scholarly journals Experimental measurements of flood-induced impact forces on exposed elements

2018 ◽  
Vol 40 ◽  
pp. 05005 ◽  
Author(s):  
Michael Sturm ◽  
Bernhard Gems ◽  
Florian Keller ◽  
Bruno Mazzorana ◽  
Sven Fuchs ◽  
...  
Keyword(s):  
Force Measurement ◽  
Flow Patterns ◽  
Building Envelope ◽  
Alluvial Fan ◽  
Scale Model ◽  
Experimental Measurements ◽  
Alluvial Fans ◽  
Flood Hazards ◽  
Impact Forces ◽  
The Impact

Torrential flood hazards are a major threat for inhabited alluvial fans. They have the potential to relocate large amounts of sediment from the upper catchments to settlement areas on the alluvial fans where typically distributary processes take place. The approaching water-sediment-mixture impacting on building walls are part of a set of damage-generating mechanisms and may cause severe damages to buildings and infrastructure. It is difficult to predict the magnitude and temporal forces on buildings due to the complex flow patterns and sediment deposition processes around obstacles on the floodplain. Our work focuses on experimental measurements of impact forces of flood events on buildings at a 1:30 scale model. It covers the alluvial fan of the Schnannerbach torrent (Austria) with a set of building structures which are equipped with force measurement devices. The measured impact forces are correlated to the approaching flow heights. Influencing factors on the impacts forces such as surrounding buildings on the floodplain and the presence of openings in the building envelope are also analysed. The influence of different hydraulic flow patterns on the impact forces and regression analyses for an estimation of impact forces are presented.

scholarly journals Interactions between channels and tributary alluvial fans: channel adjustments and sediment-signal propagation

2019 ◽  
Author(s):  
Sara Savi ◽  
Stefanie Tofelde ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Signal Propagation ◽  
Main Channel ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial System ◽  
Channel Network ◽  
Fluvial Deposits ◽  
The Impact

Abstract. Climate and tectonics impact water and sediment fluxes to fluvial systems. These boundary conditions set river form and can be recorded by fluvial deposits. Reconstructions of boundary conditions from these deposits, however, is complicated by complex channel-network interactions and associated sediment storage and release through the fluvial system. To address this challenge, we used a physical experiment to study the interplay between a main channel and a tributary under different forcing conditions. In particular, we investigated the impact of a single tributary junction, where sediment supply from the tributary can produce an alluvial fan, on channel geometries and associated sediment-transfer dynamics. We found that the presence of an alluvial fan may promote or prevent sediment to be moved within the fluvial system, creating different coupling conditions. A prograding alluvial fan, for example, has the potential to disrupt the sedimentary signal propagating downstream through the confluence zone. By analyzing different environmental scenarios, our results indicate the contribution of the two sub-systems to fluvial deposits, both upstream and downstream of the tributary junction, which may be diagnostic of a perturbation affecting the tributary or the main channel only. We summarize all findings in a new conceptual framework that illustrates the possible interactions between tributary alluvial fans and a main channel under different environmental conditions. This framework provides a better understanding of the composition and architecture of fluvial sedimentary deposits found at confluence zones, which is essential for a correct reconstruction of the climatic or tectonic history of a basin.

Experimental Study of Air Gap Response and Wave Impact Forces of a Semi-Submersible Drilling Unit

2006 ◽  
Author(s):  
Saeid Kazemi ◽  
Atilla Incecik
Keyword(s):  
Experimental Study ◽  
Offshore Structures ◽  
Model Tests ◽  
Air Gap ◽  
Scale Model ◽  
Offshore Structure ◽  
The Caspian Sea ◽  
Wave Impact ◽  
Impact Forces ◽  
The Impact

An experimental study for predicting the air gap and potential deck impact of a floating offshore structure is the main topic of this research. Numerical modeling for air gap prediction is particularly complicated in the case of floating offshore structures because of their large volume, and the resulting effects of wave diffraction and radiation. Therefore, for new floating platforms, the model tests are often performed as part of their design process. This paper summarizes physical model tests conducted on a semi-submersible model, representing a 1-to-100 scale model of a GVA4000 class, “IRAN-ALBORZ”, the largest semi-submersible platform in the Caspian Sea, under construction in North of Iran, to evaluate the platform’s air gap at different locations of its deck and also measure the impact forces in case of having negative air gap. The model was tested in regular waves in the wave tank of Newcastle University. The paper discusses the experimental setup, test conditions, and the resulting measurements of the air gap and the wave impact forces by using eight wave probes and three load cells located at different points of the lower deck of the platform.

