Full scale tests and a progressive failure model to simulate full mechanical behavior of concrete tunnel segmental lining joints

2021 ◽  
Vol 110 ◽  
pp. 103834
Author(s):  
Yue Qiu ◽  
Xiongyu Hu ◽  
Gabriel Walton ◽  
Cong He ◽  
Chuan He ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Progressive Failure ◽  
Full Scale ◽  
Failure Model ◽  
Segmental Lining ◽  
Full Scale Tests

scholarly journals Modeling Material Failure During Cab Car End Frame Impact

2009 ◽  
Author(s):  
Richard Stringfellow ◽  
Christopher Paetsch
Keyword(s):  
Static Loading ◽  
Full Scale ◽  
Test Material ◽  
Material Strength ◽  
Model Parameters ◽  
Material Failure ◽  
Failure Model ◽  
Shell Elements ◽  
Fea Model ◽  
Full Scale Tests

New standards have been proposed to increase the strength requirements for cab car end structures and impose further requirements on their ability to absorb energy during a grade-crossing collision [1, 2]. To aid in the development of these new standards, the Federal Railroad Administration (FRA) and the Volpe Center recently completed a set of full-scale tests aimed at assessing the quasi-static and dynamic crush behavior of these end structures. In support of this testing program, end frames designed to meet the new standards were fabricated and retrofitted onto the forward end of an existing cab car. A series of large-deformation quasi-static and explicit dynamic finite element analyses (FEAs) were performed to evaluate the performance of the design. Based on the results of a 2002 full-scale test in which a heavy steel coil impacted the corner post of an end frame built to these new standards, some fracture was expected in certain key end frame components during the tests. For this reason, a material failure model, based on the Bao-Wierzbicki fracture criterion [3], was implemented in the FEA model of the cab car end frame using ABAQUS/Explicit. The FEA model with material failure was used to assess the effect of fracture on the deformation behavior of cab car end structures during quasi-static loading and dynamic impact and, in particular, the ability of such structures to absorb energy. The failure model was implemented in ABAQUS/Explicit for use with shell elements. A series of preliminary calculations were first conducted to assess the effects of element type and mesh refinement on the deformation and fracture behavior of structures similar to those found on cab car end frames, and to demonstrate that the Bao-Wierzbicki failure model can be effectively applied using shell elements. Model parameters were validated through comparison to the results of the 2002 test. Material strength and failure parameters were derived from test data for A710 steel. The model was then used to simulate the three full-scale tests that were conducted during 2008 as part of the FRA program: a collision post impact, and quasi-static loading of both a collision post and a corner post. Analysis of the results of the two collision post tests revealed the need for revisions to both the design of some key end frame components and to key material failure parameters. Using the revised model, pre-test predictions for the outcome of the corner post test were found to be in very good agreement with test results.

scholarly journals SCC and conventional concrete on site: property assessment

2009 ◽  
Vol 2 (1) ◽  
pp. 25-36 ◽  
Author(s):  
S. Nunes ◽  
H. Figueiras ◽  
J. Sousa Coutinho ◽  
J. Figueiras
Keyword(s):  
Mechanical Behavior ◽  
Full Scale ◽  
Hardened Concrete ◽  
Conventional Concrete ◽  
Full Size ◽  
Uniform Strength ◽  
Property Assessment ◽  
Full Scale Tests ◽  
Precast Elements

The present paper deals with comparing properties of hardened SCC cast during first full-scale tests in a precast factory and similar conventional concrete currently used in the same factory. The main goal was to evaluate viability of replacing the C45/55 conventional concrete, in use at the precast factory, by a SCC of the same class of resistance and maintaining the constituent materials. A wide number of specimens (cubes, cylinders, prisms) and full size precast elements were cast with both SCC and conventional vibrated concrete to enable comparing different properties of both types of hardened concrete. In order to implement SCC in this precast factory, suitability of actual current processes involved in production, mixing, transport and placing had to be evaluated. SCC exhibited improved mechanical behavior, higher resistance to fluid ingress and a more uniform strength along the full-size element due to a combination of proper mixdesign together with controlled mixing and placing on site.

Investigation of planing craft maneuverability using full-scale tests

2021 ◽  
pp. 147509022110303
Author(s):  
Kazem Sadati ◽  
Hamid Zeraatgar ◽  
Aliasghar Moghaddas
Keyword(s):  
Full Scale ◽  
Performance Characteristics ◽  
Forward Speed ◽  
Speed Reduction ◽  
Planing Craft ◽  
Full Scale Tests ◽  
Turning Maneuver

Maneuverability of planing craft is a complicated hydrodynamic subject that needs more studies to comprehend its characteristics. Planing craft drivers follow a common practice for maneuver of the craft that is fundamentally different from ship’s standards. In situ full-scale tests are normally necessary to understand the maneuverability characteristics of planing craft. In this paper, a study has been conducted to illustrate maneuverability characteristics of planing craft by full-scale tests. Accelerating and turning maneuver tests are conducted on two cases at different forward speeds and rudder angles. In each test, dynamic trim, trajectory, speed, roll of the craft are recorded. The tests are performed in planing mode, semi-planing mode, and transition between planing mode to semi-planing mode to study the effects of the craft forward speed and consequently running attitude on the maneuverability. Analysis of the data reveals that the Steady Turning Diameter (STD) of the planing craft may be as large as 40 L, while it rarely goes beyond 5 L for ships. Results also show that a turning maneuver starting at planing mode might end in semi-planing mode. This transition can remarkably improve the performance characteristics of the planing craft’s maneuverability. Therefore, an alternative practice is proposed instead of the classic turning maneuver. In this practice, the craft traveling in the planing mode is transitioned to the semi-planing mode by forward speed reduction first, and then the turning maneuver is executed.

scholarly journals Numerical simulation method for predicting a flood hydrograph due to progressive failure of a landslide dam

Landslides ◽  
2021 ◽  
Author(s):  
S. Takayama ◽  
S. Miyata ◽  
M. Fujimoto ◽  
Y. Satofuka
Keyword(s):  
Field Experiments ◽  
Failure Modes ◽  
Initial Conditions ◽  
Progressive Failure ◽  
Landslide Dam ◽  
Failure Model ◽  
Reservoir Water ◽  
Erosion Model ◽  
Flood Hydrograph ◽  
Overtopping Erosion

AbstractReducing the damage due to landslide dam failures requires the prediction of flood hydrographs. Although progressive failure is one of the main failure modes of landslide dams, no prediction method is available. This study develops a method for predicting progressive failure. The proposed method consists of the progressive failure model and overtopping erosion model. The progressive failure model can reproduce the collapse progression from a dam toe to predict the longitudinal dam shape and reservoir water level when the reservoir water overflows. The overtopping erosion model uses these predicted values as the new initial conditions and reproduces the dam erosion processes due to an overtopping flow in order to predict a flood hydrograph after the reservoir water overflows. The progressive failure model includes physical models representing the intermittent collapse of a dam slope, seepage flow in a dam, and surface flow on a dam slope. The intermittent collapse model characterizes the progressive failure model. It considers a stabilization effect whereby collapse deposits support a steep slope. This effect decreases as the collapse deposits are transported downstream. Such a consideration allows the model to express intermittent, not continuous, occurrences of collapses. Field experiments on the progressive failure of a landslide dam were conducted to validate the proposed method. The progressive failure model successfully reproduced the experimental results of the collapse progression from the dam toe. Using the value predicted by the progressive failure model, the overtopping erosion model successfully reproduced the flood hydrograph after the reservoir water started to overflow.

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