The new ACI 318-19 shear equations: main changes and a feasible mechanical interpretation.

The American Concrete Institute (ACI) has just launched the new code ACI 318-19 with a new equation for the concrete contribution to the shear strength. This video comments the most important changes and presents a possible mechanical interpretation to this new equation. This interpretation is not exclusive and this video does not represent the official ACI point of view.
A new paper published ACI Structural Journal explains the development of this new equation:
Kuchma, D. A., Wei, S., Sanders, D. H., Belarbi, A., & Novak, L. C. (2019). Development of the One-Way Shear Design Provisions of ACI 318-19 for Reinforced Concrete. ACI Structural Journal, 116(4). Link to International Concrete Abstracts Portal: www.concrete.org/publications...
The mechanical interpretation given in the second part of the video is based on the Compression Chord Capacity Model (CCCM). More information regarding this model can be found at the following references:
Marí, A., Bairán, J., Cladera, A., Oller, E., & Ribas, C. (2015). Shear-flexural strength mechanical model for the design and assessment of reinforced concrete beams. Structure and Infrastructure Engineering, 11(11), 1399-1419. Available at: doi.org/10.1080/15732479.2014...
Cladera, A., Marí, A., Bairán, J. M., Ribas, C., Oller, E., & Duarte, N. (2016). The compression chord capacity model for the shear design and assessment of reinforced and prestressed concrete beams. Structural concrete, 17(6), 1017-1032. Available at: doi.org/10.1002/suco.201500214
Cladera, A., Marí, A., Bairán, J. M., Oller, E., & Ribas, C. (2017). One-way shear design method based on a multi-action model. Concrete International, 39(9), 40-46. Available at: www.concrete.org/publications...
The Compression Chord Capacity Model has been developed by researches from the Technical University of Cataluña (UPC) and the University of the Balearic Islands:
Antonio Marí (UPC)
Antoni Cladera (UIB) - Twitter: @ToniCladera3
Jesús Miguel Bairán (UPC)
Carlos Ribas (UIB)
Eva Oller (UPC)
Noemí Duarte (UPC)
Video recorded by: Servei de Recursos Audiovisuals (UIB)
Edition: Imalay Vilar (UIB)

[@djivaha]

Thank you for the video! Just saw your channel and a lot of valuable resources - congratulations on the work!

[@thebarbarian493]

thank you very much for kind and valuable efforts _ respects from Turkey

[@sarmedwahab7288]

Thanks Professor for an interesting, engaging and informative lecture.

[@victorarmandoportillayupan1681]

Thank you so much for this video, your explanation is clear and the use of the blackboard is awesome! Congratulations, regards from Perú.

[@ConStructUIB]

Thanks for your kind comment!!!!!

[@multicolor10]

Interesante video colega! Si le interesan las estructuras de concreto y su diseño según aci u otros, le pasó un link nuevo conucho material, saludos! ruclips.net/video/DlBzPnrFa7U/видео.html

[@mr.kpadmanadham550]

Very good appreciated your recent updation on size effect against shear.

[@victoraguilar3167]

Super buen video, profesor Cladera! Gracias.
Su modelo me da mejores resultados cuando uso la corrección por d anterior a ACI 446.

[@multicolor10]

Buen video! Para mis colegas, si les interesa el diseño en concreto, se creo un canal en habla hispana con mucho material de un profesor de concreto armado, dejo link, saludis, ruclips.net/video/DlBzPnrFa7U/видео.html

[@amrabdullah1995]

Thank you professor for this useful video

[@jafarahmedyousif5851]

Thank you so match for this video

[@AbdallaTalaat]

Thank you very much for this video!

[@ConStructUIB]

Thanks!

[@jr3474]

Muchas gracias por la explicación. Suscrito!

[@juanvladimirvillagrasoto9286]

Buen vídeo. Gracias

[@structuralengineeronline]

Excellent👍

[@fer12mar12]

Muy agradecido por la explicación

[@multicolor10]

Buen video! Si le interesa el diseño en concreto armado se creo un nuevo canal con mucho material interesante, de un profesor de concreto armado en habla hispana, saludis, ruclips.net/video/DlBzPnrFa7U/видео.html

[@ahmadzamanifar4987]

thank you very much +++++ very useful

[@abdulsaboorsakhizada8974]

Thanks for your informative video. Could you please explain the MCFT method and why there is a huge difference in the calculation of the coefficients between the ACI formulas and those of the MCFT method. I would greatly appreciate it. Thanks!

