Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: End stop impact forces are horizontal longitudinal forces imposed by the crane on the end stops.
Both the previous South African loading code SABS 0160:1989 and the current South African
loading code SANS 10160 , classify end stop impact force as an accidental load case , hence they
are not expected to occur within the expected lifetime when the guide lines for crane operation are
strictly adhered to.
In the estimation of end stop impact force, the previous South African loading code SABS
0160:1989 gives two guidelines for estimating the end stop impact force. The first guideline is
simplistic in its approach and it’s based on the assumption that the crane and its supporting
structure act as rigid bodies; hence calculation is based on rigid body mechanics. Literature
reviewed reveals that this is not correct. The second guideline is more explicit in its approach as it
takes into account the crane speed, resilience of the buffers and resilience of the end stops.
The current South African loading code, SANS 10160 gives a better representation of the
dynamics of the crane movement. However, the dynamic factor recommended for the estimation of
end stop impact force is empirical in nature and thus lacks adequate scientific backing.
One of the purposes of this research was to investigate the influence of the stiffness of the crane
bridge on the end stop impact force. This was achieved by conducting a series of FEA simulations
on the double bridge EOHTC fitted with elastomeric buffers. For this set of simulations, the effect of
each influencing parameter on the end stop impact force was investigated, and the maximum end
stop impact force was obtained using a constraint optimization technique. From the results
obtained, comparison was then made with the existing maximum end stop impact force for a single
bridge EOHTC fitted with elastomeric buffers.
Another purpose of this research was to investigate the end stop impact force for an electric
overhead travelling cranes (EOHTC) fitted with hydraulic buffers taking into account the dynamics
involved in the movement of the EOHTC. This was achieved by a series of experimental and
numerical investigation. The numerical investigation was conducted using an existing numerical
model of an EOHTC which captures the crane and its supporting structure as a coupled system.
Finite element analysis (FEA) impact force histories obtained were calibrated to the base
experimental impact force histories. Thereafter, a series of FEA simulations were conducted by changing the parameters which have a substantial effect on the end stop impact forces. This
yielded various maximum impact peaks for various parameters. The maximum impact force was
then mathematical obtained from the FEA impact force histories for a given level of reliability using
a constraint optimization technique. Also, codified end stop impact forces were calculated for the
SABS 0160:1989 and SANS 10160-6:2010. From the results obtained, comparison was made
between the codified end stop impact force and the maximum impact force obtained from the
constraint optimization technique. / AFRIKAANSE OPSOMMING: Ent buffer impak kragte is horisontale kragte wat deur die kraan op die entbuffers aangewend
word. Beide die Suid Afrikaanse las kode SABS 0160:1989 en die voorgestelde Suid Afrikaanse
las kode SANS 10160, klasifisseer die entbuffer impak kragte as ‘n ongeluks las geval, dus word
die kragte nie verwag tydens die verwagte leeftyd van die kraan wanneer die riglyne van die kraan
prosedures streng gevolg word nie.
Volgens die Suid-Afrikaanse las kode SABS 0160:1989 word daar twee riglyne voorgestel om die
entbuffer kragte te bepaal. Die eerste riglyn is ‘n eenvoudige riglyn en word gebaseer op die
aaname dat die kraan en die ondersteunende struktuur as ‘n starre ligame reageer en dus word
die kragte bereken deur star ligaam meganika, alhoewel, uit die literatuur word dit bewys as
inkorrek. Die tweede riglyn is ‘n meer implisiete benadering aangesien dit die kraan snelheid,
elastisiteit van die buffers sowel as die elastisiteit van die end stoppe in ag neem.
SANS 10160-6:2019 gee ‘n beter benadering van die dinamiese beweging van die kraan. Die
voorgestelde dinamiese faktor waarmee die ent_buffer_kragte bereken word, is empiries van
natuur .
Een van die doelstellings vir die navorsings projek was om te bepaal wat die invloed van die kraan
brug se styfheid op die entbuffer kragte is. ‘n Aantal Eindige Element Analise (FEA) simulasies is
uitgevoer op ‘n dubbel brug elektriese aangedrewe oorhoofse kraan met elastomeriese buffers.
Van die stel FEA simulasies kan die invloed van elke parameter op die entbuffer impak_kragte
bepaal word. Die maksimum entbuffer impak_kragte is bepaal met behulp van ‘n beperking
optimiserings tegniek. Vanaf hierdie resultate is ‘n vergelyking gemaak met die bestaande
maksimum ent_buffer impak_kragte vir ‘n enkel brug elektriese oorhoofse aangdrewe kraan met
elastomeriese buffers.
‘n Tweede doel rede vir die navorsing was om te bepaal wat die ent buffer impak_kragte op ‘n
elektriese aangedrewe oorhoofse kraan met hidrouliese buffers is. Dit is bepaal deur ‘n aantal
eksperimentele en numeriese toetse uit te voer. Die numeriese toetse is uitgevoer deur gebruik te
maak van ‘n huidige numeriese model van ‘n elektriese aangedrewe oorhoofse kraan wat die
kraan en die ondersteunende struktuur as ‘n.
Die Eindige Element Analise impak_kragte is gekalibreer teen die eksperimenteel bepaalde
impak- kragte. Daarna is ‘n reeks Eindige Element Analise simulasies uitgevoer en sodoende die
parameters te verander wat die mees beduidende invloed op die end stop impak_kragte het. Dit
het verskeie impak_krag pieke vir verskillende parameters meegebring. Die maksimum impak kragte is bepaal van die impak kragte van die Eindige Element Analise vir ‘n gegewe vlak van
betroubaarheid deur gebruik te maak van die beperking optimiserings tegniek. Daarmee saam is
die gekodifiseerde ent buffer impak kragte bereken volgen SABS 0160:1989 en die SANS 10160-
6:2010. Vanaf hierdie resultate is ‘n vergelyking gemaak tussen die gekodifiseerde entbuffer
impak_kragte en die maksimum impak_kragte wat bepaal is deur die (beperking optimiserings
tegniek).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5399 |
| Date | 12 1900 |
| Creators | Idowu,Ifeolu Mobolaji |
| Contributors | Haas, T. N., University of Stellenbosch. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 139 p. : ill. |
| Rights | University of Stellenbosch |
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