A Deep Dive into Technical Solutions and Case Studies

Vitali Bebekh, Design Engineering Manager and Technical Lead, Meriton Group, Co-Author and Editor

William Zhang, Founding Director, Palantir Consulting, Co-Author and Editor

High-rise residential buildings stand as monumental achievements of modern engineering, blending technical precision, innovative design, and long-term sustainability. These structures face unique challenges—from lateral stability under extreme wind conditions to optimising basement designs in constrained urban spaces.

About the Editor

Vitali B. serves as the Design Engineering Manager and Technical Lead at Meriton Group in Sydney, New South Wales. In this capacity, he oversees the structural design and engineering of high-rise residential projects, ensuring that architectural vision aligns seamlessly with structural integrity and performance. His leadership has been instrumental in the successful execution of complex developments.

Beyond his role at Meriton, Vitali is recognised for his contributions to the engineering community. He has shared his expertise at industry conferences, including the T.H.T Summit held on November 6-7, 2024, at the Sydney Masonic Centre. At this event, he presented on "Overcoming Challenges of High-Rise Residential Construction in Queensland," offering insights into innovative solutions for structural and construction challenges in the region.

With a career dedicated to advancing structural engineering practices and promoting inclusive professional environments, Vitali Bebekh brings a wealth of knowledge and leadership to this publication as co-editor.

In this comprehensive article, we explore granular details of the architectural, structural, and engineering decisions that drive successful high-rise projects, supported by technical insights and detailed case studies from two super high-rise Tower developments referred to here as Project A and Project B (due to privacy reasons):

Project A - Tower 260m

Project A exemplifies the challenges and solutions in high-rise residential construction. With the North Tower reaching 79 floors (260m) and the South Tower at 53 floors (180m), these structures are feats of engineering ingenuity.

Project B - Tower 305m

Project B is a landmark development, with Tower 1 reaching 93 floors (305m) and Tower 2 at 79 floors (260m). These towers required innovative solutions to address their scale and environmental conditions.

1. Architectural Perspective: Form, Space, and Aerodynamics

1.1 Problem: Wind Pressures and Stability in Coastal Areas

Tall buildings in Queensland endure wind speeds of up to 58 m/s—70% higher than Sydney’s coastal conditions. This exposes them to significant lateral pressures, cross-wind accelerations, and resonance effects, all of which must be managed to ensure structural integrity and occupant comfort.

Solution: Aerodynamic Optimization

Design Decision: Both Project A and Project B underwent comprehensive wind tunnel testing with Windtech Consultants. This process refined their shape and orientation, balancing aerodynamic efficiency with aesthetic goals.

Project A

• Blow-through floors were strategically placed to reduce wind pressures by allowing air to pass through the structure.
• Tuned Sloshing Dampers (TSDs) were installed in the upper levels of the North Tower to reduce vibrations. These dampers were calibrated to counteract the building’s natural sway frequency of 7.7 seconds, dissipating energy caused by high winds.

Project B

• A core-and-outrigger spine wall system, supported by dumbbell mega-columns, provided lateral stiffness. This system ensured uniform load distribution and minimised deflections at upper levels.
• Collaboration with wind engineers refined building forms and dynamic properties, resulting in a natural frequency of 7.9 seconds for Tower 1, optimising stability without overdesigning.

1.2 Problem: Space Constraints in Dense Urban Sites

Excavating basements near tram lines or densely populated areas presents risks of ground movement, hydrostatic pressure, and limited access.

Solution: Integrated Basement Designs

Design Decision: For Project A’s four-level basement, a top-down construction method was selected. Here’s why:

• Mitigating Hydrostatic Pressure: Cut-off walls and dewatering systems controlled water ingress.
• Bracing Slabs and Buttress Piles: These elements increased lateral stability during excavation, ensuring minimal ground movement near tram lines.

Educational Note: Basement designs require collaboration between structural and geotechnical engineers to predict and counteract hydrostatic forces, particularly in areas with high water tables.

1.3 Problem: Maximising Usability of Podium Spaces

Podiums must house diverse functionalities—parking, retail, childcare—while supporting the structural weight of upper levels.

Solution: Multi-Use, Multi-Level Podiums

Design Decision: Project B’s podium incorporates eight levels, each optimised for specific functions. Parking levels are designed with post-tensioned slabs to maximise open space, while retail levels feature flexible column layouts for tenant adaptability.

• Sustainability Focus: Green spaces and natural ventilation are incorporated into podium designs to reduce operational energy consumption.

2. Structural Engineering Perspective: Ensuring Stability and Efficiency

2.1 Problem: Lateral Forces and Building Stability

Wind-induced lateral forces and seismic events pose significant risks to tall buildings. Traditional shear wall systems alone often lack the stiffness required for modern high-rises.

Solution: Core-and-Outrigger Systems

Design Decision: Both Project A and Project B leveraged a core-and-outrigger spine wall system, supported by mega-columns for additional lateral rigidity.

• Core Placement: Centrally located cores resist torsional forces, while outriggers distribute wind loads to exterior mega-columns.
• Outrigger Benefits: These systems limit deflection at upper levels, reducing stresses on secondary elements like fa?ades.

