Abstract Cracking effects are the intrinsic attribute of serviceability analysis of reinforced concrete elements. These effects are the research object of numerous studies, which have been carried out for more than half a century. Despite extensive research, there is no commonly accepted methodology for cracking analysis. The existing approaches employ empirical models customised using results of laboratory specimens with simplified geometry that are not able to represent common cracking tendencies adequately. The focus of this experimental study is to examine the influence of the cross-section parameters on the cracking behaviour of concrete elements subjected to tension. The test program encompasses 30 concrete prisms reinforced with multiple bars. Two lengths of the specimens were investigated verifying the comparability of the cracking results of relatively short (500 mm) and long (1210 mm) prisms. All specimens had an identical 150 × 150 mm cross-section. The number and diameter of bars and cover depth were among the test variables. The bars were distributed in the cross-section ensuring 15 mm, 30 mm, 40 mm and 50 mm depth of concrete cover. The cracking results do not support the generally accepted concept that relates crack widths to crack spacing following which the formation of the maximum crack is expected close to the uncracked block having the maximum length. In the tested specimens, the maximum crack was located next to the uncracked block of maximum length in 60% of the considered prisms; the maximum crack occurred between the two blocks whose sum is maximum in only one case. The adequacy of the crack prediction model from Model Code 2010 was also examined, identifying tendencies that point out potential improvements in the model. The modification should address the evidenced inability of the model to predict the correlation between the cover depth and crack width satisfactorily.

中文翻译：

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多条受拉钢筋混凝土棱柱开裂——覆盖效应

摘要 开裂效应是钢筋混凝土构件使用性能分析的内在属性。这些影响是进行了半个多世纪的众多研究的研究对象。尽管进行了广泛的研究，但没有普遍接受的裂缝分析方法。现有的方法采用使用实验室试样的结果定制的经验模型，这些模型具有不能充分代表常见开裂趋势的简化几何形状。本实验研究的重点是检查横截面参数对受拉混凝土构件开裂行为的影响。测试程序包括 30 个用多根钢筋加固的混凝土棱柱。研究了两种长度的试样，以验证相对短 (500 mm) 和长 (1210 mm) 棱柱的开裂结果的可比性。所有试样都有相同的 150 × 150 mm 横截面。钢筋的数量和直径以及覆盖层深度属于测试变量。钢筋分布在横截面上，以确保混凝土覆盖层的深度为 15 毫米、30 毫米、40 毫米和 50 毫米。开裂结果不支持将裂纹宽度与裂纹间距联系起来的普遍接受的概念，在此之后，最大裂纹的形成预计接近具有最大长度的未开裂块。在测试的试样中，最大裂纹位于 60% 所考虑棱柱中最大长度的未裂纹块旁边；最大裂缝发生在两个块之间，其总和只有一种情况。还检查了 Model Code 2010 中裂纹预测模型的充分性，确定了指出模型潜在改进的趋势。修改应该解决模型无法令人满意地预测覆盖层深度和裂缝宽度之间的相关性的问题。