Performance of T-stub to CFT joints using blind bolts with headed anchors

This paper assesses the performance of a newly developed blind bolt, intended for use in constructing bolted moment-resisting connections to concrete-filled tubular steel profiles. A total of ten connection tests are reported, with each configuration having been subjected to a predominantly tensile force in a representation of the tension region of a typical moment connection. The test variables included type of fastener, addition of concrete to the tube, strength of the concrete, spacing among bolts, and bolt class. On the basis of reformability response, the benefits of filling the tubular member with concrete are highlighted. The favorable performance that results from using a relatively, high-grade concrete infill is also highlighted. The addition of a concrete infill to the tube stiffens and strengthens the otherwise relatively flexible tube walls, enhancing overall connection behavior in terms of stiffness, strength, and ductility. The performance of connections to concrete-filled tubular steel profiles using blind bolts with headed anchors is shown to be suitable for moment-resisting construction

A component method model for blind-bolts with headed anchors in tension

The successful application of the component-based approach – widely used to model structural joints – requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation, (ii) the connector’s expanding sleeves element, and (iii) the connector’s mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind- bolt’s internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology

Evaluation of current practice and associated challenges towards integrated design

The AEC industry is highly interested in effective ICT adoption and deployment, including its utilization within the design process. However, its capabilities have not yet been fully exploited and it is an obvious area for further research. Architects and engineers tend to have some technological support to monitor and evaluate the possible impacts of decisions made throughout the design process. Many aspects are left out of consideration and the entire project is broken up into independent fragments or domains that are combined together at a later, post hoc stage. Impact of separate decisions on each others have to be interpreted on a person-to-person basis between the involved design stakeholders. This paper attempts to evaluate current design practice and associated challenges towards design integration with advanced technologies, such as BIM, by conducting an online survey targeted at designers and engineers, who are most affected by its emerging issues. The outcomes of this study are presented and analysed, concluding that the current design process fails to meet expectations and needs improvements. It goes further to propose the requirements for an integrated system as a means for an effective solution for the identified problem

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

BIM extension for the sustainability appraisal of conceptual steel design

Contemporary advancements in Information Technology and the efforts from various research initiatives in the AEC industry are showing evidence of progress with the emergence of building information mod- elling (BIM). BIM presents the opportunity of electronically modelling and managing the vast amount of information embedded in a building project, from its conception to end-of-life. Researchers have been looking at extensions to expand its scope. Sustainability is one such modelling extension that is in need of development. This is becoming pertinent for the structural engineer as recent design criteria have put great emphasis on the sustainability credentials in addition to the traditional criteria of structural integrity, constructability and cost. With the complexity of designs, there are now needs to provide deci- sion support tools to aid in the assessment of the sustainability credentials of design solutions. Such tools would be most beneficial at the conceptual design stage so that sustainability is built into the design solu- tion starting from its inception. The sustainability of buildings is related to life cycle and is measured using indicator-terms such as life cycle costing, ecological footprint and carbon footprint. This paper proposes a modelling framework combining these three indicators in providing sustainability assessments of alterna- tive design solutions based on the economic and environmental sustainability pillars. It employs the prin- ciples of feature-based modelling to extract construction-specific information from product models for the purposes of sustainability analysis. A prototype system is implemented using .NET and linked to the BIM enabled software, Revit StructuresTM. The system appraises alternative design solutions using multi-crite- ria performance analysis. This work demonstrates that current process and data modelling techniques can be employed to model sustainability related information to inform decisions right from the early stages of structural design. It concludes that the utilized information modelling representations – in the form of a process model, implementation algorithms and object-based instantiations – can capture sustainability related information to inform decisions at the early stages of the structural design process

Bolts gauge effect on the face bending behaviour of concrete-filled hollow section for hollo-bolted connections

This paper investigates the effect of bolt gauge on the face bending behaviour of concrete-filled Square Hollow Sections (SHS) in Hollo-Bolted connections. A set of full-scale experiments were undertaken to examine the effects of varying the bolt gauge on the SHS face bending behaviour while controlling all other parameters. Typical experiment involved one row of two bolts pulled out of concrete-filled SHS. A special dummy bolts were manufactured to the exact size and geometry of open Hollo-Bolts, and were used in the experiments to remove the influence of any deformation associated with the real Hollo-Bolts, and isolate the face bending behaviour. Non-contact video-based equipment was used to record the SHS face deformation. This deformation is recorded as force-displacement relationship which is commonly used to represent the structural behaviour of similar components, and typically defined by initial stiffness, yield force and post yield stiffness. Across the range considered in this investigation, it was found that varying the bolt gauge to SHS width ratio have a significant effect on the concrete-filled SHS face in bending component. Both the initial stiffness and the yield force of the component were found to increase with the increase of the bolt gauge. The Post-Yield stiffness was not affected by the change in bolt gauge

Pull-out Behaviour of Extended Hollobolts for Hollow Beam-Column Connections

[EN] The use of structural hollow sections (SHS) as columns in single-storey and multi-storey results in better compression strength, low surface area, architectural attractiveness and high strength to weight ratio. One major constraint when connecting to hollow sections is in accessing and tightening the bolt from the inside of the hollow section. To resolve this issue, full welding is usually applied. But this may suffer from high labour cost, and the potential of low quality welding due to workmanship and varied environmental conditions. Connecting using additional components, such as gusset plates and brackets, helps to ease this problem but lowers aesthetic appeal. To avoid the need to access to the inner face of the column section, new type of fasteners known as blind bolts were introduced. In this paper, experimental and numerical studies were conducted using a new anchored blind bolt known as the Extended HolloBolt (EHB), with the objective of using the component method for predicting joint behaviour within the tensile region. The behaviour of EHB in a group with different connection topologies and configurations was investigated using a total of 36 tests with one row of M16 Grade 8.8 and 10.9 bolts subjected to pull-out loading in tension. The experimental work covers a range of parameters such as bolt gauge, concrete strength, concrete type, bolt embedment depth and bolt class. A finite element model was implemented with good agreement between experimental and simulated load-deflection results, which have a maximum difference of 2.5%, shows that the model is suitable to be used for parametric studies or analytical work in further research on the EHB.Bin Shamsudin, MF.; Tizani, W. (2018). Pull-out Behaviour of Extended Hollobolts for Hollow Beam-Column Connections. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 441-448. https://doi.org/10.4995/ASCCS2018.2018.6986OCS44144

A component model for column face in bending of extended HolloBolt connections

Extended HolloBolt (EHB) is a practical anchored blind bolting system for concrete-filled steel sections. One of the failure modes of EHB connections is the bending of the column face component. Up to date, no analytical model to estimate the strength and stiffness of this component have been proposed. This paper aims to develop such model to capture the principal aspects of the overall behaviour of the component, such as its strength and stiffness at different key stages, to represent the component behaviour. The component strength is assumed to be provided by the steel hollow section plate bending and the anchored action. The steel hollow section plate strength models were developed based on the yield line theory. The anchored strength was considered equivalent to the load required to initiate a concrete cone failure. The component stiffness models were formulated using elastic springs, one at each bolt location. The component stiffness was taken equal to the summation of springs stiffness as they act in parallel. The overall bending behaviour of the component was represented by a quad-linear model. The stiffness of the post yield parts of the model was considered as a percentage of the initial stiffness of the component. The model was validated with the available data in the literature and they provided reliable results, which can be considered as a benchmark for the design of EHB connections. This model can be later extended and generalized for other similar blind bolts connections

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