Structural Depth - Component Design and Detailing
A reinforced concrete column has a cross-sectional area of 1000 in^2, and the steel area is 90 in^2. This section satisfies the ACI code requirements. True or false?
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In a reinforced concrete column with a cross-sectional area of 1000 in^2, what is the minimum steel area that is needed to satisfy the ACI code requirements?
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What is the area of steel per foot in a reinforced concrete section with steel stirrups #3 (0.11 in^2) per 2 ft? A. 0.33 in^2/ft B. 0.22 in^2/ft C. 0.11 in^2/ft D. 0.055 in^2/ft
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Oversized holes cannot be used in bearing-type bolted connection. True or false?
Answer: True Explanation: Oversized holes may be used in slip critical connections but cannot be used in bearing-type connections. Refer to AISC 360-10, Section J3.2, p. 16.1-121.
What is the definition of rx?
Answer: rx is the radius of gyration in x-axis. The radius of gyration is a geometric parameter. Explanation: Refer to NCEES FE Reference Handbook, v. 10.0.1, p. 287.
What is the critical compression stress for a steel member at KLr=120?
Answer: 15.7 ksi Explanation: Refer to "AISC Table 4-14" in the NCEES FE Reference Handbook, v. 10.0.1.
By what factor must computer maximum in-plane deflection of the diaphragm being analyzed (ΔMDD) be greater than the average drift of adjoined vertical elements of the seismic force-resisting system over the story below the diaphragm under consideration (ΔADVE) in order for the diaphragm to be considered a flexible diaphragm?
Answer: 2 ΔADVE > ΔMDD Explanation: Refer to ASCE 7-16, Section 12.3.1.3.
What is the steel area in a reinforced concrete rectangular cross-section with four bars of #9?
Answer: 41 = 4 in^2 Explanation: Refer to "ASTM Standard Reinforcement Bars" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the allowable shear stress in section W18×40 for LRFD, knowing that Fy=50 ksi?
Answer: Fvallowable= 0 .6Fy = 0.6(50ksi) = 30ksi Explanation: Refer to "Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the definition of Sx?
Answer: Sx is the elastic section modulus.
What is the definition of Zx?
Answer: Zx is the plastic section modulus.
What is the definition of ry?
Answer: ry is the radius of gyration in y-axis. Explanation: Refer to NCEES FE Reference Handbook, v. 10.0.1.
What is the strength reduction factor, ϕ, when the strain in steel is 0.0035?
Answer: ϕ=0.775 ϕ=0.9-0.9-0.65 0.005-0.002(0.005-0.0035)=0.775 Explanation: A linear interpolation between ϕ=0.65 at steel strain 0.002 and ϕ=0.9 at strain 0.005 determines the strength reduction factor, ϕ. According to ACI 318-14.Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1.
The strain in the extreme concrete fiber of a reinforced concrete beam section is 0.003 under uniform distributed load w. When the load is doubled, what is the strain in the extreme concrete fiber?
Answer: 0.003 Explanation: The maximum strain in the concrete is 0.003. The strain in the concrete at failure is 0.003, according to ACI 318-14. Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1
When using proper anchor reinforcement (stirrups, ties, etc.) to resist concrete breakout forces during anchor design, what is the maximum distance the anchor reinforcement can be from the anchor centerline?
Answer: 0.5 x hef Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Section R17.4.2.9 and Figure R17.4.2.9.
In a sway frame, what is the minimum value of effective length, K?
Answer: 1 Explanation: Refer to "Table C-A-7.2" in the NCEES FE Reference Handbook, v. 10.0.1.
For filled composite members, what percentage of the total composite cross section must be the cross-sectional area of the steel section?
Answer: 1% Explanation: Refer to AISC 360-10 Section I2.2a, page 16.1-87.
In a non-sway frame, what is the maximum value of effective length, K?
Answer: 1.0 Explanation: Refer to "Table C-A-7.1" in the NCEES FE Reference Handbook, v. 10.0.1, p. 286
What is the critical edge distance for headed studs, headed bolts, expansion anchors, and undercut anchors?
Answer: 1.5 × hef where hef is the effective embedment depth of the anchor Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Figure R17.4.2.1.
When designing shallow foundations, what is the minimum width of footing allowed by the 2015 IBC?
