The ultimate strength assessment of steel tubular members is of the utmost importance to the design and maintenance of many structures including large offshore platforms. Ultimate strength assessments I using numerical solutions must model both nonlinear material and geometric behaviour. The latter must consider large displacements, very often large rotations, and possibly even large strains. These numerical solutions must be computationally efficient and be capable of running on generally available computer hardware, i.e. minicomputers. To achieve this efficiency, attention must be paid to programming considerations, and a new suite of data management modules has been developed and is described in this thesis, which minimise disk storage and speed program development. In addition, the structural modelling was carried out almost exclusively using the Semiiaaf thin shell element. The work described in this thesis considers most of the components which contribute to the numerical ultimate strength analysis of steel tubular members. Theoretically, attention has been focused in two areas, namely the geometric nonlinearity and the automatic solution of the resulting nonlinear equations. A detailed study has been carried out to understand fully the main methods of accounting for geometric nonlinearity from fundamentals of continuum mechanics. The study has considered both the Green-Lagrange and Logarithmic strain measures with a Total Lagrangian, Updated Lagrangian and Eulerian description of motion. These formulations have been included in the Semiiaaf shell element, firstly using a continuum mechanics based approach, and secondly using the more orthodox stress resultant approach. At all stages within the thesis attention is drawn to the effects of the approximations which have been made and their resulting limitations in the respective formulations. The solution of the nonlinear equations is also covered in detail using Newton-type algorithms coupled with line searches. The solution algorithms have been derived for a constrained environment where a modified version of the generalised arc-length constraint has been used. The inclusion of material nonlinearity has been well developed previously but has been included for completeness. To demonstrate the performance and limitations of the theory presented, several carefully chosen numerical examples have been included which include the analysis of tubular steel T and X joints connections and residual strength assessment of a dented pipeline riser. Where possible, results have been compared with experimental tests. The thesis concludes that for general engineering structures, the Total Lagrangian approach based on the stress resultant model gives good engineering results, even in the presence of moderately large rotations. Of the alternative formulations the Updated Lagrangian layered approach is probably the most effective for large rotations and small to moderate strains.

Doctor of Philosophy / The aims of the Thesis were: to investigate and quantify the factors influencing the production of maximum isometric grip strength force in a sample of Australian teenagers when using JamarTM-like handgrip dynamometers; to determine the reliability of this measure over long and short retest intervals; to establish a database of anthropometric and strength values for this group and prediction equations for premorbid strengths to aid assessment of recovery in those with upper limb pathologies. The history of these handgrip dynamometers demonstrates that they have been employed in one form or another for over three hundred years and are still widely used today in hand rehabilitation and medical examinations. Many new types of dynamometers have been constructed subsequent to the ubiquitous JamarTM and have all been briefly reviewed here. Handedness (dominance) was thought to be a possible factor influencing grip strength performance and was later evaluated. But first, the Edinburgh Handedness Inventory was tested with 658 teenagers and 64 adults and confirmed to be a valid tool for assessing handedness. Its validity was improved by substituting the tasks of sweeping and opening the lid of a box for hammering and use of a screwdriver. Its excellent reliability (ICC = .78, p < 0.01) was confirmed with 45 teenagers and 45 adults. There were 235 teenagers who performed maximal isometric grip strength tests and from the results a local database was created. It was confirmed that the grip strength difference in males and females becomes significant after the age of 13 years, and that the average teenaged male is stronger than the average teenaged female by 11.2 Kg force (p < .01). Height, weight, BMI, hand dimensions, past upper limb injuries, degrees of handedness and exercise levels were measured and compared with known norms to establish that the grip strength tested sample of teenagers was representative of urban teenagers in Australia. The influence of handedness on maximal grip strength in dominant and non-dominant hands was unable to be completely ascertained due to the vast majority of the sample of teenagers being right-handed. Only 13 of the 235 teenagers used their left hand for most tasks, with another 20 using their left hands for a small majority of tasks. There was a grip strength bias towards the dominant hand of 2.63 kg force (p < .01). The most accurate way to predict the grip strength of one hand is by knowing the grip strength of the other hand. Prediction models found that 90% (R2 adj .902) and 70% (R2adj .702) of the variance in one hand could be accounted for by the grip strength of their other hand for male and female teenagers, respectively. Prediction equations were also created to assist in estimating the pre-morbid grip strength of teenagers suffering from bilateral hand injuries. If for the males, measurements for height and hand surface area were entered into these models, the grip strength of the dominant and non-dominant hands could be estimated with 62.6 and 63.5% of the variance between the real and predicted scores accounted for, respectively. For the females the prediction models using height and hand surface area could only account for 33.9 and 42.8% of the variances, with no other independent variables improving the prediction equations. The reliability of the maximal grip strength performance of 154 of these teenagers was retested after one or four weeks. A number of sub-group permutations were created for age, gender, retest time interval and handedness groups. The measures of grip strength for males were highly reliable with ICC (3,1) values ranging from .91 to .97. These measures were significantly higher than that obtained from the females, where reliability values ranged from .69 to .83. Handedness played a significant part in grip strength reliability. The dominant hand of right-handed teenagers achieved an ICC (3,1) of .97, as contrasted with the non-dominant hand of left-handers who attained a very poor ICC (3,1) of .27. The shape of the hands of the males did not influence their grip strength or their reliability values, which ranged from .954 to .973. The shape of female hands did not affect their ability to generate maximal grip strength, only its reliability. The females with hands shaped squarer-than-average had mean grip strength reliability values of ICC (3,1) at only .48, in contrast to those with longer-than-average hands who achieved a mean ICC (3,1) of .92. The handle shape of the dynamometer may disadvantage square-handed females, and this should be further investigated.

