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Civil Engineering
Civil Engineering is a profession of designing and executing structural works that serve the general public, like houses, buildings, roads, etc. A Civil Engineer is an engineer trained in the design and construction of public works, such as bridges or dams, and other large facilities.
4,921 Questions
What is an advantage and disasvantage of a suspension bridge?
PRO: they can be built over waterways, and can be built high, letting taller ships to pass under
PRO: Temporary supports in the middle to keep the bridge from falling aren't needed to keep the bridge from collapsing
CON: They are very flexible and can bend under heavy loads if they are in one spot
CON: They use expensive foundation work with all the load going on if in soft ground
How do you calculate section modulus of a T section?
This is a technique used by civil and mechanical engineers to calculate the cross section of a geometric figure. It is used to determine the Yield Moment also called My.
What is plank and beam construction?
Plank and beam is typically referred to as post and beam. This type of construction is used a large percentage of the time for new home construction. It is used in colder climates more than warmer climates because you have the ability to insulate under the floor of the house. In warmer climates slab floor construction is used more than it would be used in colder climates. There is another type of construction that is used but not as often. It is called the joist system. This is the way Post and Beam construction works. A vertical member (post) is set on concrete pads, about 8 feet apart. The horizontal member(beam) is set on the posts. The spacing between the beams are typically 4 feet apart. The end of the beams are placed in beam pockets that have been designed into the foundation. Then 2"x6" or 2"x8" tongue and grove planks are placed perpendicular on the beams to create the floor. In slab construction you pour a concrete floor between the footing and foundation. A joist system uses 2x material to span between two points and tie into a ledger board using metal hangers. This system is used for decks more often and the 2nd and 3rd floors of homes.
Is timber a ductile or brittle?
Timber is very strong and can be used for structural building. It is very easy to use and it is very useful.
What are gasoline engines and diesel engines?
The Diesel cycle engine was named after the German engineer who invented it, Rudolf Diesel. A Diesel engine uses two principles: air gets hot when you compress it, and fuel will ignite if it gets hot enough. The engine compresses air introduced into the cylinder to a very high pressure. When fuel is injected it immediately ignites.
Yes, shale is considered a common rock. Also, out of all the sedimentary rocks, it is the most common one.
Methods of underwater concreting?
This is a method on how to place concrete underwater, this method place a big role in offshore concreting, since cement looses its strength and fade away under water, Tremie method is to be used. Tremie Concrete is done by using a formwork/pipe which will have one end of the formwork/pipe above water and other bottom end immersed under the water and with the help of gravity.
A tremie is a watertight pipe, generally 250mm in diameter, having a funnel shape hopper at its upper end and a loose plug at the bottom or discharge end. The valve at the discharge end is used to de-water the tremie and control the distribution of the concrete. The tremie is supported on a working platform above water level, and to facilitate the placing it is built up in 1 to 3.5m section.
During the concreting, air and water must be exclude from the tremie by keeping the pipe full of concrete all the time; and for this reason the capacity of the hopper should be at least equal to that of the tremie pipe. In charging the tremie a plug formed of paper is first inserted into the pipe as the hopper is filled the pressure of fresh concrete forces the plug down the pipe, and the water in the tremie I displaced by concrete.
For concreting, the tremie pipe is lowered into position and the discharge end is kept as deeply submerged beneath the surface of freshly placed concrete as the placed concrete as the head of concrete in tremie permits. As concreting proceeds the pipe is raised slightly and the concrete flows outwards. Care should be taken to maintain continuity of concreting without breaking the seal provided by the concrete cover over the discharge end. Should this seal is broken, the tremie should be lift and plugged before concreting is recommended. The tremie should never be moved laterally though freshly placed concrete. It should be lifted vertically above the surface of concrete and shifted to its new position.
When large quantities of concrete are to be placed continuously, it is preferable to place concrete simultaneously and uniformly through a battery of tremies, rather than shift a single tremies from point to point. It has been recommended that the spacing of tremies be between 3.5 and 5m and that the end tremies should be about 2.5m from the formwork. The risk of segregation and non-uniform stiffening can be minimized by maintaining the surface of concrete in the forms as level as possible and by providing a continuous and rapid flow of concrete.
