Bridges are engineering structures that are used to carry traffic routes or supply lines over obstacles such as rivers, valleys or other traffic routes. According to the Federal Ministry for Digital and Transport, there are around 39,500 road bridges with a total length of over 2,100 km in the federal highway network alone. In addition, there are a large number of bridges for state, district and municipal roads.

The majority of bridges in the old federal states were built between the 1960s and 1980s. This applies in particular to large valley bridges such as the Siegtal bridge or the Rahmedetal bridge near Lüdenscheid, which is now famous throughout Germany. Many of the older bridges are in poor condition and will have to be replaced by new structures in the next few years. Without exception, this also applies to all valley bridges and flyover structures on the federal highway 45 (Sauerland line).

This is where the Siegen Construction Day 2024 comes in, which this year will focus on the topic of bridges. The program includes numerous presentations by renowned speakers on current and interesting topics related to road bridges. The content of the Construction Day will include presentations on the new version of the recalculation guideline for solid bridges and the planned expansion of the Sauerland Line as well as modular bridge construction. Bridges will also be presented from an architectural perspective.

The Siegen Construction Day is an event organized by the University of Siegen, supported by the Förderverein für Architektur und Bauingenieurwesen (fab e.v.).

Further information on Bautag 2024 and registration: https://eveeno.com/129339574

At the invitation of OTTO QUAST Bau Aktiengesellschaft students on the Concrete Construction I, Concrete Construction II and Bridge Construction courses visited the precast concrete plant in Freudenberg-Lindenberg on 05.07.2024 as part of an excursion.

The head of work preparation, Mr. Carsten Thamm, welcomed the participants and gave them a tour of the factory premises. He provided information about the work processes and plant technology of the precast plant as well as the special features of factory production and subsequent assembly on the construction site. The route led from the reinforcing steel bending shop to the production halls for sandwich wall elements, stairs, columns and prestressed concrete beams up to 37 m long, as well as to the outdoor area where the finished elements are temporarily stored until they are transported away. The pallet plant for the production of floor slabs and the concrete mixing plant were then inspected.

After the tour, the Managing Director of the precast plant, Mr. Sebastian Koch, presented the company history, locations and business areas as well as career opportunities within the company.

The photo on the left shows the participants of the excursion together with Mr. Carsten Thamm on the outdoor area in front of reinforced concrete columns with formed foundations. The photo on the right shows an external staircase intended for the INCYTE building at the University of Siegen.

This year's bridge construction excursion took place on 21.06.2024 at the invitation of Autobahn GmbH, Westphalia branch, Netphen branch office. The destination was the Eisern and Rinsdorf viaducts south of Siegen, which are being replaced by new structures as part of the A45 expansion project. The participants (left photo, Eisern viaduct in the background) were welcomed on site by Mr. Samuel Freund, head of the Netphen branch office, as well as Ms. Jennifer Johannsen and Mr. Michael Stahl, who provided comprehensive information on the process and current status of the construction project.

The northern sections of the replacement structures for both bridges have already been completed and are open to traffic. Work on the southern substructures is also well advanced. On the Eisern viaduct, the penultimate section of the superstructure (single-cell prestressed concrete box girder) was recently concreted on launching scaffolding (left photo). At the Rinsdorf viaduct (right photo), the final sections of the reinforced concrete deck slab are currently being laid on the steel trough of the superstructure (hollow box girder in steel composite construction), which was built using the incremental launching method. In spring 2025, the northern section of the Rinsdorf viaduct is due to be cross-pushed.

Under the motto "Shaping Transformation", the 68th BetonTage took place at the Congress Centrum Ulm from May 14 to 16, 2024. This year, the leading congress of the concrete and precast concrete industry focused on the challenges and opportunities of the ecological and digital transformation of the construction industry. What contribution can the concrete industry make to this? What impetus can the industry provide and where is there still a need for action? The presentations from science and practice covered a range of topics from lightweight construction and efficient production processes, including digitalization, to serial construction and the circular economy. As usual, the congress was accompanied by an exhibition from the supplier, machinery and software industries.

On the "Concrete in structural design" panel, Professor Torsten Leutbecher presented current approaches to the bending and shear force design of bending beams made of steel fiber-reinforced ultra-high performance concrete (UHPC) in two lectures.

The construction sector consumes around 50-60% of the world's resources and is a major driver of climate change. This fact is forcing a paradigm shift in architecture and construction.

In future, the entire life cycle of a building, from the production of the material through to dismantling and reinstallation, must be taken into account in projects in order to move from linear resource consumption to a circular construction industry.

In addition to the further development of climate-friendly construction methods, quickly implementable solutions are needed for the minimized and efficient use of resources - an essential basis is the existing building stock. Resources have been used in the past that can be used as a great store of resources for our future. This year's Construction Day takes up the topic and discusses various approaches to urban mining. The aim is to initiate a discourse on how the value and resource quality of existing buildings in the Siegerland region can become the focus of planning and construction activities in the future.

The Siegen Building Day is an event of the University of Siegen, supported by the Förderverein für Architektur und Bauingenieurwesen. Information on the 2023 Building Day can be found at www.foerderverein-bauwesen.org.

This year's bridge construction excursion took place on 23.06.2023 at the invitation of Autobahn GmbH, Westphalia branch, Netphen branch office. As in the 2019 summer semester, the destination was the Rinsdorf and Rälsbach valley bridges south of Siegen, which are being replaced by new structures as part of the A45 expansion project. The participants were informed in detail by Mr. Gunther Nöh from Autobahn GmbH about the process and the current status of the construction project.