Technical Insight: The outrigger design increases the effective width of the lateral force-resisting system, enhancing stability without significantly increasing material costs.

2.2 Problem: Differential Shortening

Concrete creep and shrinkage can cause differential shortening between core walls and columns, leading to misalignment of structural and non-structural elements.

Solution: Predictive Models and Adjustments

Design Decision: Predictive models accounted for creep and shrinkage effects over a 10-year period. Adjustable connections were incorporated into fa?ade systems to accommodate movement.

• Material Selection: High-strength concrete with lower shrinkage rates was used for core walls to minimise differential movement.

Educational Note: These adjustments prevent cracking in cladding systems, maintaining aesthetic and functional integrity over decades.

2.3 Problem: Uneven Load Distribution

Tall buildings with varying floor areas or podium levels often experience non-uniform load distributions, complicating foundation design.

Solution: Layered Foundation Systems

Design Decision: Project B’s foundations combine raft slabs and king piles:

• Raft Slabs: Distribute loads evenly across weaker soil strata.
• King Piles: Extend into stable substrata, resisting both compression and tension forces from lateral loads.

Technical Insight: Piles were designed with diameters of 0.9m to 2.1m and lengths up to 50m, ensuring stability across varying soil conditions.

3. Fa?ade Engineering Perspective: Managing Environmental Pressures

Problem: Wind and Thermal Pressures

Dynamic wind loads, combined with thermal expansion, create stress concentrations in fa?ade systems, leading to potential failures.

Solution: Resilient and Flexible Fa?ades

Design Decision: Fa?ades were anchored using flexible connections to allow movement without damage. Cladding materials were tested for wind pressures exceeding code requirements.

Thermal Stack Effect Mitigation: Ventilated fa?ades reduced the build-up of internal pressures caused by rapid temperature changes.

Case Study Data: In Project A, intertenancy wall pressure studies revealed areas of heightened wind impact. Fa?ade designs were adjusted to withstand these localised pressures.

4. Remedial and Contractor Perspectives: Building for Longevity

4.1 Problem: Coastal Durability

Coastal environments accelerate material degradation due to saline exposure, threatening the long-term durability of structural and non-structural elements.

Solution: Enhanced Material Selection

Design Decision:

• Corrosion-resistant reinforcement bars and protective coatings were utilised for exposed structural elements.
• Waterproofing systems were integrated into hydrostatic tanked basements to prevent water ingress.

Key Measures:

• Hydrostatic Tanking: Waterproof membranes and drainage systems protected below-ground levels from water pressure.
• Protective Cladding: Salt-resistant fa?ade materials were applied to maintain aesthetics and functionality in saline conditions.

Technical Insight: These measures align with AS 3735 standards for durability in severe environmental exposures, extending the service life of the structure.

4.2 Problem: Tight Construction Timelines in Dense Urban Sites

Simultaneously managing basement excavation and superstructure construction in constrained spaces creates scheduling and logistical challenges.

Solution: Partial Top-Down Construction

Design Decision: For Project A - Tower 260m, top-down construction was selected to allow concurrent progress on the superstructure and basements.

• Permanent Bracing Slabs: Provided lateral stiffness during excavation, enabling safe continuation of basement work while minimising disruption to neighbouring infrastructure.
• Struts and Temporary Bracing: Supported the shoring system during deep excavations, ensuring stability.

Note: Top-down construction reduces overall project timelines by overlapping critical-path tasks, a necessity for high-value urban sites.

5. Property Owner Perspective: Enhancing Occupant Experience and Value

5.1 Problem: Occupant Comfort in High-Wind Zones

Wind-induced accelerations can make living in high-rise buildings uncomfortable, particularly at higher elevations.

Solution: Advanced Wind Mitigation

Design Decision: Tuned Sloshing Dampers (TSDs) were installed in Project A - Tower 260m, reducing wind-induced vibrations to below the thresholds specified by ISO 10137.

• TSD Design: Tanks were calibrated to counteract the building’s natural frequencies, dissipating energy effectively.
• Field Testing: Accelerometers measured vibrations, validating the effectiveness of damping systems during high-wind events.
• Occupant Feedback: Indicated a marked improvement in comfort, even during seasonal high winds, confirming the success of these mitigation systems.

5.2 Problem: Sustainability and Long-Term Efficiency

Property owners increasingly demand energy-efficient and sustainable building systems to reduce operational costs and environmental impact.

Solution: Biophilic and Energy-Efficient Designs

Design Decision: Podium spaces in both Project A - Tower 260m and Project B - Tower 305m were designed with green roofs and natural ventilation systems to improve energy efficiency.

• HVAC Optimization: Systems were integrated with energy recovery ventilators to reduce cooling loads.
• Green Spaces: Biophilic designs, such as rooftop gardens, improved thermal insulation and reduced heat island effects.

Note: These sustainability measures align with Green Star ratings, enhancing property value and tenant satisfaction.

