Summary of "Screen recording 2025 07 19 9 55 20 AM"

Summary of YouTube Video Subtitles: "Screen recording 2025 07 19 9 55 20 AM"

Overview

This video is a detailed webinar (Webinar #149) hosted by Epicon's Friends of Concrete (EFC), focusing on the design of tall buildings for wind and seismic forces. The webinar is structured as a knowledge-sharing platform for structural engineers, architects, researchers, and students, with a strong emphasis on technical education, code provisions, and practical applications in civil and structural engineering.

Key Technological Concepts and Product Features Discussed

1. Wind Effects on Tall Buildings

Wind Climate and Characteristics
- Wind varies with terrain, topography, and height (parabolic variation).
- Wind speed affected by atmospheric pressure differentials and earth’s rotation (Coriolis effect).
- India’s wind climate is unique due to monsoons, tropical cyclones, thunderstorms, and tornadoes.
- Cyclonic storms and their formation, wind speed zones, and impact on coastal regions discussed in detail.
- Wind speed maps and zones based on Indian Meteorological Department (IMD) data.
- IS-875 Part 3 (2015) code provisions for wind loads, including terrain categories (TC1 to TC4), topography factors, and cyclone importance factors (K1 to K4).
- Boundary layer wind flow explained using logarithmic and power law profiles.
- Turbulence intensity and energy content in wind described, including macro- and micro-meteorological peaks.
- Wind pressure coefficients for building components (roof, walls, openings) and overall force coefficients for buildings.
- Effect of building geometry (roof shape, openings) on wind loads and uplift forces.
- Differences between uniform flow and boundary layer flow on pressure distribution.
- Practical design considerations including wind directionality factor, area averaging factor, and combination factors.
Practical Applications and Case Studies
- Design of low-rise and tall buildings for wind forces.
- Importance of aerodynamic modifications and wind tunnel testing.
- Use of IS-875 provisions for calculating design wind pressures and forces.

2. Seismic (Earthquake) Forces on Tall Buildings

Comparison of Wind and Earthquake Forces
- Earthquake forces are generally larger but rarer; wind forces are more frequent and govern design for tall buildings due to dynamic effects.
- Earthquake acceleration varies about zero (no mean), wind varies about a mean velocity.
- Earthquake design considers longer return periods (2,500 to 10,000 years) compared to wind (typically 50 years).
- Earthquake design accepts damage (inelastic behavior), wind design aims for elastic behavior.
Seismic Hazard and Ground Motion Characteristics
- Parameters: amplitude, frequency content, and duration of shaking.
- Source, path, and site effects influence ground motion characteristics.
- Response spectrum concept explained for single degree of freedom (SDOF) systems; fundamental and higher modes considered.
- Local soil amplification effects illustrated by Mexico City earthquake example.
- Revised IS 1893 code changes including spectral shape up to 10 seconds, velocity and displacement control ranges.
- Importance of vertical ground motion and damping factors in design.
- Site classification based on shear wave velocity (A to E classes).
- Load factors and importance factors for different structure categories (normal, important, critical, special).
- Design basis earthquake (DBE) and maximum considered earthquake (MCE) concepts clarified.
- Probabilistic vs deterministic seismic hazard assessments explained.
Design and Analysis Methods
- Response spectrum method and time history analysis (linear and nonlinear).
- Selection and scaling of ground motion records for time history analysis.
- Use of software tools for spectral matching (e.g., SizeMatch, WaveManager).
- Consideration of ductile detailing even if wind governs design, due to possible larger earthquakes.
- Practical issues in modeling complex buildings with podiums and towers.
Non-structural Components
- Amplification of floor accelerations and design criteria for architectural/non-structural elements.

Additional Highlights

Epicon’s Background
- Epicon Consultants Pvt Ltd is an ISO 9001:2015 certified company with a long history of workshops and webinars since 1999.
- EFC has conducted 86 workshops and 48 webinars in recent years.
- The webinar series targets practicing engineers, architects, government bodies, and students.
Webinar Format
- Two main sessions, each with a 90-minute presentation followed by Q&A.
- Recordings and certificates of participation provided.
Q&A Highlights
- Clar