PSI - Issue 78

Yavuz Yadim et al. / Procedia Structural Integrity 78 (2026) 1895–1902

1900

(a)

(b)

(c)

(d)

Fig. 5. Recurring examples of serious defects in RC structures: (a) low-quality concrete; (b) corrosion of steel bars; (c) and (d) non-engineered detailing of the cross-section with lack of stirrup densification at the nodes.

The widespread use of low-quality concrete, inadequate reinforcement, and poor-quality masonry poses significant risks to Turkey’s earthquake-prone regions. These substandard materials lack the ductility and energy dissipation capacity required to withstand seismic forces, rendering structures susceptible to brittle failure modes. Common failure mechanisms include shear failures in columns and walls, and connection failures between structural elements. Addressing these challenges requires a multifaceted approach involving stricter building code enforcement, enhanced quality control protocols, and comprehensive education and training for construction professionals. These measures are essential to ensure the consistent use of appropriate materials and construction techniques aligned with the seismic resistant design principles. A particular area of concern lies in the detailed deficiencies in beams and columns, particularly the inadequate provision of stirrups for shear reinforcement. Such deficiencies often lead to brittle shear failure in columns. While modern seismic codes prescribe capacity design principles to prevent these failures, implementation on construction sites across Turkey remains insufficient owing to limited auditing and enforcement. This gap in applying contemporary building standards has left many of Turkey’s building stock vulnerable—a vulnerability tragically underscored by recent earthquake-induced collapses attributed to inadequate shear reinforcement in columns. Representative examples of these damages are shown in Figs. 5 and 6.

Fig. 6. Example of columns with shear damage. Note the reduced cross-section of the concrete columns and low amount of longitudinal reinforcement. In many cases, the stirrups were placed at a spacing greater than 20 cm near the column-beam joints. 3. Development of seismic codes and construction practice in Turkey Turkey’s seismic code evolved along with its earthquake history. The first national code appeared in 1940 after the 1939 Erzincan Earthquake, prescribing a fixed lateral force of 3% of the building weight without considering structural or soil factors. Revisions in 1947 and 1953 made minor changes, whereas the 1968 update after the 1967 Adapazarı