Exam 01 Flashcards
In regards to the entity which has authority over enforcing building codes, the acronym AHJ most nearly stands for:
Authority Having Jurisdiction
(T/F) The recorded wind speed during Hurricane Michael exceeded the design wind speed as specified by the AHJ.
True
All of the following are considered a dead load except:
Occupants
Weight of structural members
All of the above
Weight of permanent non-structural components
Occupants
In un-reinforced concrete ductile or brittle?
Brittle
Define slump and why it is important for concrete construction:
Work-ability of concrete ***
What does the symbol f’c stand for?
Compressive strength of concrete
(T/F) The maximum moment on a continuous beam with a uniformly distributed load occurs at the first interior support.
True
The maximum shear on a simply supported beam with a uniformly distributed load occurs at which location on the beam:
At the supports
The maximum moment on a simply supported beam with a uniformly distributed load occurs at which location on the beam:
mid-span
(T/F) The code specifies minimum flexural reinforcement but not maximum.
False
On a continuous beam with uniformly distributed loading, the flexural moment is greatest at:
First interior support
What are the likely consequences of adding too much water (more than the design mix w/cm ratio) to a concrete mix?
Reduced compressive strength (f’c)
Increase amount of shrinkage cracking.
(T/F) Reinforcement covers dictated by structural drawings are minimums and can be increased at the contractor’s options without detrimental effects.
False
(T/F) Steel shear reinforcement (stirrups) is required in all concrete flexural members regardless of the member type, demand and shear capacity of the concrete.
False
Per the 03 30 00 Cast-in-Place Concrete Specification, concrete shall not be placed when the outside air temperature is XXXX°F or less unless cold weather concreting practices are followed.
40
The reason for ACI 318 specifying maximum aggregate size in concrete mix design is most nearly:
To facilitate placement of concrete around the reinforcement without honeycombing due to blockage by closely spaced reinforcement.
Given a project in which only (1) sample for strength tests is required, how should the sample concrete be selected?
Random basis
Special inspections for concrete construction such as inspection of formwork is required by the IBC on all commercial projects.
False
(T/F) Concrete is strong in tension but weak in compression.
False
(T/F) Elastic shortening of concrete is an example of a pre-stress loss that occurs immediately.
True
(T/F) Submitals as opposed to RFI’s become a part of the contract documents and thus it is important to make any major changes to the construction documents within a submittal.
False
All of the following are example of submittals related to reinforced concrete except:
Erection drawings
Mix design
Reinforcement placement drawings
Curing compound product data
Erection drawings
If a concrete sample has a higher slump than per the approved mix design, which of the following is least likely to be the cause:
Too much cement.
(T/F) A concrete mix with a w/c ratio of 0.55 is more likely to have numerous shrinkage cracks then a mix with a w/c ratio of 0.45.
True
On a continuous beam with uniformly distributed loading, the flexural moment is greatest at:
First interior support
The purpose of skin reinforcement which is required on deep beams can best be described as:
To control cracking in the section which is especially critical for deep beams in which the neutral axis is located far away from the tension side of the beam.
According to the American Concrete Institute, who is responsible for providing a concrete cylinder cure box at the job site?
Contractor
The strength reduction factor for a concrete section controlled by flexure is 0.9 where for compression it is 0.75, what is best explanation for the reason between the different factors.
A concrete member that fails via flexure will provide greater warning signs of the overload than if it fails by shear.
(T/F) Increasing the concrete compressive strength of a concrete beam has negligible effect on the ultimate capacity?
True
(T/F) Steel shear reinforcement (stirrups) is required in all concrete flexural members regardless of the member type, demand and shear capacity of the concrete.
False
According to the American Concrete Institute, who is responsible for obtaining concrete cylinders for testing of the compressive strength.
Owner’s Testing Agency
Given a conventionally reinforced concrete beam in which the shear demand (Vu) is greater than ½∅Vc, what is the minimum amount of steel shear reinforcement (Av, min) required per linear foot? (Given: Width = 12”, Height = 30”, Clear Cover = 2”, Fyt = 60,000 psi, f’c = 5,000 psi)
0.011 in2/ft
How many concrete cylinders must be taken for a single 28-day concrete compression test?
4
The concrete framing system for Francis Hall is most nearly described as:
One-way beam
The reason for ACI 318 specifying minimum tension reinforcement in concrete flexural members can best be described as:
To guarantee that the flexural strength of the reinforced member is larger than the uncracked concrete section, since if not, when the beam approached it’s failure load, there would not be warning signs of the impending failure.
According to the American Concrete Institute, who is responsible for Quality Control: taking actions to ensure that Work meets the requirements of the contract documents?
Contractor
Per ACI 318, what is the thinnest section allowed for a cantilevering non-prestressed beam that is spanning 10’?
15”
Given a concrete beam in which the shear demand (Vu) is greater than ½∅Vc, the shear capacity of the stirrups (Vs) is less than 4√(f’cbwd) and the depth to the tension reinforcement is 30”, the maximum spacing of the stirrups is most nearly.
15”
(T/F) Reinforcement covers dictated by structural drawings are minimums and can be increased at the contractor’s options without detrimental effects?
