Static strength of tubular DT joints using LUSAS finite element software

Structural tubular are widely used in the construction of offshore structures. As these structures are located in hostile environment, these joints represent structural weak spots and so it is desirable to develop reliable methods of determining their static collapse loads. This studies focus on the analysis of static strength of tubular DT joints under brace compression loading by using LUSAS finite element software. The numerical static strength result is compared with an experimental test result obtained from the literature. The value of the static strength obtained in this work is 56% lower than that of the experimental test. A parameter study was performed to study the effect of the geometric parameters a, ß, y and t as well as the effect of the yield strength sy on the static strength of DT joint model. Finally, a simple equation relating the static strength to the above parameters is proposed

Study on photocatalytic performance of rutile phased TiO2 micro size rods/flowers film towards methyl orange degradation

Pure rutile titanium dioxide (TiO2) film was fabricated at low temperature of l 50°C by hydrothe1mal method. TiO2 film was developed on Fluorine doped tin oxide (FTO) by using titanium butoxide (TBOT) as a precursor, hydrochloric acid (HCI) and deionized (DI) water. The surface morphology of rutile phased TiO2 films were studied by Field Emission Scanning Electron Microscopy (FESEM). X-ray Diffraction (XRD) was used to analyze the structural prope1ty of the films. Energy­dispersive spectroscopy (EDX) was used to verify the elemental property of the films. The photocatalytic degradation of methyl orange (MO) was observed by using UV-vis spectroscopy. The photocatalytic analysis was conducted to compare the ability of rutile phased TiO2 film and P25 film (commercial TiO2). The pH solution was varied from pH 3 to IO to study the favorable pH of TiO2 film. The MO concentration was varied from 5 to 15 ppm to find the limited reaction of TiO2 film. The optimum amount of HCI concentration was 15.88 mol/L while the optimum amount of TiO2 loading was 0.123 mol/L. The optimize reaction time was obtained at 10 hours. No degradation was observed after IO hours. The result shows, 0.123 mol/L TBOT concentration of 1225 nm/ has the highest degradation of MO. The degradation was up to 65.6 % while P25 film was 8.07 % only. MO degradation became insignificant at high concentration. From the experiments, it was found that the rutile phased TiO2 has the higher photocatalytic activity in lower MO concentration and favorable in acidic environment

Fatigue Life of Extended Hollobolt Connection in Concrete Filled Tube

Studies on the performance of blind bolt connections have been carried out by many researchers. A number of recent studies of new blind bolted connection system have been proposed. The system uses the so called Extended Hollobolt fastener to connect the concrete filled tubular columns. The strength performance of this system has been investigated under both monotonic and cyclic loading. However, the performance of such connections under fatigue loading is still unknown.  Therefore, a study to investigate the fatigue performance of Extended Hollobolt was proposed. The main objective of this study is to provide a better understanding of the fatigue life of the proposed blind bolt, consequently provides the design guidance for Extended Hollobolt connection in concrete filled tube. A number of tests were conducted to determine the effect of the frequency and the level of stress range loading on the behaviour of the Extended Hollobolt. The tests were used grade 8.8 bolts subjected to tension. Results show that the frequencies between 0.2 Hz to 5 Hz does affect fatigue life and the stress-range versus fatigue life behaviour of Extended Hollobolt follows the expected pattern of behaviour of standard bolts. The test results of Extended Hollobolt under different stress range then further compared to the normative regulation Eurocode 3. The fatigue life or behaviour of Extended Hollobolt is found to be higher than the theoretical curve of Eurocode 3. Meanwhile, the failure mode of Extended Hollobolt is similar to the standard bolt which is a very positive outcome for blind bolt. However, fatigue life for standard bolt appears to be higher

Fatigue behaviour and reliability of Extended Hollobolt to concrete filled hollow section

The need to provide mechanical connection from one side for the Hollow section connection has arisen in a number of fields and has resulted in the development of several types of so-called blind fasteners. An experimental blind bolt called the Extended Hollobolt is giving a good behaviour performance in terms of stiffness, strength and ductility. The strength performance of this system has been investigated under both monotonic and cyclic loading. However, the performance of such connections under fatigue loading is still unknown. The aim of this study was to investigate the behaviour of blind bolt connection to concrete filled hollow section under repeated load. Further aim was to determine the reliability of the Extended Hollobolt to concrete filled hollow section. The study involved conducting an experimental programme and carrying out fatigue life and reliability analysis. The experiment programme tested 52 specimens of bolts connected to concrete filled hollow sections where 36 tests involved Extended Hollobolt, 10 standard Hollobolt and 6 standard bolts (M16). The test specimens were subjected to tensile fatigue load characteristics with varying stress ranges. Mathematical methods are used to analyse the fatigue test data using the normal, lognormal and Weibull distributions. Normal and lognormal distributions are more suitable. Therefore, statistical analysis procedure proposed by Eurocode for the statistical analysis is valid for fatigue test data. Statistical analysis was conducted to establish S-N curves and to predict the fatigue life of the proposed blind bolt. This was then compared to the normative regulation in Eurocode 3. The failure mode of the Extended Hollobolt under repeated loading was found to be similar with standard bolt, which is a very positive outcome. Statistical analysis of fatigue test data showed that the fatigue life of Extended Hollobolt is higher than the theoretical design S-N curve which is recommended by Eurocode 3 part 1-9 for the standard bolt. However, the actual fatigue life for the standard bolt appears to be higher than the proposed blind bolt. A design model for predicting the fatigue life using S-N curve for the Extended Hollobolt is proposed. A reliability analysis using FORM (First Order Reliability Method) analysis shows that Extended Hollobolt is reliable in connections to concrete filled hollow sections where the safety index is 4.2

