Questions tagged [reinforced-concrete]

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31 views

How to design two reinforced concrete beams crossing each other at the same level?

If I have two beams of same stiffness and present at same level, how can i decide which beam is supporting the other beam? What would the moment diagram look like? How to design both the beams? How to ...
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0answers
22 views

Design of T-Beam

Please design a T-beam section size such that hf ≥ 125 mm, bw ≥ 200 mm, be ≥ 500 mm, d ≥ 300 mm, the concrete f'c strength is 25 MPa; the calculated concrete shear strength Vc that can be provided is ...
2
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1answer
27 views

How do hooks/bends cause bearing stresses in reinforced concrete?

Can someone please explain the exact mechanics of development of bearing stresses in concrete on account of bending of steel reinforcement and/or providing of hooks at the beam-column junction for ...
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1answer
23 views

Can anyone help me with the concept of bearing stresses in steel reinforcement in Reinforced Concrete?

When there is tension reinforcement(steel) embedded in concrete, does it not also undergo bearing stresses on account of the weight of the concrete and other forces which are acting above the steel? ...
2
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1answer
82 views

What is this circular metal object embedded in spalled concrete?

Consider the piece of spalled concrete shown in the attached image. It has spalled due to the corrosion of the reinforcement bar. There is a small circular piece of metal embedded within the spalled ...
7
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1answer
824 views

Design of transverse reinforcement in a wide beam

Besides satisfying nominal bar provision in the code, is there any special requirement in the provision of transverse reinforcement to ensure that the longitudinal reinforcement is fully effective in ...
1
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1answer
53 views

Dependency between load capacity for reinforced concrete slab and thickness

How does the load capacity for a reinforced concrete slab depend on the thickness of the slab? Example: Let's suppose that we have the following constants: concrete quality (including the maximum ...
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1answer
85 views

Reinforced mesh at different distance in a concrete slab?

Trying to determine some information regarding the reinforced concrete slabs (reinforced with mesh) in an apartment, by looking through the holes in the middle of the rooms for lights, I've come ...
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2answers
51 views

Concrete rebar cover requirements - Hook lift anchors

ACI 318 7.7 covers requirements for cover when designing rebar placement within concrete. However, they are for general components and makes no exceptions for small irregularities such as lifting hook ...
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0answers
62 views

Is it possible to measure the concrete workability by a mobile app one day? [closed]

After studying all methods that can measure the concrete slump, I found 62 devices that service this purpose at the same time these devices are expensive and not practical enough, for this reason the ...
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2answers
48 views

Concrete pad over filled, in-ground pool better with or without wall support?

We are currently having a project done in our backyard to: (1) fill an in-ground pool and (2) build a "sport court" (with a large concrete pad and some tiles) over top. The pool demolition ...
4
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2answers
426 views

In a reinforced concrete detail drawing what does 'reinforcement to be GK 60' mean?

Consider the following extract from a British reinforced concrete drawing from 1970: It states that 'REINFORCEMENT TO BE G.K 60. UNLESS STATED OTHERWISE' What is the meaning of GK 60? What property ...
4
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0answers
306 views

Conservative rebar dowel hole sizing and embedment depth

My question concerns the hole sizing and embedment depth of post installed rebar which is secured with epoxy mortar into a hole in a reinforced concrete slab. Hole diameter sizing My assumption #1 ...
3
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2answers
59 views

Concept design for an extension to a blanket raft slab

A blanket raft is a type of solid slab raft consisting of deeper ‘toe’ sections running around the edge of the foundation as well as a central deeper ‘beam-like’ section which offer rigidity to the ...
3
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1answer
585 views

How to design a reinforced concrete ship keel?

I am building a small ship (or very large sailboat) that will have a concrete ballast at the base of the keel. I am looking to increase the weight of the concrete (lb/ft3), but I also want to maximize ...
3
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1answer
56 views

Why is there a row of circular holes in this concrete beam?

The reinforced concrete beam (approximate dimensions 36" x 18") shown in the image below has a row of circular holes at 3/5ths of the height of the cross-section at approximately 300 mm centres. My ...
4
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2answers
66 views

The design of precast concrete— are they the same with cast-in situ design?

