Pub Date : 2016-01-01DOI: 10.18057/IJASC.2016.12.1.4
P. Stephan, C. Love, F. Albermani, H. Karampour
Results from hyperbaric chamber tests of confined buckle propagation using 3m long aluminium pipes with three different D/t ratios are presented and discussed. A new testing method, confined ring squash test, is proposed to estimate the confined buckle propagation pressure. The proposed confined ring squash test gives a reasonable estimate of the confined buckle propagation pressure and is a much expedient test to implement in comparison to hyperbaric chamber test.
{"title":"Experimental study on confined buckle propagation","authors":"P. Stephan, C. Love, F. Albermani, H. Karampour","doi":"10.18057/IJASC.2016.12.1.4","DOIUrl":"https://doi.org/10.18057/IJASC.2016.12.1.4","url":null,"abstract":"Results from hyperbaric chamber tests of confined buckle propagation using 3m long aluminium pipes with three different D/t ratios are presented and discussed. A new testing method, confined ring squash test, is proposed to estimate the confined buckle propagation pressure. The proposed confined ring squash test gives a reasonable estimate of the confined buckle propagation pressure and is a much expedient test to implement in comparison to hyperbaric chamber test.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"12 1","pages":"44-54"},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-06-01DOI: 10.18057/ijasc.2015.11.2.6
C. Iu, M. Bradford
In the finite element modelling of structural frames, external loads such as wind loads, dead loads and imposed loads usually act along the elements rather than at the nodes only. Conventionally, when an element is subjected to these general transverse element loads, they are usually converted to nodal forces acting at the ends of the elements by either lumping or consistent load approaches. In addition, it is especially important for an element subjected to the first- and second-order elastic behaviour, to which the steel structure is critically prone to; in particular the thin-walled steel structures, when the stocky element section may be generally critical to the inelastic behaviour. In this sense, the accurate first- and second-order elastic displacement solutions of element load effect along an element is vitally crucial, but cannot be simulated using neither numerical nodal nor consistent load methods alone, as long as no equilibrium condition is enforced in the finite element formulation, which can inevitably impair the structural safety of the steel structure particularly. It can be therefore regarded as a unique element load method to account for the element load nonlinearly. If accurate displacement solution is targeted for simulating the first- and second-order elastic behaviour on an element on the basis of sophisticated non-linear element stiffness formulation, the numerous prescribed stiffness matrices must indispensably be used for the plethora of specific transverse element loading patterns encountered. In order to circumvent this shortcoming, the present paper proposes a numerical technique to include the transverse element loading in the non-linear stiffness formulation without numerous prescribed stiffness matrices, and which is able to predict structural responses involving the effect of first-order element loads as well as the second-order coupling effect between the transverse load and axial force in the element. This paper shows that the principle of superposition can be applied to derive the generalized stiffness formulation for element load effect, so that the form of the stiffness matrix remains unchanged with respect to the specific loading patterns, but with only the magnitude of the loading (element load coefficients) being needed to be adjusted in the stiffness formulation, and subsequently the non-linear effect on element loadings can be commensurate by updating the magnitude of element load coefficients through the non-linear solution procedures. In principle, the element loading distribution is converted into a single loading magnitude at mid-span in order to provide the initial perturbation for triggering the member bowing effect due to its transverse element loads. This approach in turn sacrifices the effect of element loading distribution except at mid-span. Therefore, it can be foreseen that the load-deflection behaviour may not be as accurate as those at mid-span, but its discrepancy is still trivial as prov
{"title":"NOVEL NON-LINEAR ELASTIC STRUCTURAL ANALYSIS WITH GENERALISED TRANSVERSE ELEMENT LOADS USING A REFINED FINITE ELEMENT","authors":"C. Iu, M. Bradford","doi":"10.18057/ijasc.2015.11.2.6","DOIUrl":"https://doi.org/10.18057/ijasc.2015.11.2.6","url":null,"abstract":"In the finite element modelling of structural frames, external loads such as wind loads, dead loads and imposed loads usually act along the elements rather than at the nodes only. Conventionally, when an element is subjected to these general transverse element loads, they are usually converted to nodal forces acting at the ends of the elements by either lumping or consistent load approaches. In addition, it is especially important for an element subjected to the first- and second-order elastic behaviour, to which the steel structure is critically prone to; in particular the thin-walled steel structures, when the stocky element section may be generally critical to the inelastic behaviour. In this sense, the accurate first- and second-order elastic displacement solutions of element load effect along an element is vitally crucial, but cannot be simulated using neither numerical nodal nor consistent load methods alone, as long as no equilibrium condition is enforced in the finite element formulation, which can inevitably impair the structural safety of the steel structure particularly. It can be therefore regarded as a unique element load method to account for the element load nonlinearly. If accurate displacement solution is targeted for simulating the first- and second-order elastic behaviour on an element on the basis of sophisticated non-linear element stiffness formulation, the numerous prescribed stiffness matrices must indispensably be used for the plethora of specific transverse element loading patterns encountered. In order to circumvent this shortcoming, the present paper proposes a numerical technique to include the transverse element loading in the non-linear stiffness formulation without numerous prescribed stiffness matrices, and which is able to predict structural responses involving the effect of first-order element loads as well as the second-order coupling effect between the transverse load and axial force in the element. This paper shows that the principle of superposition can be applied to derive the generalized stiffness formulation for element load effect, so that the form of the stiffness matrix remains unchanged with respect to the specific loading patterns, but with only the magnitude of the loading (element load coefficients) being needed to be adjusted in the stiffness formulation, and subsequently the non-linear effect on element loadings can be commensurate by updating the magnitude of element load coefficients through the non-linear solution procedures. In principle, the element loading distribution is converted into a single loading magnitude at mid-span in order to provide the initial perturbation for triggering the member bowing effect due to its transverse element loads. This approach in turn sacrifices the effect of element loading distribution except at mid-span. Therefore, it can be foreseen that the load-deflection behaviour may not be as accurate as those at mid-span, but its discrepancy is still trivial as prov","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2015-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-01-01DOI: 10.18057/ijasc.2015.11.1.7
Fernanda Lopes, A. Santiago, L. Silva, N. Iqbal, M. Veljković, José Guilherme Santos da Silva
This paper presents the experimental results of the investigation on the coupled joint-structure behaviour of the composite sub-frame, using the reverse channel connections between an I-beam and th ...
