Strength evaluation of unreinforced early-age masonry structures and their temporary bracing using numerical and experimental studies
Abstract
Masonry construction remains a fundamental choice for buildings due to its durability, energy efficiency, and aesthetic appeal. However, the stability of masonry structures during the early construction stages presents significant challenges. When masonry walls are first erected, the mortar has not yet developed sufficient strength to provide adequate support, leaving the walls vulnerable to lateral forces such as wind. This early-age instability can lead to partial or total collapse, posing serious safety risks to workers and causing material loss. One of the most widely adopted solutions for mitigating instability during construction is temporary bracing. Temporary bracing systems are employed to provide lateral support to masonry walls, ensuring they remain upright until the mortar achieves adequate strength. These systems are essential for maintaining structural integrity in the early stages of construction, preventing accidents, and minimizing material wastage. However, in Canada, existing masonry design standards do not offer comprehensive recommendations for the implementation of bracing, leaving engineers to rely on judgment and experience rather than quantitative design methods. This lack of formalized guidelines introduces uncertainty into construction practices, increasing the potential for failures.
This research aims to develop a more rigorous understanding of early-age masonry behaviour and provide improved methodologies for the design of temporary bracing systems. To achieve this objective, an experimental program was conducted, covering multiple levels of masonry behaviour. At the material level, tests were performed to examine the early-age mechanical properties of mortar, focusing on strength development over time. These tests provided insight into the rate at which masonry gains sufficient strength to resist applied loads. At the assemblage level, experiments were conducted on small masonry specimens to investigate the bond behaviour between mortar and units under different loading conditions, including compression and tension. Finally, full-scale wall tests were performed to analyze the lateral stability of masonry structures under controlled conditions. These large-scale experiments helped quantify the structural response of walls at different curing stages and provided valuable data for validating numerical models.
In parallel with the experimental investigations, a numerical modeling framework was developed to simulate the behaviour of early-age masonry structures. Finite element models were constructed to replicate the physical test conditions, incorporating time-dependent material properties to simulate the evolving strength of mortar. The models were employed to conduct parametric studies, assessing the influence of variables such as wall height, bracing configurations, loading, and environmental factors on overall stability. By comparing numerical results with experimental observations, the research established a reliable predictive guideline for assessing temporary bracing requirements under different construction scenarios.
Based on the experimental and numerical findings, design recommendations and guidelines were developed for the efficient design of temporary bracing, including design tables that offer practical guidelines for ensuring masonry stability during early construction stages. The design temporary bracing guideline bridges the gap between experimental research and practical application, enabling more reliable and standardized approaches to temporary bracing design. The proposed methodology will assist engineers in developing more effective bracing design strategies, reducing the risk of construction-related failures and promoting safer work environments. Additionally, it contributes to optimizing material usage and minimizing construction delays, ultimately leading to more cost-effective and resilient masonry construction.