Doctor of Philosophy / The aims of the Thesis were: to investigate and quantify the factors influencing the production of maximum isometric grip strength force in a sample of Australian teenagers when using JamarTM-like handgrip dynamometers; to determine the reliability of this measure over long and short retest intervals; to establish a database of anthropometric and strength values for this group and prediction equations for premorbid strengths to aid assessment of recovery in those with upper limb pathologies. The history of these handgrip dynamometers demonstrates that they have been employed in one form or another for over three hundred years and are still widely used today in hand rehabilitation and medical examinations. Many new types of dynamometers have been constructed subsequent to the ubiquitous JamarTM and have all been briefly reviewed here. Handedness (dominance) was thought to be a possible factor influencing grip strength performance and was later evaluated. But first, the Edinburgh Handedness Inventory was tested with 658 teenagers and 64 adults and confirmed to be a valid tool for assessing handedness. Its validity was improved by substituting the tasks of sweeping and opening the lid of a box for hammering and use of a screwdriver. Its excellent reliability (ICC = .78, p < 0.01) was confirmed with 45 teenagers and 45 adults. There were 235 teenagers who performed maximal isometric grip strength tests and from the results a local database was created. It was confirmed that the grip strength difference in males and females becomes significant after the age of 13 years, and that the average teenaged male is stronger than the average teenaged female by 11.2 Kg force (p < .01). Height, weight, BMI, hand dimensions, past upper limb injuries, degrees of handedness and exercise levels were measured and compared with known norms to establish that the grip strength tested sample of teenagers was representative of urban teenagers in Australia. The influence of handedness on maximal grip strength in dominant and non-dominant hands was unable to be completely ascertained due to the vast majority of the sample of teenagers being right-handed. Only 13 of the 235 teenagers used their left hand for most tasks, with another 20 using their left hands for a small majority of tasks. There was a grip strength bias towards the dominant hand of 2.63 kg force (p < .01). The most accurate way to predict the grip strength of one hand is by knowing the grip strength of the other hand. Prediction models found that 90% (R2 adj .902) and 70% (R2adj .702) of the variance in one hand could be accounted for by the grip strength of their other hand for male and female teenagers, respectively. Prediction equations were also created to assist in estimating the pre-morbid grip strength of teenagers suffering from bilateral hand injuries. If for the males, measurements for height and hand surface area were entered into these models, the grip strength of the dominant and non-dominant hands could be estimated with 62.6 and 63.5% of the variance between the real and predicted scores accounted for, respectively. For the females the prediction models using height and hand surface area could only account for 33.9 and 42.8% of the variances, with no other independent variables improving the prediction equations. The reliability of the maximal grip strength performance of 154 of these teenagers was retested after one or four weeks. A number of sub-group permutations were created for age, gender, retest time interval and handedness groups. The measures of grip strength for males were highly reliable with ICC (3,1) values ranging from .91 to .97. These measures were significantly higher than that obtained from the females, where reliability values ranged from .69 to .83. Handedness played a significant part in grip strength reliability. The dominant hand of right-handed teenagers achieved an ICC (3,1) of .97, as contrasted with the non-dominant hand of left-handers who attained a very poor ICC (3,1) of .27. The shape of the hands of the males did not influence their grip strength or their reliability values, which ranged from .954 to .973. The shape of female hands did not affect their ability to generate maximal grip strength, only its reliability. The females with hands shaped squarer-than-average had mean grip strength reliability values of ICC (3,1) at only .48, in contrast to those with longer-than-average hands who achieved a mean ICC (3,1) of .92. The handle shape of the dynamometer may disadvantage square-handed females, and this should be further investigated.

