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，大约四分之一的库存是坚固的砖结构。每年，由于季节性和挖掘引起的地面运动，成千上万的这类建筑物经历结构性破坏。为了了解和管理地面运动对这些历史资产的影响，有必要深入了解其材料。因此，MINT的主要动机是估计现有砌体资产的力学性能，并有机会利用改进的测量和解释技术，通过新的原位测试挑战材料性能数据的有限可用性。表征砖砌体材料力学性能的标准技术需要广泛的取样和破坏性测试。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，在其目前的形式，标准的现场测试提供有限的材料性能的信息。MINT项目旨在开发一种轻微破坏性的原位测试方法，以确定历史砖砌体材料的关键宏观变形能力和强度参数。该方法将联合收割机非传统的扁平千斤顶测试与明确的数字图像相关（DIC）应变测量和快速虚拟场方法（VFM）算法相结合，以克服标准材料表征技术的局限性。它将使我们收集有关砖砌体材料的详细力学信息的能力发生重大变化，并释放数值模拟的潜力，以可靠地评估结构响应。据设想，这种新的能力也将使更明智的决定改造和维修。长远而言，MINT的发展将有助提高建造业的生产力，以及改善市民的福利。MINT项目的目标如下：1.用数值方法研究不同的平千斤顶和槽布置，以确定一系列砖墙的合适测试程序（工作包WP 1）。了解DIC参数如何影响砌体中的应变测量，并为现场测试制定合适的测量程序（WP 2）。3.基于DIC数据和VFM算法（WP 3），发展了现场识别砌体宏观变形和强度参数的理论.量化现场测试不确定性（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（WP 3）。在实验室中用特性良好的材料建造砖墙。对这些墙应用现场材料识别技术，并评估识别参数与预期值的一致性（WP 4 -5）6。对墙壁进行进一步的加载实验，并评估具有已识别参数属性的数值模型盲预测响应的能力（WP 5）。该项目属于EPSRC结构工程研究领域的福尔斯。项目合作伙伴包括材料测试和技术公司MatchID、在商业有限元软件中开发了最先进的砌体本构模型的DIANA FEA公司、领先的顾问公司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.