The northern sections of the new replacement structures for both bridges have already been completed and are open to traffic. The steel trough of the future steel composite cross-section of the southern section of the Rinsdorf viaduct is currently being erected using the incremental launching method (left on the left-hand photo). At the Rälsbach viaduct, the prestressed concrete superstructure of the southern section of the bridge is currently being built in sections on falsework. The photo on the right shows the reinforcement of the two-cell box girder cross-section.

At the invitation of the DRÖSSLER Group 10 students from the Solid Construction I, Solid Construction II and Bridge Construction courses visited the precast concrete plant in Siegen-Eiserfeld on 05.05.2023 as part of an excursion. The managing director, Mr. Christian Drössler, and Ms. Daniele Blömeke, project manager in the technical office of Drössler GmbH Umwelttechnik, first presented the business areas of the group of companies and then guided the participants through the plant.

From the prestressed bed to the production of sandwich elements, the pallet warehouse of the circulation system for wall and ceiling production and the joinery and metalworking shop. During the tour, Mr. Drössler informed the participants about the general work processes in the company, the merchandise management system and quality assurance measures. Outside, the warehouse, the mixing plant and the adjoining warehouse were visited. This is where installation parts, such as shaft anchors and anchor channels, and the monostrands for bondless prestressing are stored.

The picture on the left shows a sandwich wall whose facing shell was produced using a clinker-look formliner. The picture on the right shows several wall elements for a water tank, which were produced with a specially textured exposed concrete surface.

At the invitation of Autobahn GmbH, Westphalia branch, Netphen branch, this year's bridge construction excursion took place on 08.07.2022. The destination was the Eisern viaduct south of Siegen. The participants were informed in detail about the planning and execution of the structure under construction by Ms. Jennifer Johannsen from Autobahn GmbH.

The existing Eisern viaduct dates back to 1967 and, alongside the Rinsdorf and Rälsbach viaducts, is the third and last viaduct between the Siegen-Süd and Wilnsdorf junctions to be demolished and rebuilt. The six-lane expansion of the A45 will then complete the construction work between the Siegen-Süd and Wilnsdorf junctions. The Eisern viaduct has a length of 327 meters and is 50.6 meters high. In 2024, highway traffic is expected to flow over the six-lane bridge.

The photo on the left shows the new prestressed concrete superstructure, which is being built on launching scaffolding. The photo on the right shows the interior of the single-cell box girder with the external tendons not yet stressed.

BetonTage is Europe's largest trade congress for the precast concrete industry. Every year, more than 2,000 participants from 20 nations come to generate knowledge and network in an informal atmosphere. From June 21 to 23, 2022, the BetonTage took place for the first time at the Congress Centrum Ulm. "Sustainable construction with concrete" was the motto of this year's specialist program. Resource-saving techniques in cement and concrete production and the use of innovative concretes and concrete components played a key role in the presentations. There were also reports on the use of innovative construction and production processes as well as outstanding architectural and logistical solutions from the precast concrete and concrete products industry. The plenary presentations and selected panels were streamed live.

On the panel "Concrete in structural design", Professor Torsten Leutbecher reported on the influence of fiber orientation on the mechanical properties of ultra-high-strength steel fiber reinforced concrete.

Mobility is the realized mobility of people, the satisfaction of needs through participation in activities. Mobility is reflected in traffic in the form of changes of location. Mobility is of great importance for the quality of life in both urban and rural areas. Until now, however, traffic has often also been associated with high levels of congestion, poor_{CO2 values}, noise pollution and a lack of space.

Due to high mobility needs in everyday life and leisure, the division of labour and globalization in the movement of goods and the resulting increasing traffic load, current transport concepts are reaching their limits. How can mobility be made more sustainable in the future and reconciled with a high quality of life?

The traffic turnaround with changing mobility is a very relevant topic for both the Department of Civil Engineering and the Department of Architecture. Planning, on the one hand, and implementation, on the other, gives urban development a lot of opportunity for the inner development of squares and large street canyons. Therefore, this topic "New mobility, urban and traffic planning" is perfect for a networking event in the region and is a visible platform for the proximity between the departments of architecture and civil engineering.

The Siegen Construction Day is an event of the University of Siegen, supported by the Association for the Promotion of Architecture and Civil Engineering. Information about Bautag 2022 can be found at www.foerderverein-bauwesen.org.

The 5th HiPerMat Conference, an international symposium on ultra-high performance concrete (UHPC) and high-performance materials, took place at the University of Kassel from March 11 to 13, 2020. Due to the spreading coronavirus pandemic, only 96 of the 190 registered international guests were able to attend in person.

At the conference, Kevin Metje from the Chair of Concrete Structures presented the results of his experimental investigations into the shear load-bearing behavior of UHPFRC beams with a compact cross-section. Further information

Professor Torsten Leutbecher gave a presentation in the session in honor of Professor Ekkehard Fehling, who celebrated his 60th birthday in October 2019, on the compressive load-bearing behavior of ultra-high performance concrete cracked in shear. The presentations could also be followed as a livestream.

Every year in February, the concrete (precast) industry meets at BetonTage in Neu-Ulm. In 2020, the industry event took place for the 64th time and presented itself with new content, formats and target groups as well as an additional congress day. Despite the fear of the coronavirus, almost 2,300 participants attended the traditional event at the Edwin-Scharff-Haus congress center from 18 to 21 February 2020. Under the motto "Concrete construction of the future - lightweight, resource-efficient,_CO2-neutral", they learned about the latest developments and trends in building with concrete.

The topic of Professor Torsten Leutbecher's presentation on the panel "From research to practice" was the background and test methods for classifying ultra-high-strength concrete.