[@PokeYourEyez]

Whatever he is using to write on, I want it.

[@cesaralexisbenitesjimenez1402]

¿Qué programa utilizan para escribir así? ¡Es asombroso!

[@ConStructUIB]

No hay software mágico, es una pizarra de cristal y software solo para invertir la imagen. ;-)

[@JuanCarlos-gs1nm]

Me podrían aclarar porque el ACI 318-19 permite usar cualquiera de las dos ecuaciones a) o b) de la tabla 22.5.5.1 para el caso en que Av>Avmin, si la diferencia entre una y otra en algunos casos podría ser casi del doble.

[@ConStructUIB]

Para el caso de elementos sin armadura a cortante, no hay duda: el efecto tamaño es de gran importancia, y se debe calcular con la fórmula que incluye el factor "gamma_s" (fórmula c).
En el caso de elementos con armadura a cortante superior a la armadura mínima, se permite utilizar tanto las fórmulas a) o b), ninguna de las dos incluye el efecto tamaño (tiene mucha menor importancia este efecto al disponer de armadura a cortante), pero la ecuación b) incluye el factor de la cuantía de armadura longitudinal, que no está incluido en a). En estos casos te recomendaría considerar el máximo de ambos valores, que generalmente será el dado por la fórmula a). El hecho de que se incluyan ambas fórmulas creo que viene por tradición, ya que en la normativa ACI318, desde hace años, incluye la fórmula simplificada (fórmula a), y otra más refinada (que ha cambiado un poco). En todo caso, en mi opinión, se puede utilizar la fórmula a) en el caso de elementos con armadura a cortante sin ningún problema (ahorra trabajo y te dará, en general, mayores resistencias). En caso de tener un excel, implementa que tome el máximo de ambos valores....

[@JuanCarlos-gs1nm]

@@ConStructUIB Gracias por su respuesta y la recomendación.

[@hjnery]

Could you make the article quoted please?

[@ConStructUIB]

Thanks for your comment. Prof. Cladera basically quotes two papers during this video:
Kuchma, D. A., Wei, S., Sanders, D. H., Belarbi, A., & Novak, L. C. (2019). Development of the One-Way Shear Design Provisions of ACI 318-19 for Reinforced Concrete. ACI Structural Journal, 116(4). Link to International Concrete Abstracts Portal: www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&ID=51716739
Cladera, A., Marí, A., Bairán, J. M., Oller, E., & Ribas, C. (2017). One-way shear design method based on a multi-action model. Concrete International, 39(9), 40-46. Available at: www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&ID=51701013
The access depends on ACI membership....

[@mr.d3916]

Why it is permissible to
neglect size effect factor when you use it in the analysis and design of foundation as stated in section 13.2.6.2 of ACI 318-19?

[@ConStructUIB]

This is, indeed, a good question, but I've no idea!! I don't know any technical justification...

[@mr.d3916]

At first, I thought foundations are included in this size effect factor. I am quite surprised because this will hugely impact those already build structures with large footing thickness. But after reading this ACI section, again I was confused because footings are also slabs typically without shear reinforcement, so what is the reason about this exemption? I also noticed that the code did not state any commentary about this section. Hopefully the next edition will explain this. Thanks.

[@shafaat786]

@@ConStructUIB
Thanks Sir for excellent presentation...
I have one building designed by designer in 2018 but now in 2022 they want tonconstruct..Now Contractor checked and found that based on ACI 318 19 punching shear exceed value more that 1 in SAFE design ...There is confusion to consider this updates and revis foundation or keep it as per ACI318 14...please advise..

[@shafaat786]

For Raft foundation only..

[@ConStructUIB]

Thanks for your comment, but I'm afraid I do not understand it quite enough to be able to advise anything... sorry for that. I guess that, depending on the State, you'll have adapt it to ACI 318 19 and, the shear strength for a raft foundation (usually without shear reinforcement) should be, I think, lower for the new provisions than for the ACI318-14...

[@juanpablodezamartell2588]

Por favor en español lo pueden grabar también

[@ConStructUIB]

Casi todo el contenido del canal está en español, pero este vídeo se enfocó en inglés y no disponemos de él en otro idioma... ahora mismo nos resulta imposible volverlo a grabar, lo sentimos

[@jafarahmedyousif5851]

Thank you very match for this video