Civil and Environmental Engineering Answers

An employee is selected from a staff of 10 to supervise a certain project by selecting a tag at random from a box containing 10 tags numbered from 1 to 10. (a) Find the formula for the probability distributions of X representing the number on the tag that is drawn. (b) What is the probability that the number drawn is less than 4? (c) Find the mean and variance of the random variable X.

A 300mm square column is reinforced with 3Φ16 bars at each of the two critical faces. If C25 concrete and steel with fyk=300MPa is used, compute the ultimate axial compressive force the section can safely resist.

Given the definitions of Ethics, write down 5 reasons (in sentence form) as to why it is important. Specifically, why does ETHICS030 should be a part of the learning curriculum?

Brigham Tea, Inc., is a processor of low acid tea. The company is contemplating purchasing equipment for an additional processing line. The additional processing line would increase revenues by $90,000 per year. Incremental cash operating expense would be $40,000 per year. The equipment would cost $180,000 and have a nine-year life. No salvage value is projected.

find the centroid of the area bounded by the curves y^2=x and x=4

Design the concrete mix according to the following conditions:

Design Environment

Building frame

Required design strength = 27.6 MPa

Minimum dimension = 150 mm

Minimum space between rebar = 40 mm

Minimum cover over rebar = 40 mm

Maximum slump is required

Statistical data indicate a standard deviation of compressive strength of 2.1 MPa is

expected (more than 30 samples).

Only air entrainer is allowed.

Available Materials

Air entrainer: Manufacture specification 6.3 ml/1% air/100 kg cement. (Use maximum

or +2% air content)

Coarse aggregate: 19 mm nominal maximum size, river gravel (rounded)

Bulk oven-dry specific gravity = 2.55, Absorption = 0.3%

Oven-dry rodded density = 1761 kg/m³

Moisture content = 2%

Fine aggregate: Natural Sand

Bulk oven-dry specific gravity = 2.6

The design of a concrete mix requires 1173 kg/m3

of gravel in dry condition, 582 kg/m³ of sand in dry condition, and 157 kg/m³of free water. The gravel available at the job site has a moisture content of 0.8% and absorption of 1.5%, and the available sand has a moisture content of 1.1% and absorption of 1.3%. What are the masses of gravel, sand, and water per cubic meter that should be used at the job site?

What is your recommendation for the maximum size of coarse aggregate for the following situation? A continuously reinforced concrete pavement cross section contains a layer of No.6 reinforcing bars at 6-inch centers, such that the steel is just above mid-depth of a 10-inch￾thick slab. Cover over the top of the steel is therefore about 4 inches.

A project specifies a concrete strength of at least 3000 psi. Materials engineers will design

the mix for a strength higher than that. Calculate the required average compressive strength of

the mix design if the standard deviation is s = 350 psi. Estimate the modulus of elasticity of the

concrete at the required average compressive strength.

A project specifies a concrete strength of at least 3000 psi. Materials engineers will design

the mix for a strength higher than that. Calculate the required average compressive strength of

the mix design if the standard deviation is s = 350 psi. Estimate the modulus of elasticity of the

concrete at the required average compressive strength.