Answer: 12 in Explanation: Refer to the International Building Code, 2015 ed., Section 1809.4.
In a reinforced concrete column with a cross-sectional area 1200 in^2, what is the number of bars needed to satisfy the ACI code requirements? Use #9 (Ab=1in^2) .
Answer: 12 in^2 Explanation: According to ACI code, the minimum steel ratio is 1%. 12in^2(1200in^2)=0.01 Refer to "Short Columns" in the NCEES FE Reference Handbook, v. 10.0.1.
A steel column with length 28 ft is supported at the top, bottom, and mid height. What is the unbraced length?
Answer: 14 ft Explanation: The unbraced length is 14 ft. Refer to "Table C-A-7.1" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete section, the concrete cross-sectional area is 10000 in^2. What is the minimum required steel area for temperature and shrinkage?
Answer: 18 in^2 Explanation: Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
How many unknown forces are there on each truss joint?
Answer: 2 Explanation: There are two unknown forces on each truss joint, which are Fx and Fy. Refer to "Plane Truss" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the minimum age of concrete required for adhesive anchors to be installed?
Answer: 21 days Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Section 17.1.2.
What is the angle from the horizontal for a typical concrete breakout cone in tension?
Answer: 35° Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Figure R17.4.2.1.
When designing rigid deep foundations, what is the maximum ratio of the embedment depth of the element to its least horizontal dimension?
Answer: 6 or less Explanation: Refer to the International Building Code, 2015 ed., Section 1810.2.4.
When dealiing with concrete the value of the strength reduction factor for shear varies. True or false?
Answer: False Explanation: The value of the strength reduction factor for shear is ϕ=0.75. Refer to "Resistance Factors, ϕ" in the NCEES FE Reference Handbook, v. 10.0.1, p. 274.
A reinforced concrete slab is supported by four brick walls. The slab length is three times the slab width. How many main layers of steel reinforcements should be provided? A. One layer B. Two layers C. Three layers D. Four layers
Answer: A Explanation: The slab is a one-way slab because its length is greater than twice of its width. The total number of layers of steel reinforcements is four, two at the top and two at the bottom. The reinforced concrete one-way slab acts as a simply supported beam. The main steel reinforcement resists the bending moment, and there is no moment at the slab edge. Therefore, it is required to reinforce the slab with the main reinforcement layer at the bottom. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1. Therefore, there is one main layer parallel to the short direction on the bottom, and the other three layers (at the top parallel to the short direction, a layer at the top, and a layer at the bottom parallel to the long direction) are for temperature and shrinkage requirements.
Which section resists more bending moments? 1. W12×72, Zx = 108 in^3 2. W16×57, Zx = 105 in^3 3. W18×50, Zx = 101 in^3 4. W21×48, Zx = 107 in^3
Answer: A Explanation: Mn=FyZx=108Fy. The section with larger Zx resists more moments. Refer to "Beams" in the NCEES FE Reference Handbook, v. 10.0.1.
A doubly symmetric compact section W16×67 is bent about its major axis. What is the maximum value of Mn? Given, Fy=50ksi Zx=130in^3 Sx=117in^3 Zy=35.5in^3 Sy=23.2in^3 A. Mn = 130Fy B. Mn = 117Fy C. Mn = 35.5Fy D. Mn = 23.2Fy
Answer: A Explanation: Mn=FyZx=130Fy. The major axis is x. Refer to "Beams" in the NCEES FE Reference Handbook, v. 10.0.1.
