The Burj Khalifa in Dubai, completed in 2010, is currently the world's tallest building. What is its height?

541 m 632 m 828 m 1,000 m

For a very tall building on soft clay soil in a coastal city, which foundation type would an engineer most likely recommend?

Shallow strip footings just below ground level Deep pile foundations driven through the soft clay to reach a bearing layer of rock or firm soil A small concrete pad directly under the building's central column No foundation is needed if the building is tall enough to be self-supporting

A 200 m office tower in a windy city sways 300 mm at the top in a severe storm. Engineers are asked to reduce this motion to improve occupant comfort. What is the most effective structural solution?

Adding more floors to increase the building's weight Painting the outer surface with a friction-reducing coating Installing a tuned mass damper (TMD) — a large mass on springs or a pendulum that vibrates out of phase with the building to cancel sway Removing the top floors to lower the centre of mass

Taipei 101 in Taiwan is fitted with a famous tuned mass damper visible to visitors inside the building. How heavy is this damper, and what is it made of?

100 tonnes; it is a concrete block on rubber bearings 660 tonnes; it is a solid steel sphere suspended as a pendulum between floors 87 and 92 2,000 tonnes; it is a water tank on the roof 50 tonnes; it is a lead weight mounted on hydraulic actuators

What is base isolation in earthquake engineering, and which countries use it most widely?

Digging a deep basement to separate the building from surface shaking; used mainly in the USA The building sits on rubber-and-steel laminated bearings that absorb horizontal ground movement, preventing the full earthquake motion from reaching the structure; widely used in Japan and New Zealand Filling the ground with concrete to stop it from shaking during an earthquake Constructing buildings on stilts so they float above earthquake waves; used in coastal cities

What is a shear wall in a tall building, and what forces does it primarily resist?

A glass curtain wall that reduces wind pressure on the building's facade A reinforced concrete or steel-braced wall that is very stiff in its own plane, resisting lateral forces from wind and earthquakes that would otherwise cause the floors to rack sideways A decorative exterior wall panel with no structural function A foundation wall that prevents soil from entering the basement

In many skyscrapers, outrigger trusses connect the central concrete core to the perimeter columns at plant-room levels every 15–20 floors. What is the structural purpose of outriggers?

They support the weight of the mechanical plant equipment housed at those levels They engage the perimeter columns in resisting the overturning moment caused by wind and seismic loads, dramatically increasing the building's lateral stiffness without adding much concrete to the core They prevent the building from floating upward in a flood They transfer roof loads directly to the foundations, bypassing the columns

Why is ductile design critical for buildings in seismic zones?

Ductile materials are lighter, reducing the total seismic force on the building Ductile design ensures that the building never moves during an earthquake Ductile materials like reinforced concrete and steel can absorb seismic energy by deforming plastically without sudden fracture, giving occupants time to evacuate before collapse Ductile structures are cheaper to build and need no seismic design at all

What is a 'soft storey' in a building, and why does it make earthquake damage worse?

A floor with very thick reinforced concrete, which is too heavy and crushes lower floors A floor that is much weaker or more flexible than the floors above (e.g. an open ground floor for car parking); it concentrates all the seismic deformation and collapses while upper floors drop onto it The top floor of a skyscraper, which sways the most in wind and earthquake A basement level that is built below the water table and is prone to flooding

The Shanghai Tower, completed in 2015, is China's tallest building at 632 m. One of its key engineering features is a twisted exterior curtain wall. What is the aerodynamic benefit of this twist?

The twist increases wind loads to pre-stress the structure and make it stiffer The twist is purely aesthetic and has no aerodynamic function The twist reduces wind loads by about 24% compared to a conventional square tower by disrupting organised vortex shedding The twist allows rainwater to drain from the facade without needing downpipes

One World Trade Centre in New York, completed in 2014, has a height of 541 m to its architectural top. Why was this specific height chosen?

541 m is the maximum height permitted by New York City zoning regulations 541 m is exactly the height of the original Twin Towers combined 541 m equals 1,776 feet — a symbolic reference to the year the United States Declaration of Independence was signed 541 m was the maximum height achievable with the pile foundation depth available at that site

A hospital is being designed in a high-seismic zone. The structural engineer recommends base isolation rather than a conventional fixed-base design. What is the key advantage for a hospital specifically?

Base isolation is cheaper than conventional design for hospitals of any size Base isolation prevents the hospital from experiencing any vertical acceleration Base-isolated buildings never require maintenance after an earthquake A base-isolated hospital can remain fully operational during and after a major earthquake because equipment and contents are protected from damaging floor accelerations