6. Material Science Perspective: Innovations Supporting Structural Excellence

6.1 Problem: Challenges in Pile Construction

Drilling deep piles in high-pressure soils requires advanced materials and equipment to prevent collapse and ensure alignment.

Solution: Reinforced Piles and Innovative Splicing

Design Decision:

• King piles in Project B - Tower 305m used high-strength steel cages spliced with precision welding techniques to achieve the required depths without compromising integrity.
• Diameter Variability: Piles ranged from 0.9m to 2.1m in diameter, adapting to variable soil conditions and load requirements.
• Pressure-Resistant Concrete: Concrete mixes were designed to withstand hydrostatic pressures and chemical exposure.

Technical Insight: The use of advanced splicing techniques reduced on-site assembly times, improving efficiency and quality control.

7. Modular Construction Perspective: Accelerating Project Timelines

7.1 Problem: On-Site Labor and Quality Control

Traditional construction methods face challenges in maintaining consistency and meeting tight deadlines.

Solution: Prefabrication and Modularisation

Design Decision: For Project B - Tower 305m’s podiums, modular fa?ade panels and precast structural components were used.

• Prefabricated Fa?ade Systems: Panels were assembled off-site and installed with precision, reducing on-site labor demands.
• Precast Columns and Beams: Structural elements were prefabricated to exact specifications, ensuring uniform quality.

Case Study Data: Modular construction reduced Project B - Tower 305m’s overall timeline by 15%, significantly lowering labor costs and minimizing disruptions in a densely populated area.

8. Sustainability Perspective: Building for the Future

8.1 Problem: Energy Consumption in Tall Buildings

High-rise buildings often require significant energy inputs for HVAC systems, lighting, and vertical transportation.

Solution: Integrated Sustainability Features

Design Decision: Renewable energy sources, efficient mechanical systems, and water-saving technologies were incorporated into both Project A - Tower 260m and Project B - Tower 305m.

• Solar Panels: Installed on podium rooftops to offset energy consumption.
• Rainwater Harvesting: Systems collected and reused rainwater for landscaping and non-potable applications.
• Efficient Elevators: Regenerative braking systems captured energy during descent, feeding it back into the building’s power grid.

Educational Note: These sustainability strategies align with NABERS energy and water ratings, supporting regulatory compliance and enhancing long-term operational efficiency.

Closing Thoughts

Closing Thoughts High-rise residential construction is a testament to the harmony of art and science, where every design choice is a response to complex challenges. From mitigating wind-induced accelerations to crafting sustainable and community-oriented spaces, each decision reflects a balance between functionality, safety, and innovation.

Project A - Tower 260m and Project B - Tower 305m exemplify this ethos. By integrating advanced technologies such as Tuned Sloshing Dampers and predictive modeling for structural performance, these projects set new benchmarks for occupant comfort and long-term durability. Modular construction techniques and sustainability-focused designs further highlight how collaboration across disciplines can redefine urban living.

As we look to the future, high-rise developments must continue to embrace innovation, guided by a commitment to enhancing occupant experience and addressing environmental concerns. Whether it’s through advanced material science, cutting-edge wind engineering, or smarter construction methodologies, the skyscrapers of tomorrow will not only shape skylines but also improve the quality of life for their inhabitants.

With contributions from experts like Vitali Bebekh and informed by the latest research, the insights shared here aim to inspire engineers, architects, and developers to push boundaries and create structures that stand as enduring symbols of human ingenuity.

William Zhang

Technical Newsletter Edition

Palantir Consulting

Structural | Remedial | Peer Review | Facade

P.S. I have included this article in our AI Chatbot. Feel free to ask any questions about design and construction, instant access link here: https://www.palantirconsulting.com.au/chatmaster

Here is a compiled list of all citations referenced in the discussion for this article:

1. Tuned Mass Dampers and Wind-Induced Vibrations Research on TMDs reducing lateral displacements in structures by up to 84%. https://link.springer.com/article/10.1007/s41062-024-01511-8
2. Human Perception of Building Vibrations Insights into the psychological and physiological factors influencing occupant comfort. https://researchers.westernsydney.edu.au/en/publications/perception-of-vibration-and-occupant-comfort-in-wind-excited-tall
3. Wind-Induced Vibrations in High-Rises Studies on the use of accelerometers for assessing dynamic responses during high-wind events. https://link.springer.com/article/10.1007/s13349-022-00634-9
4. Structural Fatigue in Wind-Excited Structures Research on the impact of TMDs on wind turbine towers as analogous structures. https://link.springer.com/chapter/10.1007/978-3-319-08413-8_12
5. Dynamic Analysis of Tall Buildings Analysis of building dynamics under typhoon conditions to refine structural performance. https://link.springer.com/chapter/10.1007/978-4-431-54337-4_12
6. Conference Presentation by Vitali Bebekh Overview of Vitali’s contributions at the T.H.T Summit on overcoming high-rise construction challenges. https://ancr.com.au/wp-content/uploads/2024/10/THT-Summit-Brochure-3-Aimi.pdf
7. ISO 10137 Standards Guidelines for evaluating human exposure to vibrations in habitable buildings. https://www.iso.org/standard/40038.html