For the design in the ultimate limit state and in the serviceability limit state, we have entered the relevant action combinations manually into the software
Stefan Schum
To take the load off the existing locks on the Moselle between Trier and Koblenz, the Waterways and Shipping Office of Trier has commissioned new locks for Trier and Zeltingen, among other places, which are currently under construction. Both structures will be made in reinforced concrete and will have largely uniform system measurements, with 210 meters of usable length, 12.50 meters’ width, 1.50 meters of freeboard, and rises of 6.0 and 7.25 meters. The lower gates of the existing and new locks are at the same level and side by side. The new canal structures will be filled/emptied via lateral side channels and culverts in the chamber walls. Here, miter gates are used for the lower gates and a pressure segment as the upper gate.
The Zeltingen lock is already finished. The consortium for the new build of the 2nd Zeltingen lock, consisting of the construction companies H. Schorpfeil Bau GmbH und J. Bunte Bauunternehmung GmbH & Co. KG, installed 40,000 cubic meters of concrete and 5,000 tons of reinforcing steel for the locks alone, not including the retaining structures of the excavation.
The 2nd lock in Trier is currently in the design planning phase. Here already, in a very early planning phase, the whole life cycle of the structures was considered. The goal was to avoid laborious renovation works on the locks through reduced joints. Because expansion joints have very often caused high renovation costs in canals in the past.
The plan for the most future-proof and long-lived structure possible foresaw only one continuous structural joint for the 312-meter-long Zeltingen lock, in the transition from the normal chamber area to the lower gates. In the chamber floor and lower sections of the wall with the side channels, no further expansion joints were foreseen in the plans. The Trier lock has been though out one further step ahead: Here, no expansion joints will be included. The experiences gained from the construction of the Zeltingen lock should in any case aid in the realization of the second structure.
These are demanding planning tasks for Frankfurt planning company KHP König und Heunisch Planungsgesellschaft. In the state of Rhineland-Palatinate, the Hesse-based engineers are taking over technical management for the solid structures of the Zeltingen locks. For the Trier lock, the office has been assigned structural planning for the solid structures and the entire excavation for service phases two to six. Further planning partners for building planning and hydraulic steelwork are INROS LACKNER AG and Schömig-Plan Ingenieurgesellschaft.
During the planning and execution works, the entire life cycle of the two locks was always in the foreground, influencing both sides decisively. The Federal Waterways and Shipping Administration (WSV) specifies that the concrete used must fulfill the requirements as per ZTV-W (additional technical contractual stipulations for hydraulic engineering) 215 of 2004, or of 2012 for Trier. This dramatically reduces the allowable temperature range for the material. These limitations apply both to the maximum temperature in the components and to the maximum fresh concrete temperature that the material reaches during concreting. To fulfill these high requirements, especially when casting in summer temperatures, a special concrete recipe had to be developed. In addition, technological measures to reduce the temperature of the starting materials were required.
“The concrete temperature provided numerous demanding problems to solve for our company and for all those involved in the project,” says Stefan Schum Dipl.-Ing. from KHP. Because the concrete temperature, as the engineer explains, decisively influences the strains induced and thus crack formation in young concrete. To ensure durability and serviceability, the engineers from Frankfurt had to provide a crack-reducing reinforcement for the structure. This was oriented by the data sheet “crack reduction for early strains in solid hydraulic engineering structures” from 2004, issued by the Federal Institute for Hydraulic Engineering. They received support in this from Prof. Nguyen Viet Tue from TU Graz, who also leads the König und Heunisch Planungsgesellschaft in Leipzig. Here, among other things, a complex finite element calculation for the required base reinforcement was carried out, in which the temporal sequence of concreting works was also considered.
I addition, the crack-reducing reinforcement must be calculated from the operational loads and later forces: A task in which the RIB software system TRIMAS offered the engineers support.
In the sub-model for the head of the lock, 33 load cases were specified and in total 43 load combinations compiled for non-linear calculation with system alteration through bedding loss. Stefan Schum: “To assess the limits of load-bearing capacity and serviceability, we manually entered the relevant action combinations into the software. In this way, with the aid of TRIMAS, we were able to carry out verification for the curvature with lengthwise and transverse forces, fatigue and crack limitation for the very thick components for all relevant load situations.”
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