when shoring is needed for an existing structure when a foundation or structural wall must be removed.
Cribbing is an underpinned method that required lifting of the existing structure in place. The structure is lifted using hydraulic jacks. Then steel beams are place on top of box cribbing piles. Cribbing is used for a small raised structure.
Underpinning for larger structures or built on grade requires excavation to stabilize the building, and we used needled beams that are driven through existing foundation to support the building.
Site Drainage
Runoff
Runoff coefficient
Runoff is Additional storm water that does not seep in to the ground. The site design must also create positive drainage to avoid flooding, erosion and standing water.
Runoff coefficient is the fraction of the water not absorbed
Sheet Flow
Minimum slope of underground systems
function of drain inlet
Definition of catch basin
Sheet flow is water that drains across a slopping surface.
Underground systems use piping with a minimum slope of .3%.
A drain inlet simply allows stormwater to run directly into the storm sewer.
A catch basin has a sump built into it so that debris will settle instead of flowing down the sewer.
What should happen is municipal allowance of run-off is exceeded?
run off must be retained on site permanently or temporarily. It may need to be treated if pollutants are likely
Management practices (BMPs) for storm water infiltration into soil
Reduction of run-off volumes through increase infiltration or storage.
1- curb and gutter elimination is encouraged to deter fast flowing sheet water that can overflow storm sewer during peak rainstorms
2. green parking- permeable pavement and sediment control
3. riparian buffers- grassed setback from wetland, shoreline or stream
4. grassed swales- for low slope on small sites
5. soil amendments are addition of soil conditioners and fertilizers to promete percolation
6.permeable pavement infiltration contains a stone reservoir (gravel) around an underdrain (french drain) below to slow infiltration
7.Permeable unit pavers: are design to interlock above natural soil allow grass to grow between paver voids.
8. stormwater planters increase permeable surface to reduce run off
9. tree box filters can reduce run off for retrofit projects or in urban areas
10. rain barrels and cisterns storage untreated soft water. harvested rainwater.
11. recharge basin is a storm water collection pond above and underground water body or aquifer that slowly infitrates into the quifer to recharge groundwater
12. detention ponds are temporary storage of run off that permits natural infiltration. water should not be confined with gravel, clay or silt.
13. Retention ponds are a permanent storage of rainwater on site. To prevent absorption into the soil, ponds are line with plastic sheathing
Ways to avoid erosion
1-retaining walls. locate geotextile silt fence on the leward side of retaining wall
2-compost berm
3- gabion baskets
Moisture mitigation
Air and Vapor barrier
Damp proofing
Water proofing
1-On the outside of the building. (warm side)
2-consists of the materials and methods that prevent moisture from penetrating a building at or below grade. bentonite, bituminous coating, asphalt coating
3-consists of the materials methods to prevent water under hydro static pressure. membrane waterproofing
The 2 defining features of electrical lighting
- color rendition! index CRI: is measured from 1-100. It measures light vibrancy in comparison to sunlight. and color temperature
- Color temperature: is measured in units called kelvin (K). higher kelvin lamops results in blue toned color rendition or cool colors.
4 lamp families
tungsten, gaseous, diode, induction
tungsten: Incandescents are warm toned lamps that contain an iert gas, while halogens contain iodine. This type of lamp is suitable for accent or display lighting as they have a high CRI. ILUMINATION IS CAUSED BY THE TUNGSTEN FILAMENT NOT THE GAS that seals it.
gaseous lamps: pass current through a gas contained in the lamp. it requires evaporation of a small amount of mercury. There is a part of the lamp called a ballast that regulated the current for mercury evaporation and illumination. Suitable for general indoor use such as residential and office. Extremely low or high outdoor temperature decreases the light efficiency of fluorescent lamp.
Induction lamps are similar to fluiorescent lamps but use radio waves instead of electricity to eliminate the gas inside the bulb. high cost. suitable for areas that are hard to reach. last 20 years.
Light emitting diode (LED) is a low energy, high CRI lamps that have been long used for exit signage and indicator light in electronics. It generates lights in a single direction therefore it does not disturb other lights
HID High intensity discharge
these are general hot lamps and should be mounted high.
Mercury lamps are HID Lamps with a blue tint.
Metal halide are the most versatile indoor and outdoor lamp, They are argon filled lamps that emit a high CRI. As metal halide are at risk for random bursting, they require a cover. Suitable for outdoor stadiums, landscape, and facade lighting.
High pressure Sodium Lamps (HPS)
These are HID (high intensity discharge) lamps with a warm yellowish tone. suitable for parking lots, storage, industrial, farmhouses, and general outdoor lighting.
Low pressure sodium (LPS)
have the lowest CRI of any lamp. They emit a yellow toned light and are best suitable for public roads.
light trespass
It is critical for the site lighting to stay within the site boundary. light that trespasses to adjacent areas can be disturbing. directional devices such as SHIELDS, HOODS, BAFFELS, LOUVERS AND REFLECTORS are used to mitigate light trespass. Light should be directed down with a maximum of 45 degree throw. To preserve the night sky for habitat. HPS, or LPD should be use.
Visible transmittance
Is the percentage of sunlight that will pass through glazing. It is based on the glazing thickness, number of panes and clarity. It is express on a value between 0-1
