MINT: Masonry in-situ testing and material identification

英国拥有欧洲最古老的建筑群之一。在英格兰，大约四分之一的建筑是实心砖砌建筑。每年都有成千上万这样的建筑由于季节性和挖掘引起的地面运动而遭受结构破坏。为了理解和管理地面运动对这些历史资产的影响，对其材料的深入了解是必要的。因此，MINT的主要动机是评估现有砌体资产的力学性能，并利用改进的测量和解释技术，通过新的原位测试来挑战材料性能数据的有限可用性。表征砖砌体材料机械性能的标准技术需要大量的抽样和破坏性测试。因此，这些技术很少应用于现有建筑。材料的原位测试和表征是一种很有前途的替代方法。然而，在目前的形式下，标准的原位测试只能提供有限的材料特性信息。MINT项目旨在开发一种小破坏的原位测试方法，以识别历史砖砌体材料的关键宏观变形能力和强度参数。该方法将非常规的平面千顶测试与明确的数字图像相关（DIC）应变测量和快速虚拟场法（VFM）算法相结合，以克服标准材料表征技术的局限性。它将为我们收集砖砌体材料的详细机械信息的能力带来一个台阶的变化，并释放数值模拟的潜力，以可靠地评估结构响应。预计这种新功能还将使改造和维修方面的决策更加明智。从长远来看，薄荷厂的发展将有助于提高建造业的生产力，并改善公众的福利。MINT项目的目标如下：数值探索不同的平千斤顶和槽布置，以确定适合一系列砖砌体墙的测试程序（工作包WP1）。了解DIC参数如何影响砌体应变测量，并制定合适的原位测试测量程序（WP2）。3 .发展基于DIC数据和VFM算法（WP3）的砌体宏观变形能力和强度参数原位识别理论。量化原位测试不确定性（例如千斤顶载荷分布）、测量噪声和建模偏差对材料识别的影响（WP3）。在实验室用特性良好的材料建造砖砌体墙。对这些墙体应用原位材料识别技术，并评估识别参数与期望值的一致性（WP4-5）。进一步在墙体上进行加载试验，并对识别出参数属性的数值模型盲目预测响应的能力进行评价（WP5）。该项目属于EPSRC结构工程研究领域。项目合作伙伴包括材料测试和技术公司MatchID、DIANA FEA公司（在商业有限元软件中开发了最先进的砌体本构模型）、领先的咨询公司Buro Happold以及材料开发和测试公司Lucideon。

The UK has one of the oldest building stocks in Europe. In England, around a quarter of this stock is of solid brickwork construction. Every year, thousands of such buildings experience structural distress due to seasonal and excavation-induced ground movements. To understand and manage the impact of ground movements on these historic assets, an in-depth knowledge of their materials is necessary. Therefore, the primary motivation for MINT is to estimate mechanical properties of existing masonry assets and the opportunity to challenge the limited availability of data on material properties with new in-situ tests, using improved measurement and interpretation techniques.Standard techniques for characterising the mechanical properties of brick masonry materials require extensive sampling and destructive testing. As a result, these techniques are rarely applied to existing buildings. In-situ testing and characterisation of materials is a promising alternative. However, in their current form, standard in-situ tests provide limited information on material properties. The MINT project aims to develop a minor-destructive in-situ testing method to identify the key macro-scale deformability and strength parameters of historic brick masonry materials. This method will combine unconventional flat jack testing with unambiguous Digital Image Correlation (DIC) strain measurements and rapid Virtual Fields Method (VFM) algorithms to overcome the limitations of standard material characterisation techniques. It will deliver a step change in our ability to collect detailed mechanical information on brick masonry materials and unlock the potential of numerical simulations to reliably assess structural response. It is envisioned that this new capability will also enable more informed decisions on retrofit and repair. In the longer term, the developments from MINT will contribute to improve productivity in the construction sector, and the welfare of the general public.The objectives of the MINT project are listed below:1. Numerically explore different flat jack and slot arrangements to determine suitable testing procedures for a range of brick masonry walls (Work Package WP1).2. Understand how DIC parameters impact strain measurements in masonry and develop suitable measurement procedures for in-situ tests (WP2).3. Develop the theory to identify masonry macro-scale deformability and strength parameters in-situ based on DIC data and VFM algorithms (WP3).4. Quantify the influence of in-situ test uncertainties (e.g. jack loading distribution), measurement noise and modelling bias on material identification (WP3).5. Construct brick masonry walls in the laboratory from well-characterised materials. Apply in- situ material identification techniques to these walls and evaluate the consistency of identified parameters with the expected values (WP4-5)6. Conduct further loading experiments on walls and evaluate the ability of numerical models with the identified parameter properties to blindly predict the response (WP5).This project falls within the EPSRC Structural Engineering research area. Project partners include the materials testing and technology company MatchID, company DIANA FEA which have developed state of the art masonry constitutive models in commercial FE software, leading consultants Buro Happold as well as the material development and testing company Lucideon.