Analysis of vehicle path tracking ability and lateral stability on a floating bridge under a crosswind

The reconstructed route E39 along the west coast of Norway will provide efficient local and regional transportation for people and goods. Efficient transportation implies safety measures exist, e.g., driving speed limits for adverse weather\ua0condition. This is especially important for structures in open areas, such as long-span bridges. This paper investigates the path tracking ability and lateral stability of two vehicle types – a tractor-semitrailer (TS) and a sport utility vehicle (SUV) – on the Bj\uf8rnafjorden floating bridge considering a 1-year storm\ua0condition. At a speed of 108 km/h, the TS experiences a roll-over risk, and at a speed of 90 km/h, it frequently leaves the traffic lane. At the highest speed, the SUV wheels do not lose contact with the bridge deck, but the vehicle does leave the traffic lane. This implies that a TS driver requires more vehicle handling effort over the floating bridge than an SUV driver. Results suggest that a TS can safely enter the bridge at a low speed (36 km/h) and then accelerate to 72 km/h after travelling 2 km. An SUV entering at a speed of 90 km/h and accelerating to 108 km/h after travelling 0.5 km was found to be safe

Investigation of seat suspensions with embedded negative stiffness elements for isolating bus users’ whole-body vibrations

Bus drivers are a group at risk of often suffering from musculoskeletal problems, such as low-back pain, while bus passengers on the last-row seats experience accelerations of high values. In this paper, the contribution of K-seat in decreasing the above concern is investigated with a detailed simulation study. The K-seat model, a seat with a suspension that functions according to the KDamper concept, which combines a negative stiffness element with a passive one, is benchmarked against the conventional passive seat (PS) in terms of comfort when applied to different bus users’ seats. More specifically, it is tested in the driver’s and two different passengers’ seats, one from the rear overhang and one from the middle part. For the benchmark shake, both are optimized by applying excitations that correspond to real intercity bus floor responses when it drives over a real road profile. Then a human model is placed on the seats in order to compare their optimum solutions in terms of the user’s whole-body vibrations (WBVs), using objective comfort metrics. Based on the results, the K-seat improves significantly the comfort of the users (~92%) compared to the PS, while it achieves a similar decrease in the maximum values of the user’s back accelerations (~97%)

Methods to introduce floating bridge motion and wind excitation on a model for the investigation of heavy vehicle dynamics

The proposed floating bridge solution at Bj\uf8rnafjorden in connection with the E39 infrastructure upgrade is an enabler to realize efficient transportation. This bridge and the vehicles shuttling on it will be exposed to inclement weather conditions. The waves and wind excite the floating bridge to induce compound motion in addition to the aerodynamic crosswinds directly interacting with the vehicles. Methods to introduce the complex motion of the floating bridge (multi-post test rig) and aerodynamic crosswinds on a tractor semi-trailer have been established and presented in this paper. The environment-vehicle-driver system is enabled through a co-simulation between MATLAB/Simulink (primary) and Adams (secondary). This complex interplay is studied on the intricate 627-DoF Adams vehicle model coupled with the Adams driver model. Numerical simulations are performed for multiple constant vehicle speeds under laden condition on a road with friction of 0.7 for the 1-year storm weather condition. Vehicle stability and safety assessments such as lane violation, path following ability, rollover risk, and lateral side slip limit are evaluated to draw inferences. Subsequently, permissible vehicle speed for a laden tractor semi-trailer to operate on the floating bridge is suggested. Furthermore, a simpler 9-DoF tractor semi-trailer vehicle model developed in MATLAB/Simulink combined with the pure pursuit tracking based driver model is compared with the Adams model under identical environmental conditions for an unladen case. The simpler vehicle-driver model is validated against the detailed Adams vehicle-driver model through numerical simulations for different constant vehicle speeds

Preoperative Endovascular Embolisation of the Symptomatic Hemangioma in 7th Thoracic Vertebrae: Case Report

Although, as asymptomatic, they appear in about 10-12% of the worldwide population, vertebrae hemangiomas are symptomatic in about 0.9-1.2% of all the cases

Effect of floating bridge motion on vehicle ride comfort and road grip

The aim of this paper is to investigate the influence of floating bridge motion on bus driver’s ride comfort and road grip for the straight concept solution across Bj\uf8rnafjorden. For this investigation 3 degrees of freedom (DOF) bus model is defined for numerical simulation. Bus model has been excited by vertical motion of the bridge for four different bus speeds. Ride comfort has been assessed according to method and criteria proposed by International ISO 2631/1997 standard. For road grip assessing Dynamic Load Coefficient (DLC) has been used. It has been concluded that on floating bridge ‘little uncomfortable’ ISO 2631 criteria is reached at lower bus speed comparing to stationary ground road. Higher values of DLC for the case of floating bridge points out higher variation in vertical tyre forces (worse road grip). For bus speed at 90\ua0km/h, DLC for floating bridge is approximately 0.08 which is 7% higher value comparing it to the case of stationary road

Dynamic amplification factor of multi-span simply supported beam bridge under traffic flow

Simply supported bridges occupy the majority of bridges. Compared with the flexible large span bridges, Dynamic Amplification Factor (DAF) of them is relatively large and attracts lots of studies. However, most of these studies are focused on the simplified condition that a single vehicle passes through a single span bridge. In general, the bridge bears complex traffic flow rather than a single vehicle. The vehicle type and dynamic loads on the bridge are thus dispersed. It is necessary to explore the multi-vehicle effects on the DAF caused by the complex traffic flow. Also, adjacent spans of a multi-span simply supported beam bridge may have continuous dynamic effects on the vehicles. In this regard, the DAF of a simply supported bridge considering the multi-vehicle and multi-span effects are explored numerically based on the coupling dynamic analysis of traffic flow and bridge, which can also consider the acceleration and deceleration of the vehicles. Cellular Automata (CA) method is used to simulate the traffic flow. It is found that the worse the driving condition of the road roughness, the greater the DAF. When road roughness is Class C, the DAF exceeds the values of American and Chinese codes. Under the action of traffic flow, DAF of the first span of the multi-span simply supported beam is larger than that of the span under the single vehicle. Only considering the effect of a single vehicle may underestimate the dynamic impact on the bridge. Sparse traffic flow has a larger DAF than moderate traffic flow and dense traffic flow in the statistic meaning of the multi-span, because the driving speed of sparse traffic flow is closer to the resonant speed of the bridge and the vibration disharmony of multi-vehicles is smaller. The greater the deceleration of the traffic, the greater the dynamic impact on the bridge