Experimental analysis of concrete elements under partial area strip loading

Schmidt‐Thrö, Gerald; Smarslik, Mario; Tabka, Bassem; Scheufler, W.; Fischer, Oliver; Mark, Peter

doi:10.1002/cend.201900001

Cited by 9 publications

(17 citation statements)

References 14 publications

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“…The regions of the segment where HPFRC is used are highlighted in red in Figure 3. Additionally, a local welded splitting reinforcement ladder composed of 15 Ø 10 + 15 Ø 10 + 12 Ø 8 rebar (B500A) was adopted (Figure 3), which has been found to provide an improved concrete confinement 23 . The remaining volume of the segment features C70/85 concrete without fiber reinforcement.…”

Section: Reinforcement Proposalmentioning

confidence: 99%

“…The uniaxial compressive behavior of concrete is described by means of the model proposed by Thorenfeldt 30 and compressive strength increase due to lateral confinement was considered by means of the model introduced by Selby and Vecchio 31 . Hence, the combination of material models can capture all relevant effects occurring for concrete elements subjected to high localized compressive stresses (see References 23 and 32).…”

Section: Numerical Validation: Local Behavior Of Longitudinal Jointsmentioning

confidence: 99%

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A hybrid solution proposal for precast tunnel segments

Trabucchi

Smarslik

Tiberti

et al. 2021

Structural Concrete

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The construction of underground structures is playing a relevant role in modern society. As a result of noticeable tunnel boring machine (TBM) evolution, mechanized excavation methods are gaining increased market shares. TBM driven tunnels are generally used in combination with precast concrete segments as the main support system for reducing or minimizing surface disturbances during construction and to fulfill the project requirements with regards to quality, construction times, budget and safety. Within this framework optimization approaches strongly focused on these process parameters, rather than the general structural performance of the segments. However, improving the performance by using conventional reinforcement, High Performance Fiber Reinforced Concretes (HPFRCs) or a combination of such enables a possible reduction of the lining thickness or the amount of reinforcement. To this aim, this paper presents a new hybrid solution for precast tunnel segments with a reduced thickness, which leads to new perspectives in reducing the total amount of concrete, in decreasing the volume of disposal materials from the boring process as well as to minimize the TBM size. A parametric numerical study is developed for evaluating the effectiveness of proposed hybrid solution. The latter is based on high strength reinforced concrete in combination with HPFRC at the longitudinal joints, whose geometric configuration is properly modified to maximize the segment's bearing capacity.

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Section: Reinforcement Proposalmentioning

confidence: 99%

Section: Numerical Validation: Local Behavior Of Longitudinal Jointsmentioning

confidence: 99%

A hybrid solution proposal for precast tunnel segments

Trabucchi

Smarslik

Tiberti

et al. 2021

Structural Concrete

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“…This paper discusses the state of the art of the ultimate limit state (ULS) design according to the European standards [1,2] and presents a new optimized reinforcement design for tubbings with strengthened longitudinal joints. Although there are no analytical models available, a couple of empirical models [3][4][5][6] that describe this specific problem of partially loaded areas in longitudinal joints of tubbings can be found. These models are based on experiments leading to limitations when it comes to applying the models to different configurations or systems.…”

Section: Introductionmentioning

confidence: 99%

Optimized reinforcement in longitudinal joints of segmental tunnel linings

Proksch‐Weilguni

Wolfger

Kollegger

2021

Geomechanics and Tunnelling

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When building tunnels using segmental lining, the segmental lining takes over the supporting role of the excavated soil. With the workspace in tunnel construction being very constricted the circular, segmental linings are divided into small segments called tubbings which are assembled by a tunnel boring machine. This kind of construction results in numerous longitudinal and circumferential joints. The loading situation for the longitudinal joints is typically dominated by the compressive normal forces combined with relatively small bending moments. The thickness of the tubbings usually depends on the longitudinal joints of the individual segments. The cross‐sectional area of the tubbings has to be reduced at the joints in order to avoid spalling of the concrete leading to higher compression in the joints themselves. The Institute of Structural Engineering of TU Wien developed a new reinforcement design for tubbings with strengthened longitudinal joints. With a patent application pending, the newly designed joints were manufactured and tested demonstrating that the TU Wien proposal significantly increases the load‐bearing capacity of the tubbings in comparison to conventional tubbing solutions. The very satisfying results, obtained from the large‐scale tests of the newly developed joint design, show great potential for the construction of tunnels with thinner tubbings in the near future.

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“…In contrast, fiber reinforced concrete (RC) is not obligated to concrete covers and helps to avoid complicated reinforcement patterns in geometrically challenging areas. Hence, it poses a valid alternative or addition to improve the joint's and the segment's overall performance …”

Section: Introductionmentioning

confidence: 99%

Hybrid reinforcement design of longitudinal joints for segmental concrete linings

Smarslik

Mark

2019

Structural Concrete

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In mechanized tunneling, the performance of segmental tunnel lining segments is closely bound to the longitudinal joint design. The guiding local effect is partial area strip loading with predominantly plane load distribution. Current normative standards only inadequately cover this case, which leads to an underestimation of the actual bearing capacities and thus offers considerable optimization potential. A hybrid material concept is proposed to improve the joints' performance, which is based on the results of robust combined trusscontinuum topology optimization. It combines high‐performance steel fiber reinforced concrete in the area of load application with conventional materials used for the remaining regions. A relocation of the gasket to the segments' center proves to provide better protection, and a double hinge neck leads to a more efficient load transfer. The effects of these measures on the structural performance are analyzed experimentally and compared against conventional designs. The results show pronounced increases in bearing capacities by using hybrid reinforcements and provide a quantification of optimization based design modifications.

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Experimental analysis of concrete elements under partial area strip loading

Cited by 9 publications

References 14 publications

A hybrid solution proposal for precast tunnel segments

A hybrid solution proposal for precast tunnel segments

Optimized reinforcement in longitudinal joints of segmental tunnel linings

Hybrid reinforcement design of longitudinal joints for segmental concrete linings

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