5.3 Steel Column Assignment 5 NAME:

Transcription

1 5.3 Steel Column Assignment 5 NAME: We will size a 16-foot-tall column that is pinned at bottom and top and is restrained against sway (lateral movement) at the top (so the effective length is 16 feet). The axial force will vary, to illustrate certain patterns of behavior. We will make observations regarding how the self-weight and structural efficiency of the column varies with the applied load. 1. Sizing the column as limited only by yielding of the material. A. Loading Condition 1 (light load): The column supports part of a light-weight metal roof that delivers the following compressive forces to the top of the column: P Dead =8.00K P Live =24.00K Standard steel pipe is manufactured in 35-KSI steel. a. What is the required cross-sectional area A as limited by the yield stress? b. What is the weight of a column with that cross-sectional area? Calculate by multiplying the cross-sectional area by the conversion factor: 3.40# Linear Foot 2 in of cross sectional area (This conversion factor is gotten from the following:. 490# D steel = 3 ft We want the weight of a piece of steel one foot long, with a cross-sectional area of one square inch. One cubic foot consists of 144 such columns of material. Therefore, the desired weight is 490#/144=3.40#, leading to the conversion factor 3.40# Linear Foot 2 in of cross sectional area ) Square steel tube is manufactured in 46-KSI steel. c. What is the required cross-sectional area A as limited by the yield stress? d. What is the weight of a column with that cross sectional area? Calculate by multiplying the cross-sectional area by the conversion factor noted above. Page 1

2 W-Flange steel columns of the sizes appropriate to this problem are manufactured in 50-KSI steel. e. What is the required cross-sectional area A as limited by the yield stress? f. What is the weight of a column with that cross sectional area? Calculate by multiplying the cross-sectional area by the conversion factor noted above. B. Loading Condition 2 (heavy load): The column supports part of a multistory building that delivers the following compressive forces to the top of the column. P Dead =85.00K P Live =170.00K Standard steel pipe is manufactured in 35-KSI steel. a. What is the required cross-sectional area A as limited by the yield stress? b. What is the weight of a column with that cross-sectional area? Square steel tube is manufactured in 46-KSI steel c. What is the required cross-sectional area A as limited by the yield stress? d. What is the weight of a column with that cross sectional area? W-Flange steel columns of the sizes appropriate to this problem are manufactured in 50-KSI steel. e. What is the required cross-sectional area A as limited by the yield stress? f. What is the weight of a column with that cross sectional area? Page 2

3 2. Sizing the column to resist both crushing and buckling, using standard tables. A. Loading Condition 1 (light load): The column supports part of a light-weight metal roof that delivers the following compressive forces to the top of the column: P Dead =8.00K P Live =24.00K Ф c P n, for steel pipe columns of various cross-sections and a. What is the lightest-weight standard pipe column in 36-KSI steel that will safely support the load? b. What does the pipe column weigh? c. By what factor is the weight of this column greater than the weight of the _ Ф c P n, for square steel tube columns of various cross-sections and d. What is the lightest-weight standard tube column in 45-KSI steel that will safely support the load? e. What does the standard tube column weigh? f. By what factor is the weight of this column greater than the weight of the _ Ф c P n, for W-Flange steel columns of various cross-sections and g. What is the lightest-weight W-Flange column in 50-KSI steel that will safely support the load? h. What does the W-Flange column weigh? Page 3

4 i. By what factor is the weight of this column greater than the weight of the _ B. Loading Condition 2 (heavy load): The column supports part of a multistory building that delivers the following compressive forces to the top of the column. P Dead =85.00K P Live =170.00K Ф c P n, for steel pipe columns of various cross-sections and a. What is the lightest-weight standard pipe column in 36-KSI steel that will safely support the load? b. What does the pipe column weigh? c. By what factor is the weight of this column greater than the weight of the _ Ф c P n, for square steel tube columns of various cross-sections and d. What is the lightest-weight standard tube column in 45-KSI steel that will safely support the load? e. What does the standard tube column weigh? f. By what factor is the weight of this column greater than the weight of the _ Ф c P n, for W-Flange steel columns of various cross-sections and g. What is the lightest-weight W-Flange column in 50-KSI steel that will safely support the load? Page 4

5 h. What does the W-Flange column weigh? i. By what factor is the weight of this column greater than the weight of the _ Comparison of results for light load and heavy load: Is the round pipe or the wide-flange more efficient under the light load? Is the round pipe or the wide-flange more efficient under the heavy load? Because this assignment requires a number of repetitive calculations students are encouraged to use excel to complete this exercise. Page 5