The designed shear capacity of a reinforced concrete beam section is Vn=1000 k. What is the maximum shear force Vu can be carried? A.750 k B.850 k C.900 k D.1000 k
Answer: A Explanation: Vu=750k The strength reduction factor of shear is ∅=0.75 Vu=∅Vn=0.75(1000)=750k Refer to "Beam-Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the rebar spacing for the main reinforcement in a 12 in thick one-way reinforced concrete slab? fy=60ksi. A. The main reinforcement distribution is #4 each 8 in B. The main reinforcement distribution is #4 each 1 ft C. The main reinforcement distribution is #4 each 1.5 ft D. The main reinforcement distribution is #4 each 2 ft
Answer: A Explanation: According to ACI318-14, the maximum spacing between the main rebars is the smaller of 3h or 18 in. 3h=3(12)=36 in=3 ft or 18 in=1.5 ft. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1. According to ACI 7.1.1, the minimum area steel is: Asmin=0.0018bh for fy=60 ksi Asmin =0.0018(12)(12)=0.2592 in^2/ft The area of steel for bar size #4/8in is: As=0.2 in^2(12in/ft)/8in =0.3 in^2/ft > Asmin. It is possible to be a correct answer that satisfy ACI-code The area of steel for bar size #4/1ft is: As=0.2 in^2 < Asmin It is not possible to be a correct answer because it does not satisfy ACI code. The area of steel for bar size #4/1.5ft is: As=0.2 in^2 /1.5 ft= 0.133 in2 < Asmin It is not possible to be a correct answer because it does not satisfy ACI code. The area of steel for bar size #4/2ft is: As=0.2 in^2 /2 ft= 0.1 in^2 < Asmin It is not possible to be a correct answer because it does not satisfy ACI code. Choice A is the only choice that satisfy ACI code. Choice A is the correct answer.
What is the difference or similarity between tension-controlled failure and compression-controlled failure? A. Tension-controlled failure provides warning before the failure while compression-controlled failure does not show any warning prior to the failure. B. Compression-controlled failure provides warning before the failure while tension-controlled failure does not show any warning prior to the failure. C. Both the tension-controlled failure and compression-controlled failure show a warning prior to the failure. D. Both the tension-controlled failure and compression-controlled failure do not show any warning prior to the failure.
Answer: A Explanation: Because steel is a ductile material, the tension-controlled failure shows a warning before the failure occurs while concrete is a brittle material that does not show any warning prior to the failure when it is the compression-controlled failure.According to ACI 318-14. Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1.
In a one-way reinforced concrete slab, which statement is incorrect? A. The direction of the temperature reinforcement is parallel to the short dimension of the slab. B. The direction of the temperature reinforcement is perpendicular to the main reinforcement. C. The direction of the temperature reinforcement is perpendicular to the short dimension of the slab. D. The direction of the temperature reinforcement is parallel to the long dimension of the slab.
Answer: A Explanation: In a one-way reinforced concrete slab, the direction of the temperature reinforcement is perpendicular to the main reinforcement and parallel to the long dimension of the slab. Refer to Section 7.7.6 of ACI 318-14.
What is the relation between the compression force resisted by the concrete and the tensile force resisted by the steel bars? A. The compression force that is resisted by the concrete is equal to the tensile force that is resisted by the steel bars with opposite direction. B. The compression force that is resisted by the concrete is greater than the tensile force that is resisted by the steel bars. C. The compression force that is resisted by the concrete is less than the tensile force that is resisted by the steel bars. D. The summation of the compression force that is resisted by the concrete and the tensile force that is resisted by the steel bars is equivalent to the bending moment.
Answer: A Explanation: The reinforced concrete section resists the bending moment by transforming the moment into a pair of forces as tension and compression. These two forces are equal.
In a reinforced concrete column, if the steel ratio exceeds the ACI code limit, what is the alternative design solution? A. Increase the concrete dimensions B. Reduce the number of bars C. Decrease the concrete dimensions D. Increase the number of bars
Answer: A Explanation: To maintain steel ratio below 8%, the cross-sectional dimensions of concrete must be increased. Refer to "Design Column Strength, Tied Columns" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the definition of a two-way shear?
Answer: A two-way shear is a punching shear at a reinforced concrete element due to the concentrated load that is applied to a smaller area of the element forming a cone failure. Explanation: Refer to "Beam - Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the ratio of depth of a rectangular stress block to the neutral axis depth if the compressive strength of concrete, f'c is 6 ksi? A. 0.65 B. 0.75 C. 0.80 D. 0.85
Answer: B Explanation: β1=0.85-0.05f'c-4 If 4 ksi ≤ f'c ≤ 8 ksi β1=0.85-0.056-4=0.75 Refer to "Design of Reinforced Concrete Components (ACI 318-14)" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete beam that is designed to resist shear, what is the relation between the nominal shear capacity, Vn, and the factored shear force, Vu? A. The factored shear force, Vu, is greater than the nominal shear capacity, Vn B. The factored shear force, Vu, is less than the nominal shear capacity, Vn C. The factored shear force, Vu, is twice the nominal shear capacity, Vn D. The factored shear force, Vu, is not related to the nominal shear capacity, Vn
Answer: B Explanation: ϕVn ≥ Vu Refer to "Beam - Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
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Answer: B Explanation: Refer to "Live Load Reduction" in the NCEES FE Reference Handbook, v. 10.0.1.
