High-strength Top700 reinforcing steel as a lever for reducing emissions in diaphragm wall construction
The EU has committed to achieving climate neutrality by 2050 to counteract climate change. As a result, the construction industry is also extensively seeking ways to reduce Global Warming Potentials (GWP). The possibilities to achieve this goal depend on various factors, such as the specific component, the materials used, and the construction method. In this report based on a life cycle analysis of the construction of a diaphragm wall intended for temporary excavation support the possible measures to reduce the GWP are examined. The focus is on the use of two different types of steel: a standard B500B reinforcing steel and the high-strength Top700 (B700B) reinforcing steel from Steeltec AG, which has a 40% higher yield strength. Furthermore, reductions in cross-sectional thickness and a switch to a clinker-reduced binder in concrete production are considered. The study demonstrates that in addition to the main influence factors – concrete volume and clinker content – the use of Top700 instead of B500B can further reduce the GWP during diaphragm wall construction.
Component tests on reinforced concrete slabs with novel types of void formers
The arrangement of void formers in reinforced concrete slabs enables efficient use of materials and provides an important contribution to sustainable and low-emission construction. With the appropriate arrangement of void formers, the flexural strength of the slabs remains virtually unchanged compared to otherwise identical solid slabs. However, their shear strength is reduced by the void formers. In order to make the best possible use of the potential of void former construction, void former shapes are of interest that reduce the shear strength of the respective slab only slightly while providing the highest possible volume displacement. The article describes eight component tests on reinforced concrete slabs with innovative, alternating truncated cone-shaped void formers. Slabs made of both normal concrete and concrete with recycled aggregates were tested. In addition to the load-bearing tests, the recycling potential of the voided slabs was analyzed. The component tests carried out revealed shear strengths of up to 65 % of the load-bearing capacities of otherwise identical solid slabs. The material obtained during the recycling process of the voided slabs met the requirements for the material composition of type 1 recycled aggregate in accordance with DIN 4226-101.
This article deals with the fracture-mechanical simulation of concrete members within the framework of the FE method, with a focus on the use of smeared crack models. Following an introduction to common simulation approaches, the smeared crack model and its two variants, the “Rotated” and “Fixed” smeared crack approaches, are presented and numerically validated. Two laboratory tests were simulated for each of the three failure mechanisms (bending, shear, and punching), using both approaches. The results were then compared with experimental data. It was found that the fixed crack approach realistically reproduced the load-bearing behavior of the beams and slabs investigated. The ultimate loads and observed crack patterns showed good agreement with the experimental results. The pure rotated crack approach, on the other hand, leads to larger deviations depending on the respective failure mechanism. Overall, the study shows that the Smeared Crack Model, together with the presented application recommendations, is well suited to represent the complex load-bearing behavior of concrete members – from laboratory tests and damage analyses to the simulation of detailed points in practical design and product development.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：