Experimental assessment of crack prediction methods in international design codes for edge restrained walls
Experimental assessment of crack prediction methods in international design codes for edge restrained walls
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DOI：
10.1016/j.istruc.2023.06.087
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发表时间：
2023-09
期刊：
影响因子：
4.1
通讯作者：
Karim El Khoury;Imogen Ridley;R. Vollum;J. Forth;M. Shehzad;A. Elwakeel;N. Nikitas;B. Izzuddin
中科院分区：
文献类型：
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作者：
Karim El Khoury;Imogen Ridley;R. Vollum;J. Forth;M. Shehzad;A. Elwakeel;N. Nikitas;B. Izzuddin
由于早期温度和长期收缩应变的外部约束而导致的裂缝，在建筑行业中是一个重要的问题，因为它会导致挡水和抗渗结构的渗漏。令人担忧的是，最近的一项现场研究发现，约束引起的裂缝宽度经常超过根据英国设计实践(BS EN 1992-3和CIRIA C766)计算的裂缝宽度。由于缺乏相关数据，造成这种情况的原因尚不确定。本文对实验室建造的12个足尺边约束墙的裂缝宽度进行了实测值和预测值的比较。试验考察了混凝土配合比设计、墙体配筋率、墙体高宽比和墙基相对截面积等关键参数对裂缝的影响。对首次开裂时和监测结束时的实测值和计算值进行了比较。测试中注意到了两种类型的行为，这取决于第一次裂缝形成的时间。裂缝要么发生在模板剥离后24小时内的早期，要么由于早期热收缩和收缩的组合受到限制而发生在较晚的时间。尽管最初的裂缝非常窄，但在早期裂缝形成的墙中，最终裂缝宽度最大，有相当大的差距。BS EN 1992-3对早期开裂的两面墙的裂缝宽度给出了最好的估计。C766严重低估了这些墙体的裂缝宽度。在后来开裂的其他10面墙中，C766往往给出了最好的裂缝宽度估计。
Through cracking resulting from external restraint of early-age thermal and long-term shrinkage strain is a significant issue in the construction industry as it causes leakage in water retaining and resisting structures. Concerningly, a recent field study found restraint induced crack widths to frequently exceed crack widths calculated in accordance with UK design practice (BS EN 1992-3 and CIRIA C766). Due to a lack of pertinent data, the reasons for this are uncertain. This paper compares measured and predicted crack widths in a series of 12 full-scale edge restrained walls constructed in the laboratory. The tests examine the influence on cracking of key parameters including concrete mix design, wall reinforcement ratio, wall aspect ratio and relative wall to base cross-sectional area. The measured and calculated crack widths are compared at first cracking and at the end of monitoring. Two types of behaviour were noted in the tests, dependent on when the first cracks formed. Cracking either occurred at early age, within 24 h of stripping the formwork, or later due to restraint of combined early age thermal contraction and shrinkage. The final crack widths were greatest, by a considerable margin, in walls where cracks formed at early age, despite the initial cracks being very narrow. BS EN 1992-3 gives the best estimates of crack width in the two walls that cracked at early age. Crack widths in these walls were significantly underestimated by C766. In the other 10 walls, which cracked later, C766 tends to give the best estimate of crack width.