Questions tagged [reinforced-concrete]

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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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1answer
32 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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3answers
52 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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1answer
52 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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3answers
64 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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2answers
111 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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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
46 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 ...
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0answers
68 views

primary column vs secondary column

all. I am not sure what is primary column and secondary column. My initial guess is this: The primary column is joined by primary beam, while the secondary column is joined by secondary beam. How ...
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1answer
40 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.
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3answers
80 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
65 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 ...
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0answers
92 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 ...
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1answer
116 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 (...
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1answer
18 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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2answers
138 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
47 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
18 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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0answers
50 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. ...
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1answer
59 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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1answer
3k 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 ...
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1answer
84 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
177 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 ...
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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 ...
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1answer
2k 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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1answer
433 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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1answer
603 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 ...
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1answer
8k 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? ...
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3answers
4k 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 ...
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3answers
4k views

Reasons for bending direction of rebars in beams

When we do detailing for RC structures, the rebars in a beam have to anchor into a column. For an external column (not at the roof), the rebars are usually bent in 90 deg to provide sufficient ...
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0answers
285 views

How would I model a load bearing brick wall supported on a beam in FEM

I have a continuous beam supported on columns. I need the brickwork above to act as load bearing wall for the next floor above. How would I model this in a FEM suite like SUMO (Prokon) ? In SUMO I ...
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1answer
319 views

Shear strength of reinforced concrete filled PVC pipe

BACKGROUND: I'm burying a 3 foot x 4 foot drainage box (2 foot tall) in my driveway to hold/distribute excess gutter flow (1" of rain produces ~21cuft). I've constructed the walls with brick, laid on ...
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2answers
254 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 ...
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2answers
762 views

Reinforced concrete design: will there be extra nominal moment on column in a frame structure?

Say I have a simple reinforced concrete frame (3as shown below) with all beam ends pinned: ( the keyplan) This is the detailing output: The beam elevation detail ( left), beam cross section detail ...
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1answer
216 views

do prestressing tendons located in the compression zone contribute to compression reinforcement?

when doing the normal RC design of an RC beam, it is determined that compression steel reinforcement is required, does a prestressed tendon in the compression zone contribute to the area of ...
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1answer
5k 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. ...
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3answers
447 views

Why would a column expand before accepting load through a narrow thunk?

Here's a column top which holds a driveway overbridge. The column is a reinforced concrete cylinder with an inverse truncated cone on top - so it expands sideways at its top. The column top holds ...
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1answer
432 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 ...
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1answer
337 views

Basic Hook development length using CSA A23.3 provisions

I have 8" thick reinforced concrete walls and I would like to anchor my horizontal corner reinforcement with only 1 hook (I have only 1 layer of reinforcement in both walls). The problem is CSA A23.3 (...
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3answers
3k views

What are safe locations for openings in reinforced concrete beams?

I had an argument with a friend about the safe location for openings in reinforced concrete beams. I've chosen position 1, a little above reinforcement steel, as at this location, the beam is ...
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2answers
1k views

Connections between RC retaining walls and sheet pile retaining walls

I'm working on a flood defence scheme in which a section of RC flood wall becomes sheet piles. The reasons for this aren't important, but the solution isn't to simply make all walls one or the other. ...
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7answers
13k 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 ...
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1answer
85 views

How monolitic is concrete when falsework is being crafted for parts of future structure only?

Suppose we craft a reinforced concrete pylon for a cable-stayed bridge. It's very tall and rather thin. No one builds falsework for the entire pylon - it'd be very impractical. Instead, a part of ...
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1answer
577 views

Multi-stage/multi-section reinforced concrete slab design

In pre-cast bridges, one often lays beams over the columns and then places thin pre-cast "pre-slabs" over the transversal spans between the beams. These slabs already contain all the requisite ...
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2answers
2k views

Material Properties: Does bending reduce iron rebar's strength?

I'm reading an introduction to structural engineering book and there's a fundamental concept I'm trying to relate to real life: In construction, we regularly bend iron rebar into a variety of shapes ...
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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 ...
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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 ...
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3answers
4k views

Why design a cable stayed bridge with pylons inclined towards the obstacle being spanned?

Here's a YouTube video with a concept of a bridge which is currently under construction in Saint Petersburg. The bridge largest span is cable stayed and designed to drive traffic over the Neva river ...
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1answer
1k views

Reinforced Concrete Columns - Interaction Diagram Question

I'm confused about some concepts concerning interaction diagrams for reinforced concrete columns. Hopefully somebody will be able to answer these: Point with zero tensile strain, but before uniform ...
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1answer
308 views

Telehandler wall collision forces

The following scenario: I am tasked to design a 6.6m high reinforced concrete wall in an industrial building. We have a 10 ton Telehandler (telescopic loader) with 7m maximum reach, loading 1500kg ...