Risikoanalyse ved investeringer i eiendomsutvikling

Masteroppgave i industriell økonomi og teknologiledelse IND590 2013 – Universitetet i Agder, GrimstadBeslutningstagning under usikkerhet er et bredt emne som er relevant i de fleste bedrifter og bransjer. Denne oppgaven søker å beskrive hvilke usikkerheter som ligger i eiendomsutvikling hos bedriften Myrvoll Bolig AS. Hensikten med oppgaven har vært å utarbeide et verktøy som kan benyttes til beslutningstagning. Ved å benytte observasjoner fra tidligere prosjekter prøver oppgaven å beskrive hvilke usikkerheter som ligger i bedriftens fremtidige byggeprosjekter. Til dette er det laget to simuleringsmodeller som har utgangspunkt i monte carlo metoden. Det er benyttet to forskjellige teknikker til oppbygning av modell. Modellene er prøvd på to aktuelle tomteområder som bedriften vurderer å kjøpe i løpet av høsten 2013. Begge tomteområdene befinner seg i Ås kommune i Akershus og ligger omtrent 1 km fra hverandre. Tomteområdene er forskjellige i størrelse, utnyttelsesgrad, og begge tomteområdene er delt opp i flere byggefelt. I tillegg er tidsaspektet for gjennomføring av de to prosjektene forskjellige. Modellene prøver å beskrive usikkerheten som ligger i de samlede byggekostnadene til et byggefelt. Ved å benytte trippelestimater fra et utvalg eiendomsmeglere er det gjort et forsøk på å beskrive utviklingen i boligprisene. Modellen kommer deretter med en anbefaling til en øvre grenseverdi hvor hva bedriften skal være villig til å betale for tomteområdene. I tillegg er det gjort en følsomhetsanalyse på de forskjellige byggekostnadene som finnes i en prosjektgjennomføring

Effects of wind loads and floating bridge motion on intercity bus lateral stability

Efficient transportation is an important factor for regional socio-economic growth. Excitations from wind loads and road motions can influence vehicle-driver behaviour in a way that may impair transportation. This is especially true in open areas such as long-span bridges. This paper investigates the influence of wind loads and floating bridge motions on bus lateral stability for the straight concept solution across Bj\uf8rnafjorden in Norway. For thisinvestigation, an 8-degree-of-freedom model of a two-axle coach is used. The defined driver model is based on the pure pursuit path tracking method. The vehicle deviation from the path is found to increase with increasing bus speed. This deviation is significant after the vehicle enters the bridge (e.g., over 0.5 m for a speed of 90 km/h). At 108 km/h, the windward rear wheel loses contact, indicating the potential risk of vehicle roll-over. The mean androot-mean-square values of the handwheel steering angle increase with increasing speed, which might cause difficulty for the driver to control the vehicle. Simulation results suggest that the bus can suitably enter the bridge at a lower speed (e.g., 72 km/h) with the possibility of increasing the speed (up to 90 km/h) after approximately 2 km of travelled distance

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

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

Dimensjonering og byggemetode av nettverksbru

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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