Vragrangskikkings ter voorkoming van asmassalasgrens-oorskryding deur padkarweiers in Suid-Afrika

Jacobs, Cornelius Gregorius (Stellenbosch : Stellenbosch University, 2012-03)

Thesis

ENGLISH ABSTRACT: Road Tra c legislation prescribes constraints on the forces/loads which vehicles may exert on the road at contact surfaces or load points. These constraints have bearing on speci c contact surfaces or groups of contact surfaces. The constraints are in the form of maximum force values and maximum ratios, which may exist between forces. The forces exerted by a vehicle on the road is determined by a combination of the vehicle's own mass, dimensional characteristics, and the mass and position of its cargo. The mass and position of the cargo can be modelled by only considering its centroid. The centroid's position is linked to a certain cargo arrangement. It is necessary, in terms of legal constraints, to distinguish between legally permissable- and non-permissable arrangements. Methods are proposed in this dissertation to determine the borders for the position of the centroid according to cargo-mass, for a variety of vehicle con gurations. The determination of borders for the position of the centroid is the result of a three part process. Firstly, the legal limits are translated to mathematical inequalities that must be satis ed for the forces at contact surfaces. Secondly, conservative parametric estimates for the forces, in terms of the position and the mass of the centroid of a given vehicle, must be derived. Finally these estimates are incorporated into the load constraints and an enclosed permissable area for the centroid is found. These position constraints are suitable inputs to solution methods of various cargo arrangement problems. Linear programmes which can solve certain general arrangement problems by utilising the position constraints on the centroid, were successfully developed. Solutions are presented for the arrangement of pallet-freight, as well as the arrangement of cargo units with asymetrical centroids over the length or width of a vehicle's cargo area.

AFRIKAANSE OPSOMMING: Padvervoerwetgewing skryf grense op kragte/laste voor wat voertuie by kontakoppervlakke of laspunte, op die pad mag uitoefen. Hierdie voorskrifte het betrekking op spesi eke laspunte en groepe van laspunte. Die voorskrifte is in die vorm van maksimum laswaardes by laspunte en maksimum ratio's wat tussen sekere laste mag bestaan. Die laste wat 'n voertuig op die pad uitvoer word bepaal deur 'n kombinasie van die voertuig se eie massa, dimensionele eienskappe, sowel as sy vrag se massa en posisie. Die vrag se massa en posisie kan gemodelleer word deur slegs die massamiddelpunt daarvan te beskou. Die massamiddelpunt se posisie word gekoppel aan 'n bepaalde vragrangskikking. Dit is nodig om, in terme van wetlike voorskrifte, te kan onderskei tussen wetlik toelaatbare en -ontoelaatbare rangskikkings. Metodes word in hierdie proefskrif voorgestel waarmee daar grense vir die posisie van die vragmassamiddelpunt bepaal kan word na gelang van die vragmassa, vir 'n verskeidenheid van voertuigkon gurasies. Die bepaling van grense vir die posisie van die vragmassamiddelpunt is die resultaat van 'n drieledige proses. Eerstens word die wetlike beperkings herlei na wiskundige ongelykhede waarbinne laste by kontakoppervlakke moet val. Tweedens word konserwatiewe parametriese beramings vir die laste verkry in terme van die ligging en massa van die vragmassamiddelpunt vir 'n gegewe voertuig. Laastens word hierdie beramings in die lasbeperkings opgeneem om 'n afgebakende toelaatbare gebied vir die vragmassamiddelpunt se posisie te verkry. Hierdie posisiebeperkings is geskik om as inset te dien in die oplossingmetodes van 'n verskeidenheid van vragrangskikkingsprobleme. Line^ere programme wat sekere algemene rangskikkingsprobleme kan oplos deur die aanwending van posisiebeperkings op die vragmassamiddelpunt, is suksesvol ontwikkel. Oplossings word aangebied vir die rangskikking van paletvrag, asook die rangskikking van vrageenhede met asimmetriese massamiddelpunte oor die lengte of breedte van 'n voertuig se vragarea.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/19948
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