scholarly journals RESPONSE OF SEADYKES DUE TO WAVE IMPACTS

1976 ◽  
Vol 1 (15) ◽  
pp. 149 ◽  
Author(s):  
A. Fuhrboter ◽  
H.H. Dette ◽  
J. Grune
Keyword(s):  
Laboratory Data ◽  
Breaking Waves ◽  
Scale Model ◽  
Small Scale ◽  
Air Entrapment ◽  
Small Areas ◽  
Impact Forces ◽  
The Stability ◽  
Short Time ◽  
The Impact

Damages on seadykes and revetments are mainly caused by wave impacts due to breaking waves. These impact forces act on small areas for a very short time and cause crater-like formations, when the forces are transmitted instantaneously to the side-walls of cracks in the cover of dykes or through joints into and below revetments. In this paper the results of investigations on impact forces are presented. A comparison of field data and laboratory data proves considerable differences, which must be explained mainly by the different air entrapment for prototype and small-scale conditions in the breaking waves. Both the data from field and small-scale model emphasize, that the slope of the dyke or revetment is responsible at first for frequency and magnitude of the impact forces. Furthermore the effect of impact forces is demonstrated by the results of investigations on the stability of stone revetments with joints.

scholarly journals 3D-hydrodynamic modelling of flood impacts on a building and indoor flooding processes

2016 ◽  
Author(s):  
B. Gems ◽  
B. Mazzorana ◽  
T. Hofer ◽  
M. Sturm ◽  
R. Gabl ◽  
...  
Keyword(s):  
Risk Management ◽  
Numerical Modelling ◽  
Vulnerability Assessment ◽  
Flood Risk ◽  
Pure Water ◽  
Flood Plain ◽  
Flood Risk Management ◽  
Building Envelope ◽  
Flood Hazards ◽  
The Impact

Abstract. Given the current challenges in flood risk management and vulnerability assessment of buildings exposed to flood hazards, three-dimensional numerical modelling of torrential floods and its interaction with buildings are presented. By means of a case study application, the FLOW-3D software is applied to the lower reach of the Rio Vallarsa torrent in the village of Laives (Italy). A single-family house on the flood plain is thereby considered very detailed and exposed to a 300 yr flood hydrograph. Different building representation scenarios, amongst an entire impervious building envelope and the assumption of fully permeable doors, windows and cellar shafts, are analysed. The modelling results give insight into the flooding process of the building’s interior, the impacting hydrodynamic forces on the exterior and interior walls and, further, quantify the impact of flooding a building on the flow field on the adjacent flood plain. The presented study means a step towards the development of a comprehensive physical vulnerability assessment framework. For pure water floods, it shows possibilities and limits of advanced numerical modelling techniques within flood risk management and, thereby, the planning of local structural protection measures.

scholarly journals 3-D hydrodynamic modelling of flood impacts on a building and indoor flooding processes

2016 ◽  
Vol 16 (6) ◽  
pp. 1351-1368 ◽  
Author(s):  
Bernhard Gems ◽  
Bruno Mazzorana ◽  
Thomas Hofer ◽  
Michael Sturm ◽  
Roman Gabl ◽  
...  
Keyword(s):  
Risk Management ◽  
Numerical Modelling ◽  
Vulnerability Assessment ◽  
Flood Risk ◽  
Pure Water ◽  
Flood Plain ◽  
Flood Risk Management ◽  
Building Envelope ◽  
Flood Hazards ◽  
The Impact

Abstract. Given the current challenges in flood risk management and vulnerability assessment of buildings exposed to flood hazards, this study presents three-dimensional numerical modelling of torrential floods and its interaction with buildings. By means of a case study application, the FLOW-3D software is applied to the lower reach of the Rio Vallarsa torrent in the village of Laives (Italy). A single-family house on the flood plain is therefore considered in detail. It is exposed to a 300-year flood hydrograph. Different building representation scenarios, including an entire impervious building envelope and the assumption of fully permeable doors, light shafts and windows, are analysed. The modelling results give insight into the flooding process of the building's interior, the impacting hydrodynamic forces on the exterior and interior walls, and further, they quantify the impact of the flooding of a building on the flow field on the surrounding flood plain. The presented study contributes to the development of a comprehensive physics-based vulnerability assessment framework. For pure water floods, this study presents the possibilities and limits of advanced numerical modelling techniques within flood risk management and, thereby, the planning of local structural protection measures.

