Stress-laminated timber (SLT) decks: review of structural types and performance evaluation

Stress-laminated timber (SLT) decks have been widely applied in short- to medium-span bridges due to their cost-effectiveness, rapid construction, and ease of maintenance. However, current knowledge on their structural forms, mechanical behavior, and long-term service performance remains dispersed across experimental studies, bridge case reports, and region-specific applications. This review provides an integrated assessment of SLT decks by synthesizing their main structural types, representative engineering applications, laboratory findings, and field performance. The available evidence indicates that prestress level, prestress retention, interlaminar friction, loading position, deck geometry, lamination joint configuration, prestressing bar spacing, and environmental exposure are the principal factors governing stiffness, load distribution, slip behavior, durability, and long-term reliability. A key insight from the reviewed studies is that the service performance of SLT bridges is controlled not only by the initial structural design, but also by the coupled influence of moisture variation, temperature change, wearing surface condition, and maintenance practice during operation. Major challenges for future development are further identified, including long-term prestress loss prediction, nonlinear interlaminar response, dynamic performance under seasonal variations, and the need for more robust design guidance under diverse service environments. Moreover, the concept of stress-laminated bridge decks is extended to bamboo-based systems, and stress-laminated bamboo and stress-laminated bamboo-timber decks are proposed as promising sustainable alternatives with potential mechanical and environmental advantages. Overall, this synthesis establishes a structured knowledge framework for SLT deck systems and highlights future directions for the development of next-generation stress-laminated bridge decks.