Thesis (M.Tech.: Chiropractic)--Durban University of Technology, 2008 / The core stability, club head velocity and ball carry in golfers with and without low back pain – a comparative study. Objective: The aims of this study was to establish whether an observable difference exists in the abdominal core stability of two comparable groups of golfers: one asymptomatic and the other suffering from low back pain, and whether an observable reduction of performance, expressed as club head velocity and ball carry can be observed in those with low back pain. First Objective was to differentiate the groups at baseline with respect to core stability strength between asymptomatic golfers and golfers suffering from low back pain. Whereas the Second Objective was to establish whether a relationship exists between abdominal core stability, CHV and ball carry in the two population groups under study. Following the above the Third Objective was to establish which other factors besides core stability strength have an effect on CHV and ball carry. And lastly the Fourth Objective was to establish the correlation between CHV and ball carry. Design: A comparative study was carried out between the two sample groups. A sample of forty patients were selected for this study, where twenty patients were asymptomatic and had no current episode of low back pain and were able to maintain a core contraction; and the other twenty patients low back pain and could not maintain a core contraction. Because the patients presented in a random manner, the patients were matched as close as possible according to age, so as to have better comparative value between the groups (the maximum age difference of a year was instituted). This allowed for comparisons among similar ages, with the difference being their low back pain and core contraction status. Outcome Measure: Each golfer was required to hit 5 balls using a standard club (in this study, a standard driver was used), after which an average value v was calculated for CHV and ball carry. All measurements were carried out using the Flightscope Pro machine at the Durban Pro Shop. Results: Core stability and low back pain did not influence CHV. However there was a non significant trend which indicated higher ball carry in the group with better core stability and no low back pain than in the group with low back pain and poor core stability. Increasing age and handicap reduced the CHV and ball carry values significantly. Ball carry and CHV were positively correlated together in both groups.

Thesis (M.Tech.: Chiropractic)--Durban University of Technology, 2008 / The core stability, club head velocity and ball carry in golfers with and without low back pain – a comparative study. Objective: The aims of this study was to establish whether an observable difference exists in the abdominal core stability of two comparable groups of golfers: one asymptomatic and the other suffering from low back pain, and whether an observable reduction of performance, expressed as club head velocity and ball carry can be observed in those with low back pain. First Objective was to differentiate the groups at baseline with respect to core stability strength between asymptomatic golfers and golfers suffering from low back pain. Whereas the Second Objective was to establish whether a relationship exists between abdominal core stability, CHV and ball carry in the two population groups under study. Following the above the Third Objective was to establish which other factors besides core stability strength have an effect on CHV and ball carry. And lastly the Fourth Objective was to establish the correlation between CHV and ball carry. Design: A comparative study was carried out between the two sample groups. A sample of forty patients were selected for this study, where twenty patients were asymptomatic and had no current episode of low back pain and were able to maintain a core contraction; and the other twenty patients low back pain and could not maintain a core contraction. Because the patients presented in a random manner, the patients were matched as close as possible according to age, so as to have better comparative value between the groups (the maximum age difference of a year was instituted). This allowed for comparisons among similar ages, with the difference being their low back pain and core contraction status. Outcome Measure: Each golfer was required to hit 5 balls using a standard club (in this study, a standard driver was used), after which an average value v was calculated for CHV and ball carry. All measurements were carried out using the Flightscope Pro machine at the Durban Pro Shop. Results: Core stability and low back pain did not influence CHV. However there was a non significant trend which indicated higher ball carry in the group with better core stability and no low back pain than in the group with low back pain and poor core stability. Increasing age and handicap reduced the CHV and ball carry values significantly. Ball carry and CHV were positively correlated together in both groups.

It was hypothesized that the number of familiarization sessions may have an effect on the pre-testing measures recorded before a training study. This study considered a group of children (8-12 years old) placed into familiarization (FM, 4 sessions) and non-familiarization (NFM, 2 sessions) groups. Strength values in a vertical chest press and horizontal leg press were recorded for both groups. The FM group displayed strength increases in the chest press, while both groups increased leg press strength (a 0.05). The FM group also displayed significant increases over the NFM group in both exercises. The results demonstrated that, in the FM group, significant changes in chest press strength were made in the last two sessions while significant leg press changes were noted in the first two sessions. It can be concluded that the amount of familiarization sessions performed prior to testing can have an impact on pre-testing strength measures. / School of Physical Education

The purpose of this study was to determine the correlation among three hand strength measurement methods: Hand dynamometer, MDD (Middle Digital Extension Isokinetic Dynamometer), and Cybex. Five students (2 males, 3 females) from Ball State University were asked to participate in this study. Both right and left lower arm data were collected from these subjects. A Cybex 340 (Lumax Cor.) was employed to determine wrist flexion and extension isokinetic peak torque, total work, and power at 30 degrees/second and 60 degrees/second. A MDD was used to determine third digit eccentric torque, work, and power. A hand dynamometer (Lafayette Instrument Co., Model 76618) was used to determine grip force. Pearson product moment correlation coefficients were used to determine correlation among these variables. Significant correlations were noted between isometric grip strength and isokinetic 30 and 60 degrees/second wrist flexion power, as well as between isometric grip strength and isokinetic 30 degrees/second wrist extensor power. The results of this study indicate there is very little relationship between the three clinically used measurement tools. / School of Physical Education

