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size-dependent punching shear failure of thick reinforced concrete slabs

厚钢筋混凝土板尺寸相关的冲剪破坏

基本信息

批准号：
183030433
负责人：
Professor Dr.-Ing. Peter Mark
金额：
--
依托单位：
Lehrstuhl für Massivbau
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/183030433?language=en
关键词：
size dependent punching shear failure

项目摘要

Experimental investigations of reinforced concrete (RC) slabs with significant thickness still represent a major challenge in civil engineering. Above all hardly manageable dimensions of test specimen, associated self-weights, and appropriate test-loads are responsible for conventional test-setups and concepts currently facing true limits. This explains why undamped intensive international research on the punching shear behavior of RC slabs has been limited to comparatively thin members and thus does not cover the total practical range of recent application that probably rises further in the future. Despite these experimental deficits semi-empirical design rules (EC 2, ACI 318, MC 2010) have been derived from the available data basis and must be applied to cases beyond the intended scope. Thus, extrapolation of experimental results is necessary which introduces additional uncertainty to prognoses of the punching shear failure due to the size effect. Whether potential safety issues arise thereof and how big these might be cannot be quantified without testing thick RC slabs. Also physically well-interpretable models based on these data which have been proposed yet need further verification by large scale tests. The general concept continuously developed and enhanced in the previous project phases aims to resolve the deficit directly, enabling for punching shear tests of really thick RC slabs for the first time. Inspired by numerical simulation, experimental demands concerning space, test-setup, devices and loads are significantly reduced accounting for (multiple) symmetry of specimens consequently. This allows for testing of clearly thicker RC slabs employing the infrastructure already at hand. Once having successfully minimized unintentionally stiff friction-links in the current phase and having restricted to demonstrate the test set-up´s validation of functionality to 30 cm thick RC slabs as directed by the reviewers before, now 70 cm thick RC slabs shall be finally tested. At first, this requires to build the adequate and large-scale concrete-made supports finally, which have been deferred so far. Next is to consequently verify the then up-scaled concept employing appropriate but symmetrically reduced beams again. Finally, the proposal contains two test series. The first enables to quantify the size effect by testing of strictly and truly up-scaled RC slabs without reinforcement while the second one captures the different potential failure mechanisms of reinforced concrete slabs experimentally.

在土木工程中，对具有较大厚度的钢筋混凝土（RC）板的试验研究仍然是一个重大挑战。最重要的是，难以管理的试样尺寸，相关的自重和适当的测试载荷是传统的测试设置和概念目前面临真正的限制。这就解释了为什么国际上对钢筋混凝土板冲剪性能的无阻尼密集研究仅限于相对较薄的构件，因此没有涵盖最近应用的全部实际范围，这些应用可能在未来进一步增加。尽管存在这些实验缺陷，但半经验设计规则（EC 2，ACI 318，MC 2010）已从现有数据基础中推导出来，必须应用于预期范围以外的情况。因此，有必要外推实验结果，这会因尺寸效应而给冲切破坏的预测带来额外的不确定性。如果不对厚钢筋混凝土板进行测试，就无法量化是否会出现潜在的安全问题以及这些问题有多大。基于这些数据提出的物理上可解释的模型还需要通过大规模试验进一步验证。在之前的项目阶段中不断发展和增强的总体概念旨在直接解决缺陷，首次实现真正厚的RC板的冲切试验。受数值模拟的启发，考虑到试样的（多重）对称性，实验对空间、测试装置、设备和载荷的要求显著降低。这允许使用现有的基础设施对明显较厚的RC板进行测试。一旦在当前阶段成功地最大限度地减少了非故意的刚性摩擦连杆，并按照评审员之前的指示，将测试装置的功能验证限制在30 cm厚的RC板上，现在应最终测试70 cm厚的RC板。首先，这就要求最终建造足够的大型混凝土支架，这一直被推迟。接下来是再次采用适当但对称减小的光束来验证当时的放大概念。最后，该提案包含两个试验系列。第一个能够量化的尺寸效应，通过测试严格和真正的放大RC板没有钢筋，而第二个捕获不同的潜在的破坏机制的钢筋混凝土板实验。