VIDEO
HIGHLIGHT
Log InSign up
Pórticos Traslacionales e Intraslacionales | 2/30 | UPV
SummaryTranscriptChat

Pórticos Traslacionales e Intraslacionales | 2/30 | UPV

Introduction to Sway and Non-Sway Steel Frames

In this section, Arianna Guardiola introduces the concept of sway and non-sway steel frames. She explains the definitions of these frames and how to classify a given steel frame into sway or non-sway.

Definition of Non-Sway Frame

  • Non-sway steel frames are those in which the internal forces caused by deformation can be neglected.
  • If the horizontal displacement is generated by horizontal loads and does not significantly increase the internal forces at the base of the columns, it can be considered a non-sway frame.

Definition of Sway Frame

  • Sway frames are those in which displacements have a substantial influence on the internal forces.
  • When the displacement is large enough to generate additional internal forces in the deformed structure that cannot be neglected, it is classified as a sway frame.

Classification of Steel Frames

  • To classify a plane steel frame as sway or non-sway, an initial elastic linear global analysis is performed.
  • The coefficient "r" is calculated for each storey and combination of load.
  • "r" represents the ratio between total vertical reaction at the base of each storey and total horizontal reaction on that storey's basis.
  • If "r" is greater than 0.1, it indicates a sway frame.

Braced Frames

  • A braced frame has sufficient stiffness in its bracing system to resist all horizontal loads.
  • The code defines a braced frame as one where the bracing system reduces horizontal displacements by at least 80% compared to an unbraced frame.

Design Considerations

  • To reduce relative horizontal displacement and classify a steel frame as non-sway, columns may need to be redesigned until "r" is less than or equal to 0.1.
  • When a steel frame is considered a braced frame, it is assumed that all horizontal actions will be resisted by the bracing system.

Conclusion

In this section, Arianna Guardiola concludes the discussion on sway and non-sway steel frames and highlights the importance of considering second-order effects and designing bracing systems for resisting horizontal forces.

Summary

  • Non-sway frames can neglect internal forces caused by deformation, while sway frames have significant displacements influencing internal forces.
  • Steel frames are classified based on the coefficient "r" obtained from an initial analysis.
  • Braced frames have a bracing system that reduces horizontal displacements by at least 80% compared to unbraced frames.
  • Design considerations involve reducing relative horizontal displacement and ensuring sufficient stiffness in the bracing system to resist all horizontal loads.

New Section

This section discusses the classification of braced frames as sway or non-sway, based on the bracing system and coefficient r.

Braced Frame Classification

  • A braced frame can be considered a non-sway frame .
  • The bracing system may be sway or non-sway .
  • To classify the bracing system, we need to consider all horizontal and vertical loads .
  • If the coefficient r is less than or equal to 0.1, the frame is non-sway .
  • If the coefficient r is greater than 0.1, further classification is required .

New Section

This section highlights important points related to performing a global analysis of a structure.

Global Analysis of Structures

  • Performing a global analysis involves calculating reactions, internal forces, moments, and deflections for the undeformed structure .
  • When using equations from tables, manuals, or commercial software for structural analysis, it is necessary to classify the frame as non-sway .
  • A steel frame is classified as non-sway if the coefficient r is less than 0.1 for all combinations of loads and storeys .

New Section

This section explains how a braced frame can be classified as non-sway based on its ability to reduce horizontal displacements.

Braced Frame Classification - Horizontal Displacements

  • A braced frame that reduces at least 80% of horizontal displacements can be classified as non-sway .
  • The responsibility of resisting all horizontal loads lies with the bracing system .
  • The bracing system can be sway or non-sway and needs to be classified accordingly .

New Section

This section provides bibliographic recommendations for further information on the subject.

Bibliographic Recommendations

  • For more information on the topics discussed, refer to relevant literature .

Timestamps are provided in seconds.

Video description

Título: Pórticos Traslacionales e Intraslacionales Descripción: Se definen los conceptos de traslacionalidad e intraslacionalidad según los criterios del Código Técnico de la Edificación. Se completa con la definición de pórtico arriostrado. Guardiola Víllora, AP. (2011). Pórticos Traslacionales e Intraslacionales. http://hdl.handle.net/10251/13194 Descripción automática: En este video, la profesora de Estructuras Metálicas en la Escuela de Arquitectura explica los conceptos de pórticos traslacionales e intraslacionales, así como el pórtico arriostrado, utilizando el Documento Básico de Seguridad Estructural, Acero, del Código Técnico. Un pórtico intraslacional es aquel donde los efectos de segundo orden, surgidos por deformaciones estructurales, son despreciables y no afectan significativamente las solicitaciones. Se pueden aplicar ecuaciones de equilibrio a la estructura sin deformar. En cambio, los pórticos traslacionales exhiben desplazamientos que influyen sustancialmente en los esfuerzos de la estructura, requiriendo métodos de cálculo no lineales que consideren estos efectos. Para determinar la traslacionalidad de los pórticos, se calcula el coeficiente 'r', basado en las reacciones verticales y horizontales, así como el desplazamiento horizontal relativo entre plantas y la altura correspondiente. Si 'r' es mayor que 0.1, el pórtico es traslacional. Para lograr un comportamiento intraslacional, es necesario reducir el desplazamiento horizontal relativo, ajustando las dimensiones de los soportes hasta que 'r' sea menor o igual a 0.1. Un pórtico arriostrado, por su parte, contiene elementos como las cruces de San Andrés que proporcionan rigidez contra cargas horizontales. La norma define que estos deben reducir los desplazamientos horizontales en al menos el 80% en comparación con la estructura sin arriostrar. Si se cumple esta condición, el pórtico con arriostramiento puede considerarse intraslacional. Finalmente, se establece que para realizar un análisis elástico es necesario que el pórtico sea intraslacional, con un coeficiente 'r' inferior a 0.1 en todas las cargas y plantas. El pórtico arriostrado asumirá las cargas verticales, y el sistema de arriostramiento, las cargas horizontales. El video concluye con recomendaciones bibliográficas para profundizar en el tema. Autor/a: Guardiola Villora Arianna Paola Curso: Este vídeo es el 2/30 del curso Curso Estructuras de Acero en Edificación | Universitat Politècnica de València (UPV). https://www.youtube.com/playlist?list=PL6kQim6ljTJtbUixDg4BF9uu-xpjVY4GN + Universitat Politècnica de València UPV: https://www.upv.es + Más vídeos en: https://www.youtube.com/valenciaupv + Accede a nuestros MOOC: https://upvx.es #Arriostramientos #Pórticos #Estructuras de acero #Intraslacional #Traslacional #MECANICA DE LOS MEDIOS CONTINUOS Y TEORIA DE ESTRUCTURAS