The aim of this study was to establish reference data for the cervical spine’s dynamic force characteristics in a healthy adult urban South African population aged 19 to 69 years. The reference data was classified according to gender discriminate age categories. In total ten gender discriminate age categories, five male and five female, were created; 19 to 29, 30 to 39, 40 to 49, 50 to 59 and 60 to 69-year-olds. The force characteristics measured, analysed and used to generate reference data in stanine format were: absolute peak torque (P-), relative peak torque (P-/BW), peak power (Pow-), relative peak power (Pow-/BW), peak work (W-), relative peak work (W-/BW), torque acceleration energy (TAE-), maximal voluntary cervical muscle contraction range of motion (MVCR-), controlled full range of joint motion (CFR-), joint angle at peak torque (Jang@P-) and peak torque ratios for cervical flexion (-F), extension (-E), lateral flexion to the dominant (-LD) and non-dominant (-LN) sides. In addition biographic and anthropometric data was also collected. Data, grouped in the ten gender discriminate age categories were compared and statistically and practically significant differences were highlighted between the gender discriminate age categories. Inferential statistics used included ANOVA and Cohen’s d. A significance level of α = .05 was used in all inferential statistical analyses. Correlations between various anthropometric and isokinetic strength variables were also explored.

Thesis (M.Tech.: Chiropractic)- Dept. of Chiropractic, Durban University of Technology, 2008. x, 52 leaves, Appendices A-E, [25] leaves. / To determine whether a relationship exists between core stability and bowling speed in Action Cricket bowlers. Methods: Thirty asymptomatic indoor Action Cricket fast and fast-medium bowlers were divided into two groups of 15 each, with Group A having well-developed core stability and group B having poorly-developed core stability. The concept of matched pairs was used for age and cricket experience in order to maintain homogeneity between the groups. The core stability and bowling speed of each participant was measured using a pressure biofeedback unit (PBU) and speed sports radar respectively. SPSS version 15.0 was used to analyse the data.

Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic at the Durban University of Technology, 2009 / Objectives: When we consider the body position of a field hockey player, the lumbar spine is always in a flexed position, which combined with rotational movements during various hitting and pushing techniques, increases the strain upon the spine and surrounding muscles, thus leading to low back pain. To determine the relationship between core strength and trunk extensor endurance relating to the incidence of acute low back pain in field hockey players. Project Design: The research project was in the form of a quantitative cross-sectional study, using human subjects. Setting: The research project occurred during the field hockey season (2008) with players who had acute low back pain. The players were clinically assessed and subdivided into necessary groups at the Chiropractic Day Clinic at the Durban Institute of Technology. Subjects: Adult, male patients, aged between 18 and 30 years of age, playing premier field hockey. Out of the thirty players, 12 players have played in the National u/21 squad, 7 players have played in a Junior National team and 11 players have played senior provincial field hockey. Outcome measure: This included three tests. Firstly, the absolute difference of pressure from the reference value of 70mmHg (prone) and 40mmHg (supine) was used as the outcome measure on a Pressure Biofeedback Unit and length of time (in seconds), a correct contraction of the core stability muscles was maintained. Secondly, the length of time (in seconds) for Trunk Extensor Endurance. Thirdly, repeated measures for NRS-101 and Quebec Back Pain Disability Scale for the duration of the research period. v Results: It was found that there was no statistical evidence or convincing trend to show that the training programmes (core stability and trunk extensor endurance) increased the subjects’ core strength or trunk extensor endurance in the time allocated, although there seemed to be a placebo effect in the Trunk Extensor Group, which showed improvement in some of the core stability outcomes. There was statistical evidence that the intervention (training programmes) reduced pain, according to the Quebec Back Pain Disability Scale (Quebec) score over time, and a non-significant trend suggested this according to the Numerical Rating Scale-101 (NRS). Since both groups’ NRS and Quebec scores were not significantly different at baseline, the difference can be attributed to the effect of the intervention. Conclusions: The results of this study found that the Trunk Extensor Endurance Group, that performed the trunk extensor endurance training programme, yielded better results in core stability and trunk extensor endurance. However, the Core Stability Group, that performed the core stability training programme, showed a quicker reduction in pain levels during the three week intervention period. Therefore, by combining both training programmes, future rehabilitation of athletes suffering from acute low back pain will be more successful. Sport performance of the athletes (field hockey players), through the proponents of swiss ball training, will also improve.