I am curious as to how different is precast concrete design than conventional cast-in situ reinforced concrete design as far as structural engineering is concerned. To my mind, they should be the ...
1
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1answer
95 views

Is it safe to slightly cut the edge of RCC column for passage of pipe in bathroom?

The RCC column was cut in my absence due to passage of pipe for bathroom fittings. The thickness is about 1.5 in. Will it hamper the stability of structure?
2
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0answers
141 views

Why do we use the strain-controlled test for the compressive strength of concrete?

As you all now, a typical stress-strain curve for concrete under compression can be seen in any reinforced concrete design textbook. The decreasing part of the curve (post-peak) can be obtained by ...
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2answers
13k views

Relative strength of wire mesh vs rebar for reinforcing a concrete slab

I have a friend who is German and he says that wire mesh is much stronger than steel bars (rebar) and is mandated in Germany for reinforcing concrete slabs. The question is, is that true, and why? ...
2
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1answer
48 views

Are the design load values in this floor determination table (span chart) inclusive or exclusive of the given floor weight (inherent dead load)?

So, I have been doing research into the use of Insulated Composite Concrete Forms (ICCFs) for small-scale construction, and that has led me to looking at the Rastra ICCF system, as it has been in ...
5
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2answers
6k views

What is the splice length for two reinforcement bars in tension of different diameter?

For reinforcing in concrete, anchorage / lap lengths are determined by the multiplying the diameter of the rebar with a factor. Generally a factor of 40-45 is accepted as the de-facto standard. ...
2
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0answers
64 views

Maximum allowable crack in Post Tension concrete

What is the maximum allowable crack size dimension in a post-tension concrete slab before it is considered a "structural" crack, in Arizona, USA? Is there a certain standard for this. I have tried ...
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2answers
150 views

Impact of having flexible electrical hose buried into the reinforced concrete slab

Given: a reinforced concrete two-way slab at about 160 mm (the edges are cantilevered between the concrete walls) the electricians buried the flexible electrical hose into the slab (red lines in the ...
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3answers
100 views

Does screed increase the slab tension capacity?

Does a screed applied over the slab increase the slab tension capacity? Somehow it's counter intuitive because adding weight on the slab should tension it, but do the slab and the screed behave as a ...
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3answers
76 views

Why not a reverse bending in the slab?

When I'm looking at images / videos about the load supported by reinforced concrete slabs, I always see a compression at the top of the slab in every point that varies from the center to the edges: ...
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0answers
20 views

Generating random samples for some concrete structural characteristics [closed]

I want to test a program that performs FRP concrete structural strengthening calculations according to a particular design code. As inputs for these calculation, there is existing concrete cross ...
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1answer
313 views

How do i find the effective length factor (k) for a column from this chart?

I need to find the effective length of a column (kl) from this chart which can be found in the "design of concrete structure" By Dr. Arthur Nilson. the question states "if Psi top is 1.5 and the ...
2
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3answers
86 views

Using electricity to heat up a slab through post-tension cables?

Would a passive and controlled amount of electricity fed through post-tension cables, heat up a slab, without ruining the dependability and health of the post-tension cables, and the concrete itself? ...
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1answer
83 views

Finding good and effective solution for overhead RCC slab spalling due to corrosion in Rebars [closed]

Please suggest some effective repair solution for spalling overhead slab due to high corrosion in rebars.
2
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1answer
215 views

How to perform SLS check with strut-and-tie method?

I am using strut-and-tie method to design a corbel. I noticed that Eurocode mentions strut-and-tie only in section 6, which is ultimate limit state design. How do I perform serviceability limit state ...
6
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3answers
1k views

How are loads transferred to bearing piles in a wall pier?

I've been working on the design of a reinforced concrete wall pier for a three-span bridge. I roughed out the design based on a number of example plan sets and now that I'm taking a crack at the ...
12
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3answers
3k views

Should I reject a concrete mix design for having too high of a compressive strength?

I usually design precast concrete members for the common concrete strength of f'c=4,000 psi at 28 days. Occasionally, a mix design will be submitted that has a very high strength. In one case, the mix ...
3
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0answers
103 views

Analysis method for two-way slab floor with central column

What method would be appropriate to analyze this concrete structure? A two-way rectangular concrete slab with walls and central column. I would like to understand how to model it with either yield ...
3
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1answer
646 views

Percentage area of steel for a retaining wall - standard formula doesn't make sense to me?

