Seeking help regarding bending anchorage length in Eurocode2

[vvhighland]

Why there is no requirement such as ldh in ACI318 in Eurocode2. I can't find such provisions in Eurocode2. So when the straight anchorage length cannot be met, which point can be started to bend the rebar? Can we find some basis in Eurocode2 about this. Thank you!

 

[HTURKAK]

I am not sure i got your question. If this question is for standard bends , hooks , and loops pls look EN 1992
Figure 8.1: Methods of anchorage other than by a straight bar, in general. Ties and stirrups call for special shapes, as specified in EC2, 8.4 and 8.5.

lb,eq= 0.7 lb

I will suggest you also to look EN ISO 3766 (Construction drawings. Simplified representation of concrete reinforcement ) and next time , waiting more serious questions.
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He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[vvhighland]

Thank you for your help! Now I'm confused about the Figure 8.1. Is Lb,eq similar with ldh ? If the the lb,eq is too long so as the support is not wide enough, how can we design the rebar anchorage? The hook end can be lengthened ?

 

[HTURKAK]

- Lb,eq is similar with (0.75ldh )
- The minimum hook length is 5Ø. The minimum length of ( Lb,eq) will not change If you increase hook end length to 10 or 15 Ø,
- I do not know your specific problem and availability of headed deformed bars in your zone . You may consider the use of headed bars if could be an option.Pls look ACI 318 .
...

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[hardbutmild]

As HTURKAK mentioned, instead of 0,75 ldh, you'd use 0,7 ldh.
There is an option to decrease that value by increasing the tail length, but you need to check the stress inside the bend (usually you'd have to increase the mandrel diameter or add transverse reinforcement).
I hope you don't mind me asking a related question in the same topic, but does anyone know what about the anchorage of standard loops (U shape) where both legs are in tension? This would be the case of deep beams for example, I often find bars with horizontal loops at the end of the deep beam which means that both legs are in tension.
Because recently my national normative institution released a not yet finished version of a second generation of the Eurocode 2 and from that it seems that such loops can be considered anchored if concrete cover is not too small and mandrel diameter not too small.
Then I found this paper

https://www.pci.org/PCI_Docs/Public...Reinforcement in Precast Concrete Members.pdf

which seems to agree. It seems like this type of anchorage is extremely hard to pull out, especially if there is transverse pressure.
Then I took a look in the legendary book by Leonhardt (unfortunately I do not know german) and it is mentioned that this is very effective, but he never says what length of anchorage is sufficient, only that sometimes you need perpendicular bars to control splitting.
It is hard to anchor bars at the ends of deep beams and it would be very nice to know if something is anchored there.
Sorry again if I'm off topic, I can make a new thread if needed.

 

[HTURKAK]

Please find my understanding to ur questions ,

Pls look EN 1992 Figure 8.1 (d) equivalent anchorage length for standard loop,

Can you post a sketch , for this case ? The common detail is the use of separate bars with separate hooks .. the following figure is copy and paste from the book ( Vorlesungen über Massivbau DritterTeil Grundlagen zum Bewehren im Stahlbetonbau
by F. Leonhardt und E. Mönnig 1976 )

Pls look Figure Bild 4.16 Diagramm zur Bestimmung des erforderlichen Biegerollendurchmessers
min dB von Zugschlaufen mit Querbewehrung.

This book suggests the mandrel dia. dB with eq (4.6)

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He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[hardbutmild]

this is my example. I usually have one bar rather than two, why would I prefer two bars? Imagine needing 10 legs to transfer the tension, you'd need 10 bars, I'd need 5 and smaller height.

It's the same question as your picture... that is the book that I used. Look at that picutre, I have circled the problem... how long is a1 if db is achieved? Is it db/2 + 3*fi? This is not in the code and I don't really understand german, so I'm sorry if my questions look like they are answered in Leonhards text.

 

[HTURKAK]

I looked to the picture almost after 50 yrs again ,

- If the dia. dB is provided as per equation (4.6) you will use a2=a3= db/2 + 3*Φ ( pls look Tabel 7.2 )

- If the dia dB provided is less than equation (4.6), you will use a1= f*a*(1,1- dB/40de )

- This is in the code but in DIN 1045 ( this book ,by Leonhardt prepared as per DIN 1045 probably the same code also at kaiser Wilhelm era)
...

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[vvhighland]

Thank all experts above! Now I have a new question, in eurocodes or British codes, is the follow fig. right ? If there are some mistakes, why? Can you tell me which provisions in codes it cannot meet?

 

[HTURKAK]

Assuming negative moment develops at corner , the Fig. B the most reasonable but does not justify development length and mandrel dia.
Without knowing the moment dia. , column reinf. , seismicity it is hard to comment. I have copy and pasted the following fig. from the book (Bewehren nach DIN EN 1992-1-1 (EC2), by Klaus BEER) Reinf. no 1 could be a min. option.

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He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48