False
The reason for ACI 318 specifying maximum tension reinforcement ratios can best described as:
To ensure that the members fails via tension in the reinforcement, a ductile failure mode in lieu of crushing of the concrete which is not a ductile failure mode.
On a simply-supported beam with uniformly distributed loading, the shear is greatest at:
At the supports
(T/F) Increasing the concrete compressive strength of a short, non-sway, concrete column has negligible effect on the ultimate capacity?
False
(T/F) The design team (architect and/or structural engineer) can require more stringent inspections that required by the building code.
True
(T/F) Per the IBC, formwork is only required to be inspected periodically, however per the specification 03 30 00 Cast-in-Place Concrete, formwork is required to be inspected continuously.
True
(T/F) Concrete slump and air contents tests shall always be taken at the point of placement, since this is ultimately where the concrete will be placed. and best matches the field conditions.
False
(T/F) Once a contractor has received notification that he has passed inspection, the contractor is now relieved from the obligation to adhere to the construction documents.
False
(T/F) Per the IBC, inspections are required on every single concrete project that requires a commercial permit regardless of the size.
True
(T/F) Per the IBC, special inspection of the formwork for concrete construction is required to be continuous.
False
You are the contractor on a 4,000 SF restaurant project. The foundation will contain approximately 40 yards of concrete and will be poured in a single day. What is the minimum amount of samples for strength test specimen’s required per ACI 318?
0
(T/F) Per the IBC, special inspections are required on every concrete project that requires a commercial permit regardless of the size?
False
(T/F) A prestressed concrete double-tee is an example of a post tensioned member.
False
The purpose of mild reinforcement (rebar) in a post-tensioned flat slab in addition to the post-tensioning tendons is most nearly:
Due to varying loading and structural configurations it is not practical to entirely eliminate all tension in the slab thus mild reinforcement is added is regions where there tension will still be present in the slab. Also, continuous steel is required for integrity of the structure.
The eccentricity “e” of a prestressed members can best be described as:
The distance between the center of gravity of the tendons and the neutral axis of the member.
The following are examples of prestress losses in pre-tensioned members except.
Wobble
Given that f’c is 5,000 psi, what is the allowable compressive stress at the transfer design stage at the end support of a simply supported beam?
3,500 psi
At which stage in the life of a prestress member is the prestress force the highest and the concrete compressive strength the lowest?
Transfer
Pre-Tension
Pre-Cast
double tees, hollow-core planks, precast piles.
The steel reinforcement (tendons) used for pre-tensioned members is bonded. (5% tolerance)
Post-Tension
Cast in place
cast-in-place concrete slabs, beams, etc.
The steel reinforcement used for post-tensioned members can be bonded or unbonded. (10% tolerance)
Bonded
prestressing tendons permanently bonded to surrounding concrete, for post-tensioned concrete this is accomplished via grouting of the tendons. (normal rebar)
Unbonded
prestressing tendons allowed “free” longitudinal movement relative to the concrete, typically unbonded tendons are encased with plastic sheathing with a corrosion inhibiting grease
Types of Prestress Losses:
Elastic shortening of concrete (instant)
Long-term creep of concrete (over time)
Long-term shrinkage of concrete (over time)
long-term relaxation of stress in the prestressed tendons (overtime)
Anchor seating loss at transfer
Building Codes specify the (1)_______ legal design and construction requirements for a (2)__________
- minimum
2. given jurisdiction
Why are Building Codes used?
To prevent insure that building will not collapse. This does NOT mean that building will NOT suffer any damage.
Building Official
person responsible of reviewing documents. They are in charge of performing inspections.
Authority Having Jurisdiction (AHJ)
legal entity in charge of enforcing Building Codes
Deferred Submittal
Part of design submitted AFTER permit has been submitted
Primary Structural Frame
support building against gravity and environmental loads
SAMPLING
You must take samples after (1)____ and before (2)_____ of the load has been discharged.
- 10%
2. 90%
(T/F) Earthquake forces are a function of the building mass (weight) and stiffness, which means that if a building is located in a high seismic region it is preferable for the building to be heavy and stiff in order reduce earthquake loads on the structure.
False
All of the following effect the magnitude of wind loads on buildings except.
Height of building Weight of the building Topography surrounding site Size of building Location of building
Weight of the building
(T/F) A structure designed and constructed to the minimum requirements of the building should should not sustain structural damage during a design earthquake or wind event.
False
(T/F) Wind loads increase the higher up from ground surface they are, since their is a reduction is friction with the ground.
True
(T/F) Earthquake induced forces is an example of gravity loading on a structure.
False
(T/F) A structure design to the minimum requirements of the building code should not collapse when subjected to a minimum design earthquake or wind event.
True
Load factors are applied to loads acting on building to account for:
- Differences in material strength
- Variation in construction (poor construction)
- Approximations in design methodology
- Uncertainty in the magnitude and location of applied load
- To allow structural engineers to lower the rigor of structural analysis and design and thus remain more profitable.
Per the International Building Code, a fire station is required to be designed as what Risk Category?
IV
The exposure category (wind design) for Francis Hall is most nearly:
Exposure B
