Summary of "Screen recording 2025 07 19 3 01 57 PM"

The video is a detailed technical webinar focused primarily on the design of buildings for wind effects and earthquake-resistant capacity design, featuring two main expert presentations followed by a Q&A session and concluding remarks.

Part 1: Wind Effects on Tall Buildings (Presented by Dr. Lakshmi)

Overview: The session dives deep into how wind interacts with tall and super-tall buildings, focusing on structural classification, dynamic wind effects, and design criteria based on Indian Standards (IS-875 Part 3 and IS-16700).
Key Concepts Covered:
- Classification of buildings by height and dynamic behavior under wind (rigid, dynamic, fluid-structure interaction).
- Wind forces: along-wind (drag), across-wind (lift), and torsional moments due to asymmetric pressure distribution.
- Phenomena such as buffeting, vortex shedding, vortex-induced vibrations, and aerodynamic instabilities like flutter and galloping (more critical for bridges than buildings).
- Importance of frequency (especially below 1 Hz) and damping in dynamic wind response.
- Gust factor method (introduced by Prof. AG Davenport) for calculating peak wind loads.
- Aerodynamic interference effects in clustered buildings and how spacing influences wind loads—shielding or adverse effects.
- Wind tunnel testing (rigid, pressure integration, aeroelastic models) and computational fluid dynamics (CFD), especially Large Eddy Simulation (LES) as a modern approach to simulate dynamic wind behavior.
- Aerodynamic modifications to reduce wind forces: tapering, setbacks, chamfered corners, openings, twisting shapes, and spoilers.
- Structural modifications including tuned mass dampers (TMDs) and tuned liquid dampers (TLDs) for vibration control.
- Serviceability and user comfort criteria based on acceleration limits for residential and commercial buildings.
- Code provisions for tall buildings over 150m, including site-specific wind tunnel studies, instrumentation, and minimum design loads.
Notable Highlights:
- Examples of iconic tall buildings like Burj Khalifa and Taipei 101 illustrating aerodynamic design.
- Emphasis on preparing databases of building shapes and dynamic properties to improve code provisions.
- Practical advice on when to carry out wind tunnel studies and how to interpret results.
Q&A Highlights:
- Wind design for footbridges and human-induced vibrations.
- Differences in damping definitions for wind vs. earthquake loads.
- When to apply gust factors and combined along-wind and across-wind loads.
- Handling future development in wind interference calculations.
- Use of pressure vs. force coefficients depending on building height.
- Guidance on modeling tuned mass dampers in analysis.
- Availability of wind tunnel facilities in India for research and commercial purposes.
- Explanation of wind directionality considerations in codes.

Part 2: Earthquake Capacity Design of Tall Buildings (Presented by Dr. Yogindra Singh)

Focus: Capacity design principles emphasizing ductile failure modes in RCC structures, particularly for earthquake resistance.
Core Ideas:
- Avoid brittle failure modes (shear failure, beam-column joints, slab punching) and promote ductile flexural failure.
- Analogy of a chain with ductile and brittle links to explain capacity design—make brittle links stronger than ductile ones to ensure ductile failure.
- Strong column–weak beam philosophy: columns must be stronger than beams by a factor of 1.4 (accounting for overstrength and strain hardening).
- Differentiation between columns, beams, and shear walls based on bending moment curvature (single vs. double curvature).
- Detailed discussion on shear wall design:
  - Confinement reinforcement in boundary elements.
  - Minimum thickness requirements and prevention of out-of-plane buckling.
  - Anchorage and detailing of horizontal reinforcement.
  - Overstrength factors for shear walls and columns (up to 3 for slender shear walls).
  - Mode shape changes after hinge formation and resulting amplification of shear forces.
  - Coupled shear walls and the role of coupling beams, including special detailing for diagonal reinforcement to resist large shear forces.
  - Use of steel or composite coupling beams for enhanced ductility.
  - Importance of confining reinforcement continuity and anchorage for steel elements embedded in concrete.
- Discussion on construction joints, reinforcement detailing, and addressing complex structural configurations like floating columns.
Q&A Highlights:
- Clarifications on code provisions for foundation embedment, overstrength factors, reinforcement detailing, and drift limits.
- Differences and harmonization between Indian codes and international codes (ACI, Eurocode).
- Practical challenges in implementing new code provisions.
- Use of composite and metallic coupling beams.
- Handling openings in shear walls and edge pier reinforcement.
- Importance of faithful modeling in structural analysis software.

Closing Remarks and Vote of Thanks

Delivered by Mr. Ravindra Desh Pande, who acknowledged the speakers and participants, highlighted the importance of integrating wind and seismic design considerations for strength,