本文介绍了采用工字钢与梁之间的反向通道连接对复合材料副框架的耦合-结构性能进行研究的实验结果。
{"title":"Sub-frames with reverse channel connectiolns to CFT composite columns : experimental evaluation","authors":"Fernanda Lopes, A. Santiago, L. Silva, N. Iqbal, M. Veljković, José Guilherme Santos da Silva","doi":"10.18057/ijasc.2015.11.1.7","DOIUrl":"https://doi.org/10.18057/ijasc.2015.11.1.7","url":null,"abstract":"This paper presents the experimental results of the investigation on the coupled joint-structure behaviour of the composite sub-frame, using the reverse channel connections between an I-beam and th ...","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"54 1","pages":"111-126"},"PeriodicalIF":1.7,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-01-01DOI: 10.18057/IJASC.2015.11.3.3
E. Bruehwiler
A methodology inherent to existing structures is presented for the fatigue safety verification of riveted bridges. The suggested approach allows for the determination of updated action effects explicitly considering data from long term monitoring. Data from monitoring allow for accurate determination of fatigue relevant stresses in fatigue prone bridge elements, and uncertainties in the determination of updated action effects are reduced. By means of the presented approach, the fatigue safety of a riveted railway bridge of high cultural heritage value was verified after 115 years of service duration. Data from monitoring were exploited by Rainflow analysis and served as the basis for the fatigue safety verification. As the locations of measurements are generally not identical with the cross sections of verification, measured strains were translated to the relevant verification cross section by means of factors that were determined by structural analysis. Sufficient fatigue safety was finally verified for the entire riveted structure and additional service duration of at least 50 years was validated.
{"title":"Extending The Fatigue Life Of Riveted Bridges Using Data From Long Term Monitoring","authors":"E. Bruehwiler","doi":"10.18057/IJASC.2015.11.3.3","DOIUrl":"https://doi.org/10.18057/IJASC.2015.11.3.3","url":null,"abstract":"A methodology inherent to existing structures is presented for the fatigue safety verification of riveted bridges. The suggested approach allows for the determination of updated action effects explicitly considering data from long term monitoring. Data from monitoring allow for accurate determination of fatigue relevant stresses in fatigue prone bridge elements, and uncertainties in the determination of updated action effects are reduced. By means of the presented approach, the fatigue safety of a riveted railway bridge of high cultural heritage value was verified after 115 years of service duration. Data from monitoring were exploited by Rainflow analysis and served as the basis for the fatigue safety verification. As the locations of measurements are generally not identical with the cross sections of verification, measured strains were translated to the relevant verification cross section by means of factors that were determined by structural analysis. Sufficient fatigue safety was finally verified for the entire riveted structure and additional service duration of at least 50 years was validated.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"11 1","pages":"283-293"},"PeriodicalIF":1.7,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.18057/ijasc.2014.10.2.4
J. Ho, C. Dong
One of the significant contributions of using double-skinned concrete-filled-steel-tubular (CFST) columns is that it can extend the maximum limit of concrete strength that can be practically used in the construction industry, by improving the ductility of columns through providing more uniform and continuous confining pressure to the in-filled concrete. However, because of the imperfect interface bonding occurs at early stage, the elastic strength and stiffness will decrease so that the confinement effect provided by the steel tube is not fully utilized. To improve the situation, the authors have proposed to use external confinement in the form of steel rings on the outer steel tube to restrict the dilation of CFST columns and thus restore an intact interface bonding condition. It has been verified by uni-axial compression test that the elastic strength, stiffness and interface bonding were improved. Based on the test results, the authors have developed a theoretical model for predicting the uni-axial load-carrying capacity of doubled-skinned CFST columns. As a continued study, the authors will investigate the most critical parameters affecting the uni-axial strength, and to develop a simplified formula for practical design of doubled-skinned CFST columns through an extensive parametric study.
{"title":"Simplified Design Model for Uni-Axially Loaded Double-Skinned Concrete-Filled-Steel-Tubular Columns with External Confinement","authors":"J. Ho, C. Dong","doi":"10.18057/ijasