Influence of Drying on the Seismic Performance of Reinforced Concrete Frame Structures
Experimental Program and Specimen Configuration
A quasi-static cyclic loading experiment was conducted on one-third scale, three-story RC frame buildings. Two environmental conditions were considered: a saturated (wet) condition and a two-year natural drying condition. This comparative setup enabled direct evaluation of drying-induced effects on structural stiffness, deformation characteristics, and damage progression.
Effect of Drying on Initial Stiffness and Stress Transfer
Results reveal a significant reduction in initial stiffness in the dried specimen compared to the saturated specimen. This stiffness degradation is attributed to residual stresses and drying shrinkage cracks, which disrupt the internal stress-transferring mechanisms within the concrete matrix and at reinforcement interfaces. The findings demonstrate that moisture state directly influences global structural rigidity.
Influence on Deformation Patterns and Failure Modes
Distinct deformation behaviors were observed between the two specimens. The wet structure exhibited early localized damage, primarily due to stress concentration effects. In contrast, the dried specimen showed more distributed cracking and damage under the same loading cycle, indicating a shift in failure mode associated with altered material properties and crack development patterns.
Damage Progression and Structural Response
The localized damage in the saturated specimen suggests higher stiffness but reduced deformation capacity at specific regions, while the distributed damage pattern in the dried specimen reflects stiffness degradation but more gradual stress redistribution. These contrasting responses highlight the complex interaction between moisture condition, cracking behavior, and cyclic load resistance.
Implications for Structural Design and Assessment
The study underscores that drying-induced effects, including shrinkage cracking and residual stress redistribution, significantly influence seismic performance and failure characteristics of RC frame systems. These factors should not be neglected in structural design, performance evaluation, and lifecycle assessment of reinforced concrete buildings, particularly in regions subject to long-term environmental exposure and seismic loading.
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