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CONCRETE
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CONCRETE
Untitled Flashcards
Study
1
Question
What is the effective moment of inertia denoted as in the ACI 318 code?
Answer
Ie
2
Question
In ACI 318, what does the effective moment of inertia account for?
Answer
Observations on Ie computation
3
Question
According to ACI 318, which factors are independent of the loading on the beam?
Answer
Icr, Ig, and Mcr
4
Question
How does the effective moment of inertia change with an increase in load on the beam?
Answer
Ie will decrease
5
Question
What is the relationship between load increase and the development of cracks in the beam according to ACI 318?
Answer
As load increases, more cracks will develop leading to reduced Ie
6
Question
What is staged loading in structures?
Answer
Staged loading is the application of Dead load D and live load L in stages on a structure.
7
Question
How is a concrete beam subjected to staged loading?
Answer
A concrete beam is first subjected to dead load and then further loaded by dead load plus live load in stages.
8
Question
What is the purpose of applying live load in staged loading?
Answer
The live load is applied to compute the deflection due to live load only, as some portion of the live load can be sustained for a period of time.
9
Question
What is the concept of staged loading in structures?
Answer
Staged loading is the application of Dead load (D) and live load (L) in stages, where the structure is first subjected to dead load and then further loaded by dead load plus live load.
10
Question
How can we determine the deflection caused by only load 3 in staged loading?
Answer
To determine the deflection caused by only load 3 in staged loading, we need to consider the loading history and the sequence of loading stages, such as 3-123-12-3, and analyze the deflection due to each stage of loading.
11
Question
Why is it challenging to compute the deflection caused by load 3 directly in staged loading?
Answer
It is challenging to compute the deflection caused by load 3 directly in staged loading because the beam never sees load 3 by itself, as it is subjected to a sequence of loading stages.
12
Question
What is the solution to computing the deflection due to live load only in staged loading?
Answer
To compute the deflection due to live load only in staged loading, the loading history and the sustained portion of the live load for a period of time need to be taken into account during the analysis of the beam's behavior under different loading stages.
13
Question
What are deflection limits in the ACI 318 code often based on?
Answer
Live load
14
Question
When is live load typically applied in relation to dead load in structural analysis?
Answer
After dead load is applied
15
Question
How can live load deflection be computed according to the text?
Answer
By using load factors (LL, DL, LL)
Untitled Flashcards
Study
1
Question
What is the Service Limit State Check for Deflection in a beam?
Answer
It involves determining the deflection under different loading conditions including immediate deflection due to live load, long-term time-dependent deflection due to creep and shrinkage of concrete, and total deflection.
2
Question
How is immediate/instantaneous deflection due to live load denoted in the expression for service limit state check for deflection?
Answer
It is denoted as L_DL_D in the expression.
3
Question
What additional deflection develops under sustained load in the service limit state check for deflection?
Answer
Under sustained load, the dead load portion of the live load contributes to additional deflection due to creep.
4
Question
What is the design load for a storage warehouse?
Answer
100% of its design load over its design life
5
Question
How is the total long term deflection computed?
Answer
Total long term deflection = Immediate deflection due to live load + Immediate deflection due to dead load + Immediate deflection due to sustained live load
6
Question
What does SL represent in the computation of long term deflections?
Answer
Sustained live load multiplier for infinite duration
7
Question
What is the time dependent factor used in the computation of long term deflections?
Answer
Duration multiplier for the duration of sustained live load
8
Question
What is the sustained load (w) on the beam?
Answer
40 kipft
9
Question
What is the duration of the sustained load on the beam?
Answer
12 months
10
Question
What is the distributed load (w_L) on the beam?
Answer
25 kipft
11
Question
What is the span length (L) of the beam?
Answer
24 ft
12
Question
What is the moment of inertia (I_g) of the beam?
Answer
18000 in^4
13
Question
What is the cracked moment of inertia (I_cr) of the beam?
Answer
9600 in^4
14
Question
What is the critical moment (M_cr) on the beam?
Answer
50 ft-kips
15
Question
What is the modulus of elasticity (E_c) of the beam material?
Answer
4030 ksi
16
Question
What is the total long term deflection of the beam shown below?
Answer
To be determined.
17
Question
What is the value of Ig for the beam?
Answer
18000 in^4
18
Question
What is the value of Icr for the beam?
Answer
9600 in^4
19
Question
What is the value of Mcr for the beam?
Answer
50 ft-kips
20
Question
What is the value of Ec for the beam?
Answer
4030 ksi
21
Question
Are ACI service limit state requirements met for the beam?
Answer
To be determined.
22
Question
What is the value of wd for the beam?
Answer
10 kip/ft
23
Question
What is the value of wl for the beam?
Answer
25 kip/ft
24
Question
What is the length of the beam (L)?
Answer
24 ft