I'm looking at the usual UK/EU standards formula for the reinforcing steel area percentage, in a retaining wall. Essentially in "usual" cases it comes down to 0.13% of the cross-sectional area of Tw (...
3
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1answer
22 views

How to find resisting moment with rebars of different yield strengths?

When designing a concrete slab or rectangular beam, how would you compute the Mn value if there were two rows of rebars one with a yield strenght of 40 ksi and the other with the yield strenght at 60 ...
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1answer
557 views

Punching Shear in Slab?

Which dimensions of columns supporting flat slabs do not require a punching shear check (according to ACI code)?
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2answers
310 views

Why is this structurally sound?

While visiting Vancouver, Canada recently, I noticed there is a lot of construction for apartments and condos. Attached is a photo of one of many of those sites, and at these sites, I noticed ...
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0answers
99 views

Bonding steel plate to fiber cement sheet effectively

I've been trying to produce a cheap panel using fiber cement and zincalume sheet. There is a research paper that I read about bonding steel plate to concrete to increase their tensile strength by ...
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0answers
25 views

Difference Between minimum steel required in Slabs and Shear Walls

My question is very simple, I need to know why the minimum reinforcement for slabs is less than the minimum reinforcement required in Shear walls? What are the criteria and reasons to set minimum ...
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2answers
309 views

Is continuous beam design deemed “unsafe” by any code of practice/design practice for reinforced concrete building structures?

I am asking this because some of my engineer friends said that they won't want to analyze beam as continuous beam for RC building structures, because it is "unsafe" to do so, whether it has anything ...
3
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1answer
69 views

What is the definition of Ecm in equation 7.10 of EC2?

In the old British standard we use a time dependent modulus of elasticity of concrete to calculate crack width, which is usually about half of the 28-day Ec for long term modulus. In Eurocode EN 1992-...
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0answers
80 views

Clarification of cover definition in Eqn 7.11 of EC2 for calculating crack width

In EC2 clause 7.3.4(3), cover c is defined as the cover to longitudinal reinforcement. Say for a beam with cnom of 40mm and outer links of 16mm, the cover to longitudinal reinforcement will be 56mm. ...
3
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1answer
7k views

What is the effective depth of a beam with two layers of tension reinforcement?

In EC2 for calculating crack width and deflection, does the effective depth d refers to the depth from compression face to centroid of the tension reinforcement or is that calculated to the centroid ...
3
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1answer
226 views

What do the parameters k1 and k4 adopted in crack control tables in EC2 refer to?

Referring to page 123 of the code in EC2, BS EN 1992-1-1:2004, note 1 above Table 7.3N indicates that maximum bar spacing for crack control is derived based on $k_1$ parameter being 0.8 and $k_4$ ...
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2answers
258 views

What's the name and purpose of this specific shape of hollows in a reinforced concrete slab?

Below is a stack of reinforced concrete slabs with hollows (camera is positioned along the hollows' axis). Such slabs are used for floors - you build walls of the next floor, then lay such slabs such ...
2
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1answer
2k views

Reinforcing beam and slab with correct steel bar structure

This question might look silly. I am not knowing the correct engineering terms to use in this question. I am trying to explain using the words what I know in English. We have been hired some ...
3
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3answers
6k views

Can steel be replaced with aluminum alloy in reinforced concrete?

Can aluminum alloy be an alternative to steel for reinforcement in terms of the same forces encountered by reinforced concrete beams? Will it be economical and feasible? Are there organizations who ...
5
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1answer
4k views

Which one is preferable? Multiple layers of reinforcements or one layer of reinforcement?

For RC beams, which one is preferable to be designed for construction? Is it multiple layer of reinforcements or one single layer? and why? Eg. If the beam required 3T20, is it preferable one layer ...
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7answers
15k views

Why do we use multiple reinforcing bars instead of one bar with a big diameter in reinforced concrete?

Why do we use multiple reinforcing bars instead of one with a big diameter in reinforced concrete? Does increasing the number of reinforcing bars means that the reinforced concrete will have a higher ...