Temperature‑Induced Displacement Behavior of a Hybrid Cable‑Stayed and Suspension Bridge Based on Long‑Term Field Monitoring

Abstract Temperature-induced deformation is a dominant component of the long-term response of long-span bridges, yet its behavior under in-service conditions remains insufficiently quantified, particularly for hybrid structural systems. This study investigates the temperature distribution and temperature-induced displacement behavior of the Yavuz Sultan Selim Bridge in Türkiye, a combined cable-stayed and suspension bridge with mixed steel and concrete deck systems, using long-term field measurements supported by numerical analysis. Temperature and displacement data recorded by the bridge’s permanent Structural Health Monitoring System, in continuous operation since 2016, are analyzed to evaluate daily and seasonal thermal effects. Measured deck temperatures are decomposed into effective uniform temperature and sectional temperature gradients, and their relationships with longitudinal and vertical displacements at abutments, tower bearings, and midspan are examined. The results show strong linear correlations between effective deck temperature and longitudinal displacements at supports, while vertical displacements are interpreted as secondary responses associated with longitudinal thermal expansion. At midspan, seasonal temperature variation governs vertical deck displacement, with measured amplitudes comparable to design-stage analytical predictions.