How is the Underwater Concrete Mixes?
For Structural concrete following must be considered
- Coarse Aggregate: Gravel of 3/4" (20mm) max. size. Use 50-55 % of the total aggregate by weight.
- Sand, 45-50% of the total aggregate by weight.
- Cement: Type II ASTM (moderate heat of hydration), 600 lbs/yd3
- Pozzolans: ASTM 616 Type N or F, 100 lbs/ yd3
- Water/Cement Ratio: 0.42 (0.45 Maximum).
- Æ’Water-Reducing Admixture (preferably it is also plasticizer): Do not use superplasticizers.
- Æ’Air-Entrainment Admixtures: To give 6% total air.
- Æ’Retarding Admixture: To increase setting time to 4-24 hours, as required.
- ƒSlump: 6 1/2" ± 1"
- Æ’This mix will develop compressive strength in the range of 5,600 - 7,000 psi at 28 days.
Who was the architect of the Mackinac bridge?
The Mackinac Bridge is a suspension bridge spanning the Straits of Mackinac, and connecting the Upper and Lower peninsulas of Michigan.
Envisioned since the 1880s, the bridge was completed in 1957, only after many decades of struggle to begin construction. Designed by engineer David B. Steinman, the bridge connects the city of St. Ignace on the north end with the village of Mackinaw City on the south end.
It is the third longest in total suspension in the world and the longest suspension bridge between land masses in the Western Hemisphere. The Mackinac Bridge carries Interstate 75 across the straits.
Which metal is used to mend railway tracks?
The key element in railway lines depending on the railway line is, occasionally copper, magnesium and stainless steel.
How does hydro energy make energy?
Hydroelectric energy uses the potential energy of a mass of water in a high reservoir, that is released by running the water down pipes so that it gathers speed and eventually hits turbine blades to rotate a shaft that turns an electric generator.
The potential energy of the water comes from the Sun, which evaporated the water from the sea or other place and deposited it at a high level via rain on the upper part of the mountain.
What is the difference between compressive strength and target strength?
Compressive strength of concrete is defined as the concrete cube of 150 mm x 150 mm x 150 mm with specified proportion with 28 days curing.
Target mean strength - In order that not more than the specified proportion of test results are likely to fall below the characteristic strength, the concrete mix has to be designed for a somewhat higher target average compressive strength (fck).
__
fck = fck + t * s
where ___
fck is target average compressive strength at 28 days,
fck is a characteristic compressive strength at 28 days and
s standard deviation
t a statistic, depending upon the accepted proportion of low results and the number of tests.
What is the meaning of 415 in fe 415?
The abbreviation Fe stands for Ferrous material ie ironfrom which the reinforcement steel bars are manufactured.
The reinforcement steel bars used in RCC (Reinforced Cement Concrete) are designated as Fe415 or Fe500 depending on their Yield Strength. (The numbers 415 and 500 tell about this Yield Strength in N/mm2 the bars are designed and manufactured to have.)
Fe415 indicates that the Yield Strength (tensile strength) of steel is 415 N/mm2.
What is the largest man made harbor in the world?
Two ports vie for the title of the largest port in the world depending on how they are evaluated. If the measuring standard is based on weight or "tonnage," the largest port in the world is Shanghai, China. Where as, if the measuring standard is the TEU, the shipping "standard unit of measure, then the largest port in the world is Singapore, Singapore.
How do you get a distributed load?
By adding more supports. Best illustrated by examples.
* A tire swing with only one rope looping around a tree branch is an example. Tying a second rope to the tree branch distributes the point load to 2 points (2 loops).
* a loaded wheelbarrow with one front wheel -- if used repeatedly across a path in the lawn -- will cause an ugly bare strip of mud at the end of the day. One can put broad wood planks end-to-end on the path. When the wheel goes over the plank, the load is redistributed from a single point contact to the whole plank, ideally. Instead of say 100 lbs per square inch, the load becomes 10 lbs per square inch (no plank or lawn is perfectly flat), saving the lawn for another day.