scholarly journals Interactions between main channels and tributary alluvial fans: channel adjustments and sediment-signal propagation

2020 ◽  
Vol 8 (2) ◽  
pp. 303-322
Author(s):  
Sara Savi ◽  
Stefanie Tofelde ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Signal Propagation ◽  
Main Channel ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial System ◽  
Channel Network ◽  
Fluvial Deposits ◽  
The Impact

Abstract. Climate and tectonics impact water and sediment fluxes to fluvial systems. These boundary conditions set river form and can be recorded by fluvial deposits. Reconstructions of boundary conditions from these deposits, however, is complicated by complex channel–network interactions and associated sediment storage and release through the fluvial system. To address this challenge, we used a physical experiment to study the interplay between a main channel and a tributary under different forcing conditions. In particular, we investigated the impact of a single tributary junction, where sediment supply from the tributary can produce an alluvial fan, on channel geometries and associated sediment-transfer dynamics. We found that the presence of an alluvial fan may either promote or prevent the movement of sediment within the fluvial system, creating different coupling conditions. By analyzing different environmental scenarios, our results reveal the contribution of both the main channel and the tributary to fluvial deposits upstream and downstream from the tributary junction. We summarize all findings in a new conceptual framework that illustrates the possible interactions between tributary alluvial fans and a main channel under different environmental conditions. This framework provides a better understanding of the composition and architecture of fluvial sedimentary deposits found at confluence zones, which can facilitate the reconstruction of the climatic or tectonic history of a basin.

Condition for incision of alluvial fan in an experimental coupled catchment-fan geomorphic system forced by oscillatory precipitation

2020 ◽  
Author(s):  
Stephane Bonnet ◽  
Valeria Zavala Ortiz ◽  
Sébastien Carretier
Keyword(s):  
Extreme Values ◽  
Laser Sheet ◽  
Sediment Concentration ◽  
Alluvial Fan ◽  
Rainfall Rate ◽  
Mountain Range ◽  
Alluvial Fans ◽  
Alluvial Deposits ◽  
The Mean ◽  
The Impact

<p>Alluvial fans are cone-shaped bodies of alluvial deposits accumulated along mountain range fronts at the outlet of catchments. They represent valuable archives of mass transfer in their feeding catchment and can potentially be used to infer the impact of tectonic and climatic variations on erosion and landscapes, because of the influence of these factors on the sediment and water fluxes coming from the upstream catchment. Although a transition from aggradation to incision is observed in many natural alluvial fans, the conditions driving such change remain unclear. We investigate this problem here through a laboratory-scale approach where eroded materials from an uplifting mountain may deposit on a plateau, erosion being driven by the surface runoff of water from an artificial rainfall device. We consider here results from 8 experiments, 700 to 900 minutes-long, performed with the same uplift rate but with different sequences of variations of the rainfall rate (10 to 40 minutes-long) between two extreme values. The topography was digitized every 10 minutes thanks to a high-resolution laser sheet.</p><p>We observe that the mean slope of the alluvial fans is inversely proportional to the mean rainfall rate on the mountain and that the denudation rate of the uplifting landscape varies in phase with the cyclic variations of rainfall. Because catchments are out of equilibrium (denudation equals uplift) during most of the time, the sediment (Qs) and water (Qw) fluxes at their outlet continuously vary with time: Qs varying depending on the balance between erosion and uplift, Qs and Qw varying depending on whether the catchments enlarge or shrink. Depending on these conditions, catchments show a variety of trends of Qs vs Qw for a given value of rainfall, Qs increasing or decreasing with Qw, or being independent of Qw. Then for each catchment, oscillations of rainfall drive alternations between two individual Qs vs Qw trends, the slope of these trends being indicative of the sediment concentration in the mini-rivers at the outlet of catchments that feed alluvial fans.</p><p>From the analyze of our whole dataset, we conclude that incision of alluvial fans occurs when rainfall increases and when it goes with a decrease of the Qs/Qw ratio, i.e. with a decrease of concentration at the outlet of the catchment. This control is modulated by the slope of the fan, incision only occurring for fans above a threshold slope. Then, the decrease in sediment concentration required to initiate the incision is weaker for steeper fans and decreases with increasing fan slope.</p><p>Several studies already demonstrated how a decrease of Qs or an increase of Qw drives incision. We show here that these two parameters are coupled and covariate following the dynamical state of catchments. We also demonstrate that the decrease of the Qs/Qw ratio required for initiating the incision of a fan is lower for steeper fans, that is for fans that develop under more arid condition.</p>

