MODELING OF MODELS ON FAILURE MODES OF CAISSON - RUBBLE MOUND STRUCTURE IN 1G FIELD TESTS

2021 ◽  
Vol 77 (2) ◽  
pp. I_769-I_774
Author(s):  
Tatsuya MATSUDA ◽  
Tatsuya UEDA ◽  
Kentaro TAMURA ◽  
Naoto NAITO ◽  
Naoki KUWABARA ◽  
...  
Keyword(s):  
Failure Modes ◽  
Field Tests ◽  
Mound Structure ◽  
Rubble Mound

scholarly journals Experimental and Numerical Study of Polymer-Retrofitted Masonry Walls under Gas Explosions

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 863
Author(s):  
Meng Gu ◽  
Xiaodong Ling ◽  
Hanxiang Wang ◽  
Anfeng Yu ◽  
Guoxin Chen
Keyword(s):  
Coating Thickness ◽  
Failure Modes ◽  
Numerical Study ◽  
Field Tests ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Economic Losses ◽  
Masonry Walls ◽  
Spray Pattern ◽  
Gas Explosions

Unreinforced masonry walls are extensively used in the petrochemical industry and they are one of the most vulnerable components to blast loads. To investigate the failure modes and improve the blast resistances of masonry walls, four full-scale field tests were conducted using unreinforced and spray-on polyurea-reinforced masonry walls subjected to gas explosions. The results suggested that the primary damage of the unreinforced masonry wall was flexural deformation and the wall collapsed at the latter stage of gas explosion. The presence of polyurea coatings could effectively improve the anti-explosion abilities of masonry walls, prevent wall collapses, and retain the flying fragments, which would reduce the casualties and economic losses caused by petrochemical explosion accidents. The bond between the polymer and masonry wall was critical, and premature debonding resulted in a failure of the coating to exert the maximum energy absorption effect. A numerical model for masonry walls was developed in ANSYS/LS-Dyna and validated with the test data. Parametric studies were conducted to explore the influences of the polyurea-coating thickness and spray pattern on the performances of masonry walls. The polyurea-coating thickness and spray pattern affected the resistance capacities of masonry walls significantly.

Experimental Studies on Blast-Resistance of HFR-LWC Beams Enhanced with Membrane Action

2020 ◽  
Vol 20 (12) ◽  
pp. 2050142
Author(s):  
Wanxiang Chen ◽  
Lisheng Luo ◽  
Fanjun Meng ◽  
Hang Sun
Keyword(s):  
Failure Modes ◽  
Blast Resistance ◽  
Experimental Studies ◽  
Field Tests ◽  
Lightweight Aggregate ◽  
Failure Pattern ◽  
Lightweight Aggregate Concrete ◽  
Hybrid Fibers ◽  
Membrane Action ◽  
Close Range

Support-induced membrane action can enhance the resistance, while altering the failure pattern, of reinforced concrete (RC) members under static/dynamic loadings. Nevertheless, the membrane effect on the load-response is regarded as a safety factor in current design guides, hence, a thorough understanding of the resistance capability of RC members in the presence of membrane actions is considered essential. To quantitatively depict the membrane behavior and its influence on the blast-resistance and failure pattern of Hybrid Fiber Reinforced-Lightweight Aggregate Concrete (HFR-LWC) beams, a specially built end-constraint clamp is developed to provide membrane actions on the structural component subjected to the blast load simultaneously. A series of field tests are conducted to investigate the dynamic behaviors of the HFR-LWC beams under close-range detonations. Overpressure-time histories of shock waves induced by the close-range explosive charge are captured. Then the deflection-responses and failure modes of the HFR-LWC beams are further investigated. The responses of the clamped HFR-LWC beam under blast loadings can be well simulated, and the blast-resistances of the beam-type members with membrane action are evaluated reasonably. The results show that membrane action is beneficial for the bridging effects of hybrid fibers and the interlocking effects of coarse aggregate, thereby giving rise to the ductile failures of HFR-LWC beam. The maximum deflections of the clamped HFR-LWC beam decrease by about 60% compared with simply-supported HFR-LWC beam in this paper, illustrating that the blast-resistance may be seriously underestimated if the membrane effects are ignored in structural design.

scholarly journals Indentation Tests to Investigate Ice Pressures on Vertical Piers

1977 ◽  
Vol 19 (81) ◽  
pp. 301-312 ◽  
Author(s):  
K. R. Croasdale ◽  
N. R. Morgenstern ◽  
J. B. Nuttall
Keyword(s):  
Strain Rate ◽  
Failure Modes ◽  
Field Tests ◽  
Small Scale ◽  
Initial Contact ◽  
Lake Ice ◽  
Indentation Tests ◽  
Ice Strength ◽  
Unconfined Strength ◽  
The Relationship

Abstract Controlled field and laboratory tests were performed to investigate the relationship between ice strength and the maximum ice pressures on vertical piers. The apparatus used in the field tests consisted of a flat indentor (75 cm wide) which was pushed through the ice by hydraulic rams. 27 tests were conducted on lake ice up to one metre thick. Ice pressures in the range 2.5 to 5.0 MPa were obtained for ice in good initial contact with the indentor. The ice pressures exhibited little sensitivity to variations in temperature, ice thickness and strain-rate for the range 7.5 × 10-7 to 4.4 × 10-3 s-1. The average unconfined compressive strengths obtained in the laboratory were about 20% higher than the average field ice pressures. In addition, the laboratory strengths were found to be sensitive to temperature, and to strain-rate in the range 1 × 10-7 to 1 × 10-3 s-1. The confined compressive strength was two to three times the unconfined strength. The failure modes observed in the indentation tests were similar to those predicted (before the tests) by an upper-bound plasticity model. The ability of the model to relate small-scale ice strength to field ice pressures is discussed.

