P 1530 - Extension of the process limits in GMAW hot-wire welding by adapting the material and energy input by means of upstream hot-wire preheating

P 1537 - Wood-steel hybrid construction methods using the example of bending-stressed load-bearing elements The construction industry is the largest CO2 emitter in Germany. The sustainable reorganisation of the construction industry is therefore crucial for a successful fight against climate change. As a renewable building material, wood can help to replace conventional CO2-intensive building materials. However, building with wood also has its limitations. For example, the necessary cross-sections become very large when large spans are required. This is where the completed research project "Wood-steel hybrid construction methods using the example of bending-stressed load-bearing elements - HoStaBau" comes in. By favourably combining the materials steel and timber, hybrid cross-sections are to be constructed that significantly reduce the required cross-sectional dimensions. The materials wood and steel can optimally complement each other in hybrid cross-sections and compensate for the weaknesses of the other material. The research project is divided into eight work packages (WPs). Firstly, analytical and numerical parameter studies show that the materials can be combined very well with different geometry combinations. Subsequently, composite methods are analysed using a total of 106 test specimens. It is shown that the assumption of a full bond can be confirmed by the adhesive bonding of the materials. The durability of the bond is tested with endurance tests (NKL 1 and NKL 2), moisture cycling, high temperature and ageing tests. The adhesive bond can be categorised as uncritical in these areas. In 4-point bending tests, the bending load-bearing behaviour of 30 hybrid beams with different geometry and material combinations with a span of 2.4 m is examined. The load-bearing capacity can be increased by up to 120 % and the bending stiffness by up to 250 % compared to timber reference beams. In addition to the bending load-bearing behaviour, the shear load-bearing behaviour is also being investigated. For this purpose, 18 hybrid beams with different material and geometry combinations and a span of 0.74 m are tested in 3-point bending tests. The shear strength can be increased by up to 440% compared to timber reference beams. At the end of the research project, a standardised design concept for the hybrid construction method will be developed. Based on the test results, the full bond between the materials can be confirmed so that an easy-to-use analytical design method can be created. This enables a rapid transfer into practice. Small and medium-sized enterprises (SMEs) in particular benefit from the research results and gain a knowledge advantage. The goal of the research project was achieved. Publication: April 2024 Authors: P. Haase, S. Aurand, J. Boretzki, Dr.-Ing. M. Albiez, Dr.ir. C. Sandhaas, Prof. Dr.-Ing. P. Dietsch, prof. Dr.-Ing. T. Ummenhofer