* a similar example would be walking on mud. One can put end-to-end planks on the trail or spread a thick layer of pebbles on the mud. Instead of one's shoes sinking deep into mud, walking on planks or rocks is much more comfortable and easy and clean too.
* snow skis -- the load is distributed from the ski boots to ten times the surface area so one can ski on snow rather than getting stuck in snow.
* heavy furniture with four legs will make deep troughs in the carpet with time. Place a piece of wood at the bottom of each leg reduces the pressure on the carpet so the depressions can be recovered.
* a 4-wheel truck can carry more load if it is turned into a 6-wheeler. Eighteen wheelers can be bigger and hold heavier load than a six-wheeler.
The same concept can be applied to supporting engineering structures that are heavy and may be unstable.
What is a soil test for building construction?
There are a large number of soil tests related to construction:
- Particle Size Distribution test - finds the relative proportions of differing grain sizes within a soil
- Atterberg Limit test - used to establish the plasticity class of the soil
- Compaction test - used to find the optimum moisture content to achieve a maximum density
- Consolidation / Oedometer testing - used to establish the settlement potential of a fine grained soil.
- Direct Shear test - used to measure the peak (and potentially residual) shear strengths of a soil. When tested at varying confining loads can be used to find the shear strength parameters Phi' and c'*
- Triaxial testing - used to find the elastic properties of the soil (Young's Modulus and Poisson's Ratio) along with the shear strength. These may be either drained or undrained tests.
- Constant and falling head permeability tests - used to establish the hydraulic conductivity / coefficient of permeability for coarse and fine grained soils respectively.
*Note in the UK c' is assumed to be zero for design purposes, in other countries small non zero c' may be used.
How much weight can a 6x6 steel i-beam support?
It depends on the type of beam, the material, whether it is a bridge span or cantilever, the allowable deflection and safety margin needed. We need a lot more data on the application.
What is the mass in kg of 1 square meter of 2 mm mild steel sheet?
The steel sheet in question has a volume of 1 x 1 x 0.002 m3. Mild steel has a density of 7800 kg/m3.[A]
As such the mass = 7800 x 0.002
Mass = 15.6 kg
[A] Cobb, F. (2009) Structural Engineer's Pocket Book, 2nd Edition. Amsterdam, Elsevier.
How many acres do you need for a 100000 sf building?
10,000 square feet equates to about 1/4 of an acre.
How long did it take to build the underwater portion of the golden gate bridge?
The original Sunshine Skyway Bridge was constructed in 1954, but destroyed in 1980. The new bridge took five years to build and construction took place from 1982-1987.
What are the advantages and the disadvantages of a beam bridge?
It is a disadvantage that the same reason Hay's bridge was created is the same reason it is not suitable for measurement of quality factor (Q<10) for Q<10. An advantage is that it is simple expression of the unknown inductor for high quality.
What is hardening of concrete?
Cement when mixed with sufficient quantity of water,the compounds present in cement reacts with water to form a cementitious crystalline structure that adheres to the sand and aggregates.This helps in binding the mass together and increases its strength till it becomes very hard.This is called hardening of cement.
What is the formula to find pressure loss in fire fighting pipe lines?
pips are generally cylindrical in structure of amount of heat loss through pipe is given by the formula Q= 2 pi k L(T1-T2)/ln(r2/r1) where k=conductivity of material of which pipe is made T1= temperature of inside layer pipe T2=temperature outside layer of pipe L= length of pipe r1= inner radius r2=outer radius ln=natural logrithem pi=22/7 the above condition applies for steady state flow,single layer over cylinder and neglecting conductivity convection to take conductivity convection into account term Q* must be added Q*=2 pi L{ r1 hi(Ti-T1)+r2 ho(T2-To)} hi=convective coefficient for inside layer ho=convective coefficient for outside layer Ti= temperature of inside space of pipe To=temperature of outside space of pipe for unsteady condition there is another formulaa
1. Excavation of the soil up to required depth.
2. Ramming the foundation bed.
3. Cutting the concrete over the reinforcement.
4. Laying the reinforcement over the the foundation bed.
5. Pouring the cement concrete over the reinforcement.
