10 MO21. A civil engineer is analyzing the compressive strength of concrete.Compressive strength is normally distributed with population varianceequal to 991(psi)^2. A random sample of 12 specimens has a meancompressive strength of 3317 psi. Construct a 95% two-sided confidenceinterval on mean compressive strength. The upper limit of the Cl of the Cl isBlank 1 in the blank provided up to 2 decimal places. Show all necessarysolutions in the submission for both upper and lower limit.Blank 1Add your answer

Sample Mean \bar XXˉ = 33173317 Population Standard Deviation (\sigma)(σ) =…

Engineering

Civil Engineering

0

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

6′′ * 12′′ concrete cylinders were made of the same batch and separated at random to six equal groups. The six groups of cylinders were submerged in water for different times before testing for compressive strength and the results are shown in Table . It is required to do the following:a. Determine the compressive strength at different curing times.b. Using an Excel sheet, plot the relationship between curing time and compressive strength. Label all axes and curves.c. Comment on the effect of curing time on the compressive strength.d. What is the approximate ratio between the compressive strengths at 7 days and 28 days?e. What is the approximate ratio between the compressive strengths at 28 days and 180 days?
The results of 15 compressive strength tests for a 20 Mpa requirement are detailed in the table below. Find the standard deviation and determine the overdesign required. (keep your answers and calculations to 1 decimal place; that is round to one decimal place) Test Strength (MPa) (x - x avg.)2 22.1 21.3 20.6 16.8 17.2 20.1 24.1 23.6 18.3 17.8 20.4 16.4 19.8 23.9 20.5 Average strength = ______ Mpa Standard Deviation = Overdesign = 20 Mpa + _____Mpa
Calculate the corresponding depth of uniform stress block in a reinforced concrete beam 50*10 deep reinforced with bars 20-mm in diameter enclosed with 10-mm-dia stirrups when the tensile steel strain is 0.008 and concrete compeession strain is 0.003. f’c = 20 MPa express your answer in 2 decimal places only in mm
150 mm * 300 mm concrete cylinders were made of the same batch and sepa- rated at random to six equal groups. The six groups of cylinders were sub- merged in water for different times before testing for compressive strength and the results are shown in Table P7.39. It is required to do the following: a. Determine the compressive strength at different curing times. b. Using an Excel sheet, plot the relationship between curing time and compressive strength. Label all axes and curves. c. Comment on the effect of curing time on the compressive strength. d. What is the approximate ratio between the compressive strengths at 7 days and 28 days? e. What is the approximate ratio between the compressive strengths at 28 days and 180 days?
A materials engineer is working in a research project to evaluate the effect of one type of admixture on the compressive strength of concrete. He tested eight mortar cubes made with admixture and eight others without admixture after 28 days of curing. The compressive strengths of cubes in psi with and without admixture are shown in Table P6.40.Using the statistical t-test, is there a significant difference between the meansof the compressive strengths of the two cement mortars at a level of signifi-cance of 0.10?
Determine the tensile steel ratio of a singly reinforced concrete beam for the following conditions using concrete strength f’c = 21 MPa and steel yield strength fy = 420 MPa. if the tensile strain is set as 0.009 upon crushing of concrete at a strain of 0.003. = [rr] (5 decimal places)
You are building a single family residence and are using 2x6 stud walls to build it. You don't have any existing testing data or standard deviation on 2x6 wood. However, you do have access to testing equipment and you test 30 2x6's that determine the mean compressive strength is 2000psi and standard deviation of the sample is 600psi. a) Use a 't-distribution', determine the 99% lower bound for the distribution of the sample data(i.e one trail) and explain your value.
Determine the tensile steel ratio of a singly reinforced concrete beam for the following conditions using concrete strength f’c = 28 MPa and steel yield strength fy = 420 MPa. if the tensile strain is εs = fy/Es upon crushing of concrete at a strain of 0.003. = ___ (5 decimal places)
The specified concrete strength for a new building is 5000 psi. Calculate the required average for the concrete (a) if there are no prior test results for concrete with a compressive strength within 1000 psi of made with similar materials, (b) if 20 test results for concrete with made with similar materials produce a sample standard deviation ss of 560 psi, and (c) if 30 tests with made with similar materials produce a sample standard deviation ss of 540 psi.
Slump is the measure of concrete consistency and fluidity. Explain the indication of true slump, shear slump and collapse slump in the slump test with the aid of suitable sketches.
Determine the tensile steel ratio of a singly reinforced concrete beam for the following conditions using concrete strength f’c = 21 MPa and steel yield strength fy = 420 MPa. 16. if the tensile strain is εs = fy/Es upon crushing of concrete at a strain of 0.003. = [r] (5 decimal places)
Three 150 mm * 300 mm concrete cylinders with water to cement ratios of0.4, 0.6, and 0.8, respectively. After curing for 28 days, the specimens weresubjected to increments of compressive loads until failure. The load versusdeformation results were as shown in Table P7.26. Assuming that the gauge length is the whole specimen height, it is required todo the following:a. The compressive stresses and strains for each specimen at each loadincrement.b. Plot stresses versus strains for all specimens on one graph.c. The ultimate strength for each specimen.d. The modulus of elasticity as the secant modulus at 40% of the ultimatestress for each specimen.e. The strain at failure for each specimen.f. The toughness for each specimen.g. Comment on the effect of increasing the water–cement ratio on thefollowing:i. Ultimate strengthii. Modulus of elasticityiii. Ductilityiv. Toughness. Curves may be approximated with a series of straight lines.