For Izmir’s Bayrakli and Karsiyaka waterfronts, how do high-rise sway/comfort standards and seismic isolation features differ in recent builds?

The short answer is that all recent high-rises in Bayrakli and Karsiyaka must comply with Turkey’s 2018 Earthquake Code, but Bayrakli’s newer commercial towers more often apply wind-tunnel–based sway/comfort criteria and performance-based analyses, while Karsiyaka’s mainly residential towers rely more on code-prescribed wind actions without seismic isolation unless a special design decision is made. The legal basis for seismic isolation is nationwide and optional unless specifically required by a project’s brief or building type, and occupant comfort under wind is handled through Turkish and international standards rather than a single local comfort limit.

Legal and technical framework that governs sway and isolation

Turkey’s Building Earthquake Code of 2018 (Türkiye Bina Deprem Yönetmeliği, TBDY-2018) applies to all buildings nationwide, including high-rises along Izmir’s Bayrakli and Karsiyaka waterfronts. The Code defines seismic hazard, analysis procedures, performance targets, drift checks, and a dedicated chapter for the design, qualification, and acceptance of seismically isolated buildings. It has been in force since 2019, following publication in the Official Gazette on 18 March 2018. Designers of recent towers in both districts must therefore demonstrate compliance with TBDY-2018 for strength and deformation under the relevant earthquake ground motions defined for the site class and importance category of the building. Seismic isolation, when used, must follow the Code’s special provisions covering isolator properties, testing, and system-level verification analyses. [1]

Alongside seismic rules, wind actions and serviceability checks that govern lateral sway and occupant comfort are taken from Turkish standards aligned with the Eurocodes and from international vibration comfort guidance. TS EN 1991-1-4, adopted by the Turkish Standards Institution, defines wind loads, terrain and roughness categories, coastal wind pressure parameters, and the methodology for dynamic response factors in tall, slender buildings—parameters that are directly relevant to waterfront towers exposed to sea breezes and storms. For occupant comfort thresholds, designers frequently reference ISO 10137, which sets recommended acceleration limits and evaluation methods for building vibrations perceptible to occupants; these criteria shape tuning of structural systems and supplemental damping where required. [2][3]

How practices differ between Bayrakli’s new city center towers and Karsiyaka’s residential waterfront

Bayrakli’s waterfront sits within Izmir’s “New City Center” planning area, where the municipality has concentrated high-rise commercial and mixed-use development since the late 2000s. In this zone, towers with large floorplates and greater heights have been permitted, which has pushed projects toward wind tunnel studies, refined dynamic analyses, and serviceability acceleration targets consistent with international practice. For such projects, wind loads from TS EN 1991-1-4 are calibrated with site-specific wind tunnel data, and comfort limits are checked against ISO 10137. This process leads to the frequent use of stiffening systems such as outriggers and belt trusses, and, where necessary, supplemental damping devices to keep peak accelerations within acceptable ranges for office and hotel occupancies. While the national code does not mandate wind tunnel testing, the combination of tower height, coastal exposure, and mixed-use occupancy in Bayrakli’s new city center has made these studies common practice to meet comfort criteria. [2][3][4]

Karsiyaka’s waterfront building stock developed under more residential-led zoning and, as a result, includes many mid-to-high-rise apartment buildings rather than supertall commercial towers. Recent residential projects in Karsiyaka are still subject to the same seismic analysis requirements of TBDY-2018 but commonly rely on code-based wind actions without commissioning project-specific wind tunnel tests. In this context, designers size lateral systems to meet serviceability criteria implied by the standard load combinations and check occupant comfort using ISO 10137 or similar guidance, typically without the need for specialized damping systems. The difference is not one of legal standards—those are identical citywide—but of project scale, occupancy, and the level of aerodynamic optimization warranted by the building height and use. [1][2][3]

Seismic isolation: what the code allows and what is used locally

TBDY-2018 provides a complete design framework for base-isolated buildings, including acceptance tests for isolators, modeling requirements, target performance levels, and checks under service and maximum considered earthquakes. Seismic isolation is not mandated for residential or office towers by the national code; instead, it is a design option that owners and engineers may adopt to reduce seismic demands and interstory drifts, provided they meet the code’s qualification and analysis provisions. In practice across Izmir, isolation has been widely implemented in critical facilities such as hospitals, where continuous operation after earthquakes is essential, and the design teams must comply with the code’s isolation chapter. Towers in Bayrakli’s commercial core and Karsiyaka’s residential strips have generally been designed as fixed-base systems using ductile lateral force-resisting frames, shear walls, and outrigger systems, meeting the code’s performance targets without base isolation. [1]