scholarly journals Indentation Tests to Investigate Ice Pressures on Vertical Piers

1977 ◽  
Vol 19 (81) ◽  
pp. 301-312 ◽  
Author(s):  
K. R. Croasdale ◽  
N. R. Morgenstern ◽  
J. B. Nuttall
Keyword(s):  
Strain Rate ◽  
Failure Modes ◽  
Field Tests ◽  
Small Scale ◽  
Initial Contact ◽  
Lake Ice ◽  
Indentation Tests ◽  
Ice Strength ◽  
Unconfined Strength ◽  
The Relationship

AbstractControlled field and laboratory tests were performed to investigate the relationship between ice strength and the maximum ice pressures on vertical piers. The apparatus used in the field tests consisted of a flat indentor (75 cm wide) which was pushed through the ice by hydraulic rams. 27 tests were conducted on lake ice up to one metre thick. Ice pressures in the range 2.5 to 5.0 MPa were obtained for ice in good initial contact with the indentor. The ice pressures exhibited little sensitivity to variations in temperature, ice thickness and strain-rate for the range 7.5 × 10-7 to 4.4 × 10-3 s-1.The average unconfined compressive strengths obtained in the laboratory were about 20% higher than the average field ice pressures. In addition, the laboratory strengths were found to be sensitive to temperature, and to strain-rate in the range 1 × 10-7 to 1 × 10-3 s-1. The confined compressive strength was two to three times the unconfined strength.The failure modes observed in the indentation tests were similar to those predicted (before the tests) by an upper-bound plasticity model. The ability of the model to relate small-scale ice strength to field ice pressures is discussed.

scholarly journals Investigation on the Reflection Coefficient for Seawalls Protected by a Rubble Mound Structure

2021 ◽  
Vol 9 (9) ◽  
pp. 937
Author(s):  
Luigi Pratola ◽  
Antonio Rinaldi ◽  
Matteo Gianluca Molfetta ◽  
Maria Francesca Bruno ◽  
Davide Pasquali ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Wave Reflection ◽  
Experimental Tests ◽  
Coastal Protection ◽  
Empirical Formulas ◽  
New Approach ◽  
Wave Flume ◽  
Mound Structure ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Sea wave reflection from coastal protection structures is one of the main issues in the coastal design process. Several empirical formulas have been proposed so far to predict reflection coefficient from rubble mound breakwaters and smooth slopes. The aim of this study is to investigate wave reflection from a rubble mound structure placed in front of a vertical concrete seawall. Several experimental tests were performed on a two-dimensional wave flume by reproducing on a rubble mound structure with a steep single primary layer armored with a novel artificial unit. A new approach for the prediction of the reflection coefficient based on dimensional analysis is also proposed, and a new empirical equation is derived. The performance of the proposed equation was compared with widespread existing formulas, and a good accuracy was found.

Probabilistic Risk Evaluation for Overall Stability of Composite Caisson Breakwaters in Korea

2020 ◽  
Vol 8 (3) ◽  
pp. 148
Author(s):  
Nhu Son Doan ◽  
Jungwon Huh ◽  
Van Ha Mac ◽  
Dongwook Kim ◽  
Kiseok Kwak
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Skewed Distribution ◽  
Resistance Force ◽  
First Order ◽  
Reliability Method ◽  
Overall Stability ◽  
Rubble Mound

In the present study, the overall stability of typical Korean composite caisson breakwaters that were initially designed following the conventional deterministic approach is investigated using reliability approaches. Therefore, the sensitivity of critical uncertainties regarding breakwater safety is analyzed. Uncertainty sources related to the structure, ocean conditions, and properties of the subsoil and rubble mound are considered in the reliability analysis. Sliding and overturning failures are presented as explicit equations, and three reliability methods, i.e., the mean value first-order second-moment, first-order reliability method, and Monte Carlo simulation, are applied in the evaluation process. Furthermore, the bearing capacity of the rubble mound and subsoil are analyzed using the discrete slice method conjugated with the Monte Carlo simulation. The results of this study establish that the sliding failure generally is the most frequent failure occurring among the above-mentioned overall stability failures (around 15 times more common than failures observed in the foundation). Additionally, it is found that the horizontal wave force primarily contributes to the sliding of the caisson body, whereas the friction coefficient is the main factor producing the resistance force. Furthermore, a much small probability of overturning failure implies that the overturning of a caisson around its heels uncommonly occurs during their lifetime, unlike other overall failure modes. Moreover, the failure in foundations may commonly encounter in the breakwater that has a high rubble mound structure compared with sliding mode. Particularly, the performance function of the all foundation bearing capacities presents a nonlinear behavior and positively skewed distribution when using the Monte Carlo simulation method. This phenomenon proves that simulation methods might be an appropriate approach to evaluate the bearing capacity of a breakwater foundation that can overcome several drawbacks of the conventional design approach.

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