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MODELLING OF REALISTICALLY SIZED AND LOADED FRP CONFINED RECTANGULAR REINFORCED CONCRETE COLUMNS

实际尺寸和负载的 FRP 约束矩形钢筋混凝土柱的建模

基本信息

批准号：
EP/E039901/1
负责人：
Antony Darby
金额：
$ 16.88万
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE039901%2F1
关键词：
MODELLING REALISTICALLY SIZED LOADED FRP

项目摘要

The proposal aims to develop a practical generalised model for analysing realistically dimensioned and loaded rectangular columns strengthened using FRPs. Strengthening circular concrete columns can be achieved by wrapping with FRP (fibre reinforced polymer). This confines the concrete, and can result in increases in load and strain capacity of over 100%. However, most columns are square or rectangular in cross section. Tests, mainly on small-scale rectangular columns, have shown a lower increase in strength, but still up to 50%. A number of simple empirical models have been developed to predict the increase in strength, based upon these small-scale tests. However, , due to size effect, the limited size of columns used in the tests provide little justification for using these models for the larger size rectangular columns found in practice. Thus, a fundamental investigation is required in order to provide a reliable model of behaviour. In order to establish such a general behavioural model there are three fundamental issues which are not well understood, nor limits defined, and therefore need addressing; size effect, aspect ratio and load eccentricity. Confinement of rectangular columns occurs by generating forces at the corners of the column through strain in the FRP, resulting in an effectively confined cruciform region. When the bond between the FRP and the face of the column breaks down, the FRP is no longer effectively anchored to the sides of the column and, ultimately, must strain from corner-to-corner resulting in lower confinement forces for large columns than for small columns with a small side length. For similar reasons, aspect ratio must also be considered. Additionally, as aspect ratio increases, the effectiveness of confinement is known to reduce. Finally, most columns are loaded eccentrically or have combined bending and axial loads. This results in uneven strain distribution across the section and, therefore unequal confining forces at each corner, resulting in a non-cruciform confined area. The behaviour, considering these three issues, will be ascertained via a series of instrumented and monitored tests on large-scale rectangular columns (for comparison with existing small scale test results), together with qualitative finite element modelling to establish the evolution of the shape of the effectively confined area. This information, together with a suitable bond-stress-slip and concrete failure models, will be used to develop an analytical model for strengthening of rectangular columns based upon the mechanics of the behaviour rather than by fitting experimental results.

该提案旨在开发一个实用的通用模型，用于分析现实的尺寸和加载矩形柱加强使用FRP。采用纤维增强复合材料（FRP）对混凝土圆柱进行包裹加固。这限制了混凝土，并可能导致超过100%的负载和应变能力的增加。但是，大多数柱的横截面是正方形或矩形。主要在小尺寸矩形柱上进行的测试显示，强度增加较低，但仍高达50%。根据这些小规模试验，已经开发了一些简单的经验模型来预测强度的增加。然而，由于尺寸效应，试验中所用的柱尺寸有限，对于实际中发现的较大尺寸的矩形柱，几乎没有理由使用这些模型。因此，为了提供可靠的行为模型，需要进行基本的调查。为了建立这样一个通用的行为模型，有三个基本问题，这是没有很好地理解，也没有限制定义，因此需要解决的尺寸效应，纵横比和负载偏心。矩形柱的限制是通过FRP中的应变在柱的拐角处产生力而发生的，从而产生有效限制的十字形区域。当FRP和柱面之间的粘结断裂时，FRP不再有效地锚固到柱的侧面，最终，必须从角到角应变，从而导致大柱的约束力低于具有小边长的小柱。出于类似的原因，还必须考虑纵横比。此外，随着纵横比的增加，限制的有效性已知会降低。最后，大多数柱承受偏心荷载，或承受弯曲和轴向荷载的组合。这导致截面上应变分布不均匀，因此每个角上的约束力不相等，导致非十字形约束区域。考虑到这三个问题，将通过一系列大型矩形柱的仪器化和监测试验（与现有的小规模试验结果进行比较）以及定性有限元建模来确定有效限制区域形状的演变。这些信息，连同一个合适的粘结应力滑移和混凝土破坏模型，将被用来开发一个分析模型，用于加强矩形柱的力学行为的基础上，而不是通过拟合实验结果。