Circular Ramp Research Articles

Effects of slope topography on rock avalanche mobility and deposition: A 2-D discrete element method investigation

The impact of rock avalanches is a major concern in mountain areas. However, fundamental understanding and reliable prediction of the depositional area of rock avalanches remains inadequate. Here, an idealized numerical study of granular materials flowing down a slope is carried out using two-dimensional (2-D) discrete element method simulations. The effects of the slope geometry on the mobility and deposit morphology of the granular flow are studied in detail. It is found that the granular flow mobility increases with the curvature radius of the circular ramp, leading to a longer runout distance, which is explained from the viewpoint of energy transfer and dissipation. The results are expected to enhance understanding of the travel and deposition mechanisms of rock avalanches and other related geophysical flows.

Unified Navigational Approach for an Autonomous Vehicle Joining a Multilane Highway from Ramp

Navigating an autonomous vehicle through a circular ramp to join a multilane highway having high-density traffic is a very challenging task. Occupant and vehicle safety are the major considerations while establishing merging scenarios. This article proposes and experimentally implements safe and tactical navigational procedures for merging and leaving the highway scenario using the rendezvous guidance (RG) technique and its modified form. Test scenarios have been established for navigating AVs to merge and leave the highway on a multilane highway with or without the presence of any other vehicle in the zone. In addition, the navigation with enhanced performance of the modified RG algorithm is also established and compared to the conventional RG algorithm. The results indicate that time is reduced considerably by using the modified RG technique. The experimental and simulation results are compared, and their results are the same.

Forming overlapping of circular ramps with flat slabs

Circular ramps for use in multi-storey parking garages are described. The possibility of using flat slabs to form overlapping of circular ramps is analyzed. The layout of flat slabs of circular single-track ramps is completed on one floor (turn). The strength and deformability of one flat slab are calculated. The reinforcement and the drawings of the necessary structural reinforcement of the flat slab are made to form the overlap of the circular ramp

Experimental Study on Overtopping Performance of a Circular Ramp Wave Energy Converter

One of the most important debates on energy is planning for the best carriers in each region and determined based on each country's energy basket. The importance of preserving fossil resources becomes evident when we made the prediction. Iran's oil and gas resources will finish up to 136 years to 79 years. Since the clean energy production is a new source in interested field of researchers. Here we study the performance of overtopping with a circular ramp which can be used as a model of wave energy converter.

Experimental study on overtopping performance of a circular ramp wave energy converter

Circular ramp overtopping wave energy converter (CROWN) is an offshore overtopping wave energy converter that consists of a reservoir surrounded by a circular ramp and an outflow duct installed with a low water head turbine. Physical model experiments were conducted in a wave tank as a preliminary study at Ocean University of China. The wave overtopping behaviors demonstrated that guide vanes can effectively lead the wave water motion on the ramp for overtopping into the reservoir. An analysis of the overtopping discharge shows that the resonant zone is located in the smaller relative wave length domain. Within the scope of shape parameters used in this study, guide vanes and milder ramp slopes were found to significantly enhance the overtopping discharge. The orientation of the guide vane angle also had a large influence on the overtopping flow rates for smaller relative wave heights and lengths. The experimental results are presented with the aim of designing and optimizing the shape parameters of CROWN for a future prototype device.

An Experimental Study on the Effects of Biaxial Bending due to Eccentric Load on RC Beam

Eccentric loads are very common in structures due to building configuration. Unequal slab length, circular ramp, large cantilevers are very common in modern architecture. The RC beams in previous studies were tested under the three and four point uniform loads. Therefore, a simple testing setup was arranged to understand the behaviour of RC beam under eccentric load applied at mid span. In this study the single point load applied eccentrically on RC beam. The beams were tested at different eccentricity and compared with control beam tested under the uniform load or zero eccentricity. Results have shown a drastically reduced crack load up to 54% compared to control beam as the eccentricity increased. However, small changed in ultimate load carrying capacity was observed up to 60mm eccentricity. Eccentric load caused biaxial bending due to high concentration of load on one side of beam, which change failure mode of RC beam from ductile to brittle.

3D Numerical Investigation on Reservoir System for an Overtopping Wave Energy Convertor

Overtopping Wave Energy Convertor (OWEC) is an offshore wave energy convertor, which comprises the circular ramp and reservoir. It collects the overtopped waves and converting water pressure head into electric power through the hydro-turbines installed in the vertical duct, which is fixed in the sea bed. The performance of OWEC can be represented by the operating water heads of the device, which depends on the amount of the wave water overtopping into the reservoir. In the present paper, the reservoir with the duct connecting to the sea water are studied in the 3D numerical wave tank, which has been developed based on the computational fluid dynamics software Fluent 6.3. Both the overtopping motion and the discharges of the reservoir are investigated together, and several shape parameters and incident wave conditions are varied to demonstrate their effects on the performance of OWEC.

Numerical simulation of separated flows in channels

The work deals with numerical modelling of turbulent flows in channels with an expansion of the cross-section where flow separation and reattachment occur. The performance of several eddy viscosity models and an explicit algebraic Reynolds stress model (EARSM) is studied. The used test cases are flows in channels with various backward facing steps where the step is perpendicular or inclined and the top wall is parallel or deflected. Furthermore, a channel with the circular ramp is considered. The numerical solution is achieved by the finite volume method or by the finite element method. The results of both numerical approaches are compared.

Lessons Learned from the Damaged Huilan Interchange in the 2008 Wenchuan Earthquake

A disastrous earthquake struck Wenchuan in China’s Sichuan province in 2008 and caused heavy casualties and structural damage to bridges and buildings. One of the two severely earthquake-damaged curved bridges in China, the Huilan interchange, had been carefully studied, including postearthquake investigation and identification of the cause of failure for this bridge. The Huilan interchange, constructed in 2004 in Mianzhu City, consisted of a viaduct and four horizontally circular ramp bridges with continuous box girders. Field investigations found that the seismic damage to the ramp bridges was especially heavy, one or two short piers in all, but one of the ramp bridges experienced severe failure, and the box girders over the failed piers were fractured. Other piers of the ramp bridges suffered minor-to-moderate damage, including concrete cover spalling, concrete cracking, and slippage damage of the rubber bearings. The viaduct suffered only slight damage, including slippage damage of the rubber bearings and pounding damage of the superstructure. The seismic performance of the bridge was evaluated by finite-element modeling and compared with field observations. It was found that the bearing on top of the shortest pier, Pier 1, was damaged first. Then, the seismic action was concentrated on the next shortest pier, Pier 2, which had the largest flexural stiffness. Pier 2 first yielded in flexure, and, as the lateral displacement increased, the ultimate response of this pier was dominated by its shear capacity, and it eventually failed in flexure-shear mode.