Local seismic demand context influences these choices. AFAD’s 2018 Turkey Earthquake Hazard Map shows significant hazard levels for the Izmir region, informing site-specific spectra used in TBDY-2018 analyses. After the 30 October 2020 Aegean (Izmir) earthquake, official post-event assessments highlighted concentration of damage in soft soil basins, particularly in parts of Bayrakli with unfavorable site conditions, underscoring the importance of rigorous site classification, geotechnical investigation, and drift control in design. While these findings strengthened compliance and enforcement focus, they did not introduce a blanket requirement for isolation in residential or office towers; rather, they intensified attention to soil-structure interaction, detailing quality, and deformation limits already prescribed by TBDY-2018. [1][5][6]

Occupant comfort criteria and drift/serviceability checks

TBDY-2018 prescribes deformation checks and performance levels for seismic actions, but occupant comfort under wind is governed by serviceability accelerations and drifts derived from wind loading standards and comfort guidelines. For tall coastal buildings, TS EN 1991-1-4 requires consideration of along-wind and cross-wind responses, vortex shedding, and structural damping; these considerations drive dynamic analyses to estimate peak accelerations at occupied floors. ISO 10137 provides recommended thresholds by occupancy category, which for offices and residences typically fall below human perception for frequent winds and are set to reduce motion sickness risk at rarer wind events. In Bayrakli’s taller towers, these thresholds often motivate supplemental stiffness and damping to achieve comfort, confirmed through wind tunnel testing where undertaken. In Karsiyaka’s more moderate-height residential towers, achieving comfort within ISO 10137 limits often remains feasible with code-based wind actions and conventional lateral systems without special devices. [2][3][4]

What this means for a buyer comparing recent projects

For a buyer comparing towers on the Bayrakli and Karsiyaka waterfronts, the underlying legal framework for earthquake resistance is identical: the 2018 national earthquake code governs seismic analysis, detailing, and performance. Differences arise from building height, occupancy, and project delivery norms. Bayrakli’s newer commercial and mixed-use towers more frequently apply wind tunnel studies and explicit comfort targets using international criteria, while Karsiyaka’s residential towers rely on code wind actions and standard serviceability checks. Seismic isolation is legally available but not required for residential or office towers; its common use in Izmir is in critical facilities. Where financial decisions are involved, this information is general in nature; consult a licensed structural engineer or building surveyor for project-specific verification of wind comfort studies, drift checks, and any isolation or damping systems specified.

Related Questions:
– Q# How does Turkey’s 2018 Earthquake Code apply to coastal high-rises in Izmir?
– Q# Are wind tunnel tests required for tall residential towers in Turkey?
– Q# What does AFAD’s hazard map imply for site classification in Izmir?
– Q# When is base isolation recommended under TBDY-2018?

References:
[1] Official Gazette (Resmi Gazete). “Türkiye Bina Deprem Yönetmeliği (2018) – Turkish Building Earthquake Code.” https://www.resmigazete.gov.tr/eskiler/2018/03/20180318M1-1.htm
[2] AFAD. “Turkey Earthquake Hazard Map (Türkiye Deprem Tehlike Haritası).” https://tdth.afad.gov.tr
[3] Turkish Standards Institution (TSE). “TS EN 1991-1-4: Eurocode 1 – Actions on structures – Part 1-4: General actions – Wind actions.” https://intweb.tse.org.tr/Standard/Standard/Standard.aspx?081118051115108051104119110104055047105104120088111043043110104105057111051108100
[4] International Organization for Standardization (ISO). “ISO 10137:2018 – Bases for design of structures — Serviceability of buildings and walkways against vibrations.” https://www.iso.org/standard/67182.html
[5] AFAD. “30 October 2020 Aegean Sea (Izmir) Earthquake Assessment Report.” https://www.afad.gov.tr
[6] Izmir Metropolitan Municipality. “New City Center (Yeni Kent Merkezi) Planning Framework.” https://www.izmir.bel.tr

Disclaimer: This article is for informational purposes only and does not constitute legal, financial, or investment advice. Property law and tax rules in Turkey change frequently. Consult a licensed Turkish lawyer, accountant, or real estate professional before making any purchasing decision.