In a concrete beam design, the concrete above the neutral axis (on the compression side) of a reinforced concrete section: A. does not participate to resist any stresses. B. resists the compression stress that is produced due to the bending moment. C. resists the tensile stress that is produced due to the bending moment. D. resists the bending moment.
Answer: B Explanation: The concrete resists the compression stress that is produced due to the bending moment.
What is the minimum strain in flexural steel reinforcements at the tension-controlled section? A. 0.002 B. 0.005 C. 0.004 D. 0.003
Answer: B Explanation: The minimum strain in the steel is 0.005, according to ACI 318-14 Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1.
In a one-way reinforced concrete slab supported by four brick walls. How many layers of steel reinforcements should be provided? A. One layer B. Two layers C. Three layers D. Four layers
Answer: B Explanation: The reinforced concrete one-way slab acts as a simply supported beam. The main steel reinforcement resists the bending moment, and there is no moment at the slab edge. Therefore, it is required to reinforce the slab with the main reinforcement layer at the bottom and the steel reinforcement layer for temperature is perpendicular to the main reinforcement on the same layer. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
In an I-shaped steel section, which part of the section resists the vertical shear? A. The area of the two flanges and the web 2(tf×bf)+(d×tw) B. The area of the web d×tw C. The area of the bottom flange tf×bf D. The area of both flanges 2(tf×bf)
Answer: B Explanation: The vertical shear stress is resisted by the web area (d×tw). Refer to "Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
Why are steel stirrups used in a reinforced concrete section? A. The steel bars are insufficient to resist the bending moment B. The concrete shear capacity is insufficient to resist the shear force C. The concrete in Whitney block stress is insufficient to resist the compression stress D. To provide sufficient development length
Answer: B Explanation: When the concrete shear capacity is insufficient to resist the shear force, it is required to use steel stirrups.
What is the minimum length of a two-way reinforced concrete slab if its width is 10 ft? A. 20 ft B. 10 ft C. 15 ft D. 5 ft
Answer: B If the is slab supported on all four edges, it is considered as two-way slab if the ratio of its length to its width is between 1 and 2. The slab length is equal or longer than the slab width. The minimum slab length is 10 ft is satisfying the ratio of two-way slab. 10/10 between 1 and 2. Explanation: Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.1.
What is the value of β1 in reinforced concrete section if the concrete compressive strength f'c is 3.5 ksi? A. β1=0.75 B. β1=0.80 C. β1=0.85 D. β1=0.90
Answer: C Explanation: At f'c ≤ 4ksi, β1=0.85 Refer to "Design of Reinforced Concrete Components (ACI 318 -14)" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete column with cross-sectional area of 500 in2, if the steel ratio is 2%, what is the area of steel? A. 5 in^2 B. 2 in^2 C. 10 in^2 D. 0.02 in^2
Answer: C Explanation: The area of steel is 002500 = 10 in^2. Refer to "Design Column Strength, Tied Columns" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the relation between the nominal moment capacity and the design moment capacity? A. The design moment capacity equals the nominal moment capacity multiplied by the reduction factor, ϕ=0.9 B. The design moment capacity equals the nominal moment capacity multiplied by the reduction factor, ϕ=0.65 C. The design moment capacity equals the nominal moment capacity multiplied by the reduction factor, ϕ varies from 0.65 to 0.9 D. The design moment capacity equals the nominal moment capacity
Answer: C Explanation: According to ACI 318-14, the design moment capacity equals the nominal moment capacity multiplied by the reduction factor, ϕ varies from 0.65 to 0.9. Refer to "Beam - Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
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Answer: C Explanation: Refer to "Live Load Reduction" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the relation between the effective depth of a beam and its total height if the beam cross-section has one steel layer? A. The beam total height is the summation of the effective depth, the cover thickness, and the diameter of the steel bar. B. There is no relation between the effective depth of a beam and its total height. C. The beam total height is the summation of the effective depth, the cover thickness, and the radius of the steel bar. D. The beam total height is the summation of the effective depth and the cover thickness.