scholarly journals Enhancing flood hazard estimation methods on alluvial fans using an integrated hydraulic, geological and geomorphological approach

2018 ◽  
Vol 18 (4) ◽  
pp. 1159-1171 ◽  
Author(s):  
Zeinab Mollaei ◽  
Kamran Davary ◽  
Seyed Majid Hasheminia ◽  
Alireza Faridhosseini ◽  
Yavar Pourmohamad
Keyword(s):  
Flood Hazard ◽  
Cost Effective ◽  
Developed Countries ◽  
The United States ◽  
Alluvial Fan ◽  
Geographical Information ◽  
Estimation Methods ◽  
Alluvial Fans ◽  
Flood Hazards ◽  
2D Model

Abstract. Due to the uncertainty concerning the location of flow paths on active alluvial fans, alluvial fan floods could be more dangerous than riverine floods. The United States Federal Emergency Management Agency (FEMA) used a simple stochastic model named FAN for this purpose, which has been practiced for many years. In the last decade, this model has been criticized as a consequence of development of more complex computer models. This study was conducted on three alluvial fans located in northeast and southeast Iran using a combination of the FAN model, the hydraulic portion of the FLO-2D model, and geomorphological information. Initial stages included three steps: (a) identifying the alluvial fans' landforms, (b) determining the active and inactive areas of alluvial fans, and (c) delineating 100-year flood within these selected areas. This information was used as an input in the mentioned three approaches of the (i) FLO-2D model, (ii) geomorphological method, and (iii) FAN model. Thereafter, the results of each model were obtained and geographical information system (GIS) layers were created and overlaid. Afterwards, using a scoring system, the results were evaluated and compared. The goal of this research was to introduce a simple but effective solution to estimate the flood hazards. It was concluded that the integrated method proposed in this study is superior at projecting alluvial fan flood hazards with minimum required input data, simplicity, and affordability, which are considered the primary goals of such comprehensive studies. These advantages are more highlighted in underdeveloped and developing countries, which may well lack detailed data and financially cannot support such costly projects. Furthermore, such a highly cost-effective method could be greatly advantageous and pragmatic for developed countries.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

scholarly journals Soft-drop grooming for hadronic event shapes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Jeremy Baron ◽  
Daniel Reichelt ◽  
Steffen Schumann ◽  
Niklas Schwanemann ◽  
Vincent Theeuwes
Keyword(s):  
Event Generator ◽  
Experimental Measurements ◽  
Event Shape ◽  
Matrix Elements ◽  
Underlying Event ◽  
Hadronic Event ◽  
Wide Range ◽  
Event Shapes ◽  
The Impact ◽  
Perturbative Corrections

Abstract Soft-drop grooming of hadron-collision final states has the potential to significantly reduce the impact of non-perturbative corrections, and in particular the underlying-event contribution. This eventually will enable a more direct comparison of accurate perturbative predictions with experimental measurements. In this study we consider soft-drop groomed dijet event shapes. We derive general results needed to perform the resummation of suitable event-shape variables to next-to-leading logarithmic (NLL) accuracy matched to exact next-to-leading order (NLO) QCD matrix elements. We compile predictions for the transverse-thrust shape accurate to NLO + NLL′ using the implementation of the Caesar formalism in the Sherpa event generator framework. We complement this by state-of-the-art parton- and hadron-level predictions based on NLO QCD matrix elements matched with parton showers. We explore the potential to mitigate non-perturbative corrections for particle-level and track-based measurements of transverse thrust by considering a wide range of soft-drop parameters. We find that soft-drop grooming indeed is very efficient in removing the underlying event. This motivates future experimental measurements to be compared to precise QCD predictions and employed to constrain non-perturbative models in Monte-Carlo simulations.

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