CREEPAGE AND SHRINKAGE MUST ALWAYS BE ACCOUNTED FOR
Not an easy task for Stefan Kleffel, Dipl.-Ing., and his team: “Sub-components of the bridge are exposed to extreme stresses that are only present for a specific period in individual construction phases. This is particularly the case for the bored piles,” the structural engineer explains. Through earth pressure on the abutment walls, which are partially exposed in the construction phases, individual bored pile groups receive strongly eccentric loads. For this reason, the stresses from every construction phase had to be considered. The high load in the various states of construction led, in this case, to particularly high levels of reinforcement when the bending load capacity (GZT) and connected crack formation (GZG) were taken into account.
And that is not all: “Creep and shrinkage are always to be accounted for in the pre-cast composite girders as they influence the verification of load-bearing capacity and also the useability. That is, all system and load changes throughout the construction period must be able to be represented in the FE model,” Stefan Kleffel states, explaining his calculation procedures. Through suitable subdivision of the two largely independent component structures, the modeling expenditure was able to be notably reduced and the processing of statistical calculation kept transparent and efficient. In this bridge, system creepage between the subsections played an important role. Over time differences of up to 150 days, large forces built up in the on-site concrete plates, markedly affecting the assessment of the girders. “Without taking account of these time-dependent effects, an integral construction method for this bridge type cannot be implemented,” Stefan Kleffel continues.
For the demanding calculations and relatively complex assessment of the pile foundations and pre-cast composite concrete girders, the engineers relied on the software programs PONTI and TRIMAS by RIB. The PONTIbetonverbund software system supported them here in conducting calculations for the entire system, also making possible the processing of all required detailed checks. In the above example, a replacement for a relatively simple motorway overpass is described. However, this case shows clearly which special engineering and technological considerations are needed in order to create a new element of road transport while traffic is still running, safely, efficiently and economically.
CREEPAGE AND SHRINKAGE MUST ALWAYS BE ACCOUNTED FOR
Not an easy task for Stefan Kleffel, Dipl.-Ing., and his team: “Sub-components of the bridge are exposed to extreme stresses that are only present for a specific period in individual construction phases. This is particularly the case for the bored piles,” the structural engineer explains. Through earth pressure on the abutment walls, which are partially exposed in the construction phases, individual bored pile groups receive strongly eccentric loads. For this reason, the stresses from every construction phase had to be considered. The high load in the various states of construction led, in this case, to particularly high levels of reinforcement when the bending load capacity (GZT) and connected crack formation (GZG) were taken into account.
And that is not all: “Creep and shrinkage are always to be accounted for in the pre-cast composite girders as they influence the verification of load-bearing capacity and also the useability. That is, all system and load changes throughout the construction period must be able to be represented in the FE model,” Stefan Kleffel states, explaining his calculation procedures. Through suitable subdivision of the two largely independent component structures, the modeling expenditure was able to be notably reduced and the processing of statistical calculation kept transparent and efficient. In this bridge, system creepage between the subsections played an important role. Over time differences of up to 150 days, large forces built up in the on-site concrete plates, markedly affecting the assessment of the girders. “Without taking account of these time-dependent effects, an integral construction method for this bridge type cannot be implemented,” Stefan Kleffel continues.
For the demanding calculations and relatively complex assessment of the pile foundations and pre-cast composite concrete girders, the engineers relied on the software programs PONTI and TRIMAS by RIB. The PONTIbetonverbund software system supported them here in conducting calculations for the entire system, also making possible the processing of all required detailed checks. In the above example, a replacement for a relatively simple motorway overpass is described. However, this case shows clearly which special engineering and technological considerations are needed in order to create a new element of road transport while traffic is still running, safely, efficiently and economically.
CREEPAGE AND SHRINKAGE MUST ALWAYS BE ACCOUNTED FOR
Not an easy task for Stefan Kleffel, Dipl.-Ing., and his team: “Sub-components of the bridge are exposed to extreme stresses that are only present for a specific period in individual construction phases. This is particularly the case for the bored piles,” the structural engineer explains. Through earth pressure on the abutment walls, which are partially exposed in the construction phases, individual bored pile groups receive strongly eccentric loads. For this reason, the stresses from every construction phase had to be considered. The high load in the various states of construction led, in this case, to particularly high levels of reinforcement when the bending load capacity (GZT) and connected crack formation (GZG) were taken into account.
And that is not all: “Creep and shrinkage are always to be accounted for in the pre-cast composite girders as they influence the verification of load-bearing capacity and also the useability. That is, all system and load changes throughout the construction period must be able to be represented in the FE model,” Stefan Kleffel states, explaining his calculation procedures. Through suitable subdivision of the two largely independent component structures, the modeling expenditure was able to be notably reduced and the processing of statistical calculation kept transparent and efficient. In this bridge, system creepage between the subsections played an important role. Over time differences of up to 150 days, large forces built up in the on-site concrete plates, markedly affecting the assessment of the girders. “Without taking account of these time-dependent effects, an integral construction method for this bridge type cannot be implemented,” Stefan Kleffel continues.
For the demanding calculations and relatively complex assessment of the pile foundations and pre-cast composite concrete girders, the engineers relied on the software programs PONTI and TRIMAS by RIB. The PONTIbetonverbund software system supported them here in conducting calculations for the entire system, also making possible the processing of all required detailed checks. In the above example, a replacement for a relatively simple motorway overpass is described. However, this case shows clearly which special engineering and technological considerations are needed in order to create a new element of road transport while traffic is still running, safely, efficiently and economically.