Fatigue behaviour and reliability of Extended Hollobolt to concrete filled hollow section

The need to provide mechanical connection from one side for the Hollow section connection has arisen in a number of fields and has resulted in the development of several types of so-called blind fasteners. An experimental blind bolt called the Extended Hollobolt is giving a good behaviour performance in terms of stiffness, strength and ductility. The strength performance of this system has been investigated under both monotonic and cyclic loading. However, the performance of such connections under fatigue loading is still unknown. The aim of this study was to investigate the behaviour of blind bolt connection to concrete filled hollow section under repeated load. Further aim was to determine the reliability of the Extended Hollobolt to concrete filled hollow section. The study involved conducting an experimental programme and carrying out fatigue life and reliability analysis. The experiment programme tested 52 specimens of bolts connected to concrete filled hollow sections where 36 tests involved Extended Hollobolt, 10 standard Hollobolt and 6 standard bolts (M16). The test specimens were subjected to tensile fatigue load characteristics with varying stress ranges. Mathematical methods are used to analyse the fatigue test data using the normal, lognormal and Weibull distributions. Normal and lognormal distributions are more suitable. Therefore, statistical analysis procedure proposed by Eurocode for the statistical analysis is valid for fatigue test data. Statistical analysis was conducted to establish S-N curves and to predict the fatigue life of the proposed blind bolt. This was then compared to the normative regulation in Eurocode 3. The failure mode of the Extended Hollobolt under repeated loading was found to be similar with standard bolt, which is a very positive outcome. Statistical analysis of fatigue test data showed that the fatigue life of Extended Hollobolt is higher than the theoretical design S-N curve which is recommended by Eurocode 3 part 1-9 for the standard bolt. However, the actual fatigue life for the standard bolt appears to be higher than the proposed blind bolt. A design model for predicting the fatigue life using S-N curve for the Extended Hollobolt is proposed. A reliability analysis using FORM (First Order Reliability Method) analysis shows that Extended Hollobolt is reliable in connections to concrete filled hollow sections where the safety index is 4.2

Effect of loading frequency on fatigue life of extended Hollobolt in concrete filled hollow section

A difference in frequency of loading during the test may give a different number of cycles to failure, especially at a higher frequency. The difference becomes more evident when higher frequency was applied at the same stress value. The change of frequency should be analyzed to define its effect on the fatigue life of the Extended Hollobolt to concrete filled hollow section. A number of tests are conducted to determine this effect. Frequencies between 0.25 and 5.0 Hz were applied. Analysis of the result indicates that frequency below 3 Hz does not significantly affect the fatigue life of Extended Hollobolt

Experimental and analytical study of pvc confined concrete cylinders

This study presents results of an experimental research on the concrete filled Poly Vinyl Chloride (PVC) tubes short columns with various typical strengths of the infill concrete; C20, C25, C40. A total of 36 Concrete Filled Tube columns using PVC tubes (CFT PVC) were tested to investigate the column’s behaviour and 18 cylinder concrete column. The columns are 200 mm height, 100 mm external diameter and 3.5 and 4.8 mm tube thickness. The results presented include the maximum axial load, thickness effect, the mode of failure and concrete compressive strength effect. The column resistance shows an increment of between 32.24-83.25% higher compared to the control column specimens. The design equations for the CFT PVC tube columns are proposed

Performance of modified foam concrete-filled column hollow sections

Concrete-filled hollow sections (CFHSs) with foam concrete (FC) are a lightweight material used to reduce structural members' deadweight. Research on applying FC filled into steel hollow sections (SHSs) is still ongoing. The ultimate and compressive strengths of FC-filled SHSs are unsatisfactory, and buckling occurs on the tops or bottoms of their specimens. Therefore, this study aimed to improve the strength and reduce the buckling of CFHSs by using FC added with steel fibre (SF) and rice husk ash (RHA). Rectangular SHS columns with the cross-section dimensions of 100 mm × 100 mm × 2000 mm and 2 and 4 mm thicknesses were tested under static load to determine their strength. The cube test was conducted to determine the compressive strength of the modified FC. Results showed that CFHSs filled with RHA- and SF- modified FC had higher strength than CFHSs filled with RHA-modified FC. Therefore, using modified FC as concrete material in CFHSs is acceptable

The Behavior of Non-Destructive Test for Different Grade of Concrete

Rebound hammer are prefer as non-destructive testing methods; where compression test as destructive test. A general series of tests for rebound hammer and destructive test was carried out at heavy concrete laboratory to obtain the desire result. A set of concrete cubes of sizes 100 x 100 x 100 mm  had been casted and subjected to water curing which was held for 7, 14, 21 and 28 days  to get the exact result of cube strength and rebound number. Rebound hammer testing were initially done before the compression test. The data obtained from each test has been evaluated and tabulated in  this report. From this research, the variation between predicted strength and experimental strength for rebound hammer testing was 1.6%. This indicated rebound hammer testing managed to predict  the strength more accurately. However, non-destructive test shown a margin of less than 10% error compare to destructive test

The face bending behaviour of concrete filled structural hollow sections

This study investigates the face bending of concrete filled SHS when connected to other elements using a type of blind-bolt called the Hollobolt. It looked at analytical bi-Linear model previously proposed to predict the bending behaviour. The model was modified to enhance its accuracy. Testing programme was introduced to investigate modified model, and any further accuracy enhancement. The programme involved applying a tensile force to a row of two bolts attached to concrete filled RHS and recording the face displacement. Two types of bolts were tested; Hollobolts and especially manufactured dummy bolts made to eliminate the Hollobolt slippage. The analysis showed that the accuracy of the proposed computational model was improved. However, it is still conservative, and more work is needed to investigate the correlation between the model and the validation experiments