Answer: C Explanation: The beam total height is the summation of the effective depth, the cover thickness, and the radius of the steel bar. According to ACI 318-14. Refer to "Unified Design Provisions" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the maximum width of a one-way reinforced concrete slab if its length is 30 ft? A. The maximum slab width is 6 ft B. The maximum slab width is 10 ft C. The maximum slab width is 14 ft D. The maximum slab width is 26 ft
Answer: C Explanation: The maximum slab width is 14 ft. Choice A: Length to width ratio is 306=5>2 Choice B: Length to width ratio is 3010=3>2 Choice C: Length to width ratio is 3014=2.14>2 Choice D: Length to width ratio is 3026=1.875<2 Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete section, the concrete cross-sectional area is 10000 in^2. How many #9 steel bars are required for temperature and shrinkage? (area of one bar #9 is 1 in^2) A. 10 B. 15 C. 18 D. 20
Answer: C Explanation: The minimum steel ratio is 0.0018. Number of bars #9 is 18. Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
In a concrete beam design, the steel bars (on the tension side) of a reinforced concrete section: A. do not participate to resist any stresses. B. resist the compression stress that is produced due to the bending moment. C. resist the tensile stress that is produced due to the bending moment. D. resist the bending moment.
Answer: C Explanation: The steel bars resist the tensile stress that is produced due to the bending moment.
A concrete column is subjected to a moment M 1 at the top and another moment M 2 at the bottom. What are the values and directions of the moments to produce a double curvature on the column's deflected shape? A. M1 = 40 kft counterclockwise and M2 = 60 kft clockwise B. M1 = 40 kft clockwise and M2 = 60 kft counterclockwise C. M1 = 40 kft counterclockwise and M2 = 60 kft counterclockwise D. M1 = 40 kft clockwise and M2 = 0 kft
Answer: C Explanation: When the moments at the column ends are in the same direction, the deflected shape of the column is double curvature. Refer to NCEES FE Reference Handbook, v. 10.0.1.
What is the design flexural strength for a doubly symmetric compact I-shape member bent about its major axis? Given, Mn = 100 kft. A. 65 kft B. 75 kft C. 85 kft D. 90 kft
Answer: D Explanation: ∅b=0.9. ∅bMn = 0.9(100 kft) = 90 kft Refer to "Beams" in the NCEES FE Reference Handbook, v. 10.0.1.
In which cross-sectional shape is the slenderness ratio of a column equal in both directions x and y? A. W shape B. Rectangular cross-sectional shape C. T-section shape D. Square cross-sectional shape
Answer: D Explanation: In a square cross-sectional shape, the value of rx and ry are exactly the same. Therefore, the slenderness ratios are equal in both directions. Refer to NCEES FE Reference Handbook, v. 10.0.1.
Which of the following is a one-way reinforced concrete slab? A. The slab length is 16 ft and the width is 10 ft B. The slab length is 20 ft and the width is 16 ft C. The slab length is 16 ft and the width is 16 ft D. The slab length is 16 ft and the width is 6 ft
Answer: D Explanation: Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
How can one compute the Whitney Stress Block depth, a? A.By calculating the tensile force, Ts=Asfy B. By calculating Cc/a=0.85f'cb C. By setting the tension force, Ts, equal to the compression force, Cc, and solve for Whitney Stress Block depth, a. D. All of the above
Answer: D Explanation: The Whitney Stress Block depth can be computed as below: Step 1: Calculate the tensile force Ts=Asfy Step 2: Calculate Cc/a Step 3: Set the tension force, Ts, equal to the compression force, Cc, and solve for Whitney Stress Block depth, a.
What are the parameters on which concrete shear capacity depends? A. Effective depth of concrete, d B. Beam width, b C. Compressive strength of concrete, f'c D. All of the above
Answer: D Explanation: The concrete shear capacity equation is: Vc=2f'cbd Refer to "Beam - Shear" in the NCEES FE Reference Handbook, v. 10.0.1, p. 274.
The value of the strength reduction factor, ϕ, depends on the strain in the concrete at failure. True or false?
Answer: False Explanation: The value of the strength reduction factor, ϕ, depends on the strain in the steel at failure. According to ACI 318-14. Refer to "Beam - Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete column, if the steel ratio is below the ACI code limit, what is the alternative design solution? A. Increase the concrete dimensions B. Reduce the number of bars C. Decrease the concrete dimensions D. Increase the number of bars
Answer: D Explanation: The number of steel bars must be increased to maintain steel ratio not less than 1%. Refer to "Design Column Strength, Tied Columns" in the NCEES FE Reference Handbook, v. 10.0.1.
In a concrete beam design, the reinforced concrete section: A. does not participate to resist any stresses. B. resists the compression stress that is produced due to the bending moment. C. resists the tensile stress that is produced due to the bending moment. D. resists the bending moment.
Answer: D Explanation: The reinforced concrete section resists the bending moment by transforming the moment into a pair of forces as tension and compression.
Each truss member can resist bending moment. True or false?
Answer: False Explanation: A beam can resist bending force while a truss member cannot resist any moment.
Any truss member can carry shear force. True or false?
Answer: False Explanation: A beam can resist shear force while a truss member cannot resist any shear force.
A reinforced concrete section is subjected to factored shear force at distance d from the face of the support Vu=400k including the beam self-weight. The concrete shear capacity is ∅Vc=820k. Steel stirrups are required. True or false?
Answer: False Explanation: According to ACI code 318-14, if Vu<∅Vc2, the concrete capacity can resist the shear without using steel stirrups. Steel stirrups are not required. Refer to "Beam-Shear" in the NCEES FE Reference Handbook, v. 10.1.
When considering adhesive anchor systems, adhesive bond strength is higher in cracked concrete. True or false?
Answer: False Explanation: Bond strength is higher in uncracked concrete. Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Section R17.4.5.2b
If the support conditions for a steel column are similar in both weak and strong directions, the slenderness ratio is the same in both directions x and y. True or false?
Answer: False Explanation: Due to the difference between rx and ry in any steel section, the slenderness ratios are different. Refer to "Table C-A-7.1" in the NCEES FE Reference Handbook, v. 10.0.1
In a sway frame, the slenderness ratio of a concrete column is 24. This column satisfies the ACI code requirements. True or false?
Answer: False Explanation: In a sway frame, the maximum slenderness ratio of a concrete column is 22. Refer to "Graph A.11" in the NCEES FE Reference Handbook, v. 10.0.1.
In a reinforced concrete section, the ratio of steel area to concrete cross-sectional area is 0.0014. This section satisfies the ACI-code requirements about minimum steel. True or false?
Answer: False Explanation: Refer to "Beam-Flexure" in the NCEES FE Reference Handbook, v. 10.0.1.
In a two-way reinforced concrete slab, if the main steel area is less than the area of steel for the temperature reinforcement, the steel area of temperature reinforcement must be reduced to be less than the main steel reinforcement. True or false?
Answer: False Explanation: Steel area of temperature reinforcement represents the minimum steel reinforcement. Therefore, if the main steel area is less than the area of steel for the temperature reinforcement, the main steel area must be increased to be not less than the area of steel for the temperature reinforcement. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
In a two-way reinforced concrete slab supported by two parallel brick walls, there is no need for temperature reinforcement. True or false?
Answer: False Explanation: Temperature reinforcement should be maintained in the directions that do not require structural reinforcements. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
When the longitudinal space in a reinforced concrete beam is limited, there are no alternative options to provide development length. True or false?
Answer: False Explanation: The alternative options procide the development length in a shorter distance either 90° or 180° bent bar near the terminal end of the bar.
In a two-way reinforced concrete slab, the top main reinforcement is designed based on the bending moment on the midspan. True or false?
Answer: False Explanation: The bending moment in the slab edges causes tension stress on the top of the slab and compression stress on the bottom. Therefore, the main reinforcement should be provided on the top of the slab to resist the tension stress. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
The equation to calculate the compression block, α, of a T-section is the same as that for the rectangular section. True or false?
Answer: False Explanation: The equation to calculate the compression block, α, of a T-section is the same as that for the rectangular section when α ≤ hf, while when α>hf, the statement is false. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1, p. 274.
The lateral torsional buckling modification factor, Cb=1, when the moment is non-uniform. True or false?
Answer: False Explanation: The lateral torsional buckling modification factor for uniform moment diagrams is: Cb=1, while for non-uniform moment: Cb=12.5Mmax2.5Mmax+3MA+4MB+3Mc Where, MA, MB, MC are the absolute value of maximum moments at L4, L2, 3L4, respectively. Refer to "Lateral Torsional Buckling" in the NCEES FE Reference Handbook, v. 10.0.1.
The shear stress is the maximum at the extreme fiber of the cross-section, and minimum at the mid height of the section. True or false?
Answer: False Explanation: The shear stress is the minimum at the extreme fiber of the cross-section and maximum at the mid height of the section. Refer to "Shear" in the NCEES FE Reference Handbook, v. 10.0.1.
When the reinforcement bars are only on the top of a cross-sectional concrete beam, the support conditions of this beam are pined-pined supports. True or false?
Answer: False Explanation: The top reinforcement means that the tensile stress is on the top face of the beam. The beam is a cantilever with a fixed support. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
The strong axis in a steel section is the x-axis. True or false?
Answer: True Explanation: Refer to "Table 1.1, W shapes dimensions and properties" in the NCEES FE Reference Handbook, v. 10.0.1.
A concrete column subjected to a moment equals 120k clockwise at the top and 60k counterclockwise at the bottom. The deflected shape of the column is double curvature. True or false?
Answer: False Explanation: When the moments at the column ends are in the opposite directions, the deflected shape of the column is single curvature.
In a concrete beam design, the concrete below the neutral axis (on the tension side) of a reinforced concrete section:
Answer: Ignored, or it is not participated to resist any stresses. Therefore, it is inactive and ignored. In fact, the concrete does not resist any tensile stresses
What is compression-controlled failure?
Answer: In a reinforced concrete section, compression-controlled failure occurs when the concrete fails under compression before the failure of the steel bars.
What is tension-controlled failure?
Answer: In a reinforced concrete section, tension-controlled failure occurs when the steel bars fail under tension before the failure of the concrete.
What is the theoretical effective length factor, K, in a column with free rotation and free translation at top and a fixed support at bottom?
Answer: K= 2.0 Explanation: Refer to "Table C-A-7.1" Page 16.1-511 AISC 14th edition.
What is the main differentiation between high-strength bolt groups A and B?
Answer: Material strength Explanation: According to AISC 360-10, Section J3.1, p. 16.1-118, group B bolts have a higher tensile stress than group A bolts. Refer to the AISC Steel Construction Manual, 14th ed., Part 2, Table 2-6.
What is the name of the installation condition where bolts are tightened to bring the connected plies in firm contact?
Answer: Snug-tight condition Explanation: Refer to AISC 360-10, Section J3.1, p. 16.1-118.
What is the cover thickness in a reinforced concrete beam section?
Answer: The cover thickness is the distance from the extreme tension fiber in a beam section to the outer surface of the reinforcing steel. According to ACI 318-14. Refer to "Unified Design Provisions" in the NCEES FE Reference Handbook, v. 10.0.1, p. 276.
Based on the strain in steel, how can the designer determine if the section is in compression-controlled failure?
Answer: The designer can determine that the section is in compression-controlled failure when the strain in steel is less 0.002. According to ACI 318-14. Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1.
Based on the strain in steel, how can the designer determine if the section is in tension-controlled failure?
Answer: The designer can determine that the section is in tension-controlled failure when the strain in steel is greater than 0.005. According to ACI 318-14. Refer to "Strain Conditions" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the development length in a reinforced concrete section?
Answer: The development length, ld, is the length of the steel bar that is required to provide bond strength and transfer the stress from the reinforcing steel to the surrounded concrete.
What is the unbraced length in steel section?
Answer: The distance between the brace points on the compression flange, Lb. Explanation: Refer to "Lateral Torsional Buckling" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the effective depth of a beam?
Answer: The effective depth, d, is the distance from the extreme compression fiber in a beam section to the centroid of the reinforcing steel on the tension zone. According to ACI 318-14. Refer to "Unified Design Provisions" in the NCEES FE Reference Handbook, v. 10.0.1, p. 276.
For cast-in-place deep foundations supporting structures assigned to Seismic Design Categories D, E, and F, what is the maximum spacing of transverse reinforcement?
Answer: The least of 12 longitudinal bar diameters, one-half the least dimensions of the element, or 12 in Explanation: Refer to the International Building Code, 2015 ed., Section 1810.3.9.4.2.
What is the definition of Lr?
Answer: The maximum unbraced length in a steel section that results in first yield with residual stresses is Lr. Explanation: Refer to "Lateral-Torsional Buckling" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the maximum unbraced length in I-beam?
Answer: The maximum unbraced length, Lp, is the distance between the brace points on the compression flange, which results in the plastic moment for the beam. Explanation: Refer to "Lateral Torsional Buckling" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the nominal hole diameter in a steel structure?
Answer: The nominal hole diameter is the bolt diameter + 1/16 in. Explanation: Refer to "Tension Members" in the NCEES FE Reference Handbook, v. 10.0.1.
In a one-way reinforced concrete slab, what is the purpose of the main reinforcement?
Answer: The purpose of the main reinforcement is to resist the bending moment that is produced from the applied load. Explanation: Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
In a one-way reinforced concrete slab, what is the purpose of the secondary reinforcement
Answer: The purpose of the secondary reinforcement is to reduce the chance of the concrete cracking due to temperature variation and shrinkage. Explanation: Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
For each column, there are two different slenderness ratios. True or false?
Answer: True Explanation: KLrx and KLry
The minimum development length depends on concrete cover thickness and steel bar spacing. True or false?
Answer: True Explanation: According to ACI 318-14, Section 25.4.2.1. Refer to "Design of Reinforced Concrete Components" in the NCEES FE Reference Handbook, v. 10.0.1.
In a one-way reinforced concrete slab, the main reinforcement is parallel to the short dimension of the slab. True or false?
Answer: True Explanation: In a one-way reinforced concrete slab, the slab width is considered as the slab span. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
When designing anchors and their attachments within structures assigned to Seismic Design Categories C, D, E, and F, the anchor or group of anchors should be designed for maximum tension and shear obtained from design load combinations that include seismic load E increased by overstrength factor Ω0. True or false?
Answer: True Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Section 17.2.3.4.3d and 17.2.3.5.3d.
Testing is required for post-installed anchors when used in concrete with fcʹ > 8,000 psi. True or false?
Answer: True Explanation: Refer to ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Section 17.2.7.
In a two-way reinforced concrete slab, the bottom main reinforcement is designed based on the bending moment on the midspan. True or false?
Answer: True Explanation: The bending moment in the midspan causes tension stress at the bottom of the slab and compression stress at the top of the slab. Therefore, the main reinforcement should be provided on the bottom of the slab to resist the tension stress. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1
The equation to calculate the compression block, α, of an inverted T-section is the same as that for the rectangular section. True or false?
Answer: True Explanation: The inverted T-section is treated as a rectangular cross-section. Therefore, the equation to calculate the compression block, α, of an inverted T-section is the same as that for the rectangular cross-section. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
A reinforced concrete slab with dimensions 10 ft×10 ft is supported by two parallel brick walls. This slab is considered a one-way slab. True or false?
Answer: True Explanation: The reason to consider this slab as a one-way slab is because it is supported from two sides only. Refer to "Singly Reinforced Beam" in the NCEES FE Reference Handbook, v. 10.0.1.
When considering adhesive anchor systems, adhesive bond strength is directly proportional to anchor diameter. True or false?
Answer: True Explanation: according to eq 17.4.5.2, they are directly proportional
A doubly symmetric compact section W16×67 is bent about its minor axis. What is the minor axis?
Answer: y Explanation: Refer to "Beams" in the NCEES FE Reference Handbook, v. 10.0.1.
What is the relation between the allowable shear stress and the allowable shear force in a W steel section? A .Shear force=Shear stress B .Shear force=Shear stress×A C .Shear force=Shear stress×A_f D .Shear force=Shear stress×A_w
Where: A is the area of W steel section Af is the flanges area of W steel section Aw is the web area of W steel section Answer: D Explanation: Refer to "Shear" in the NCEES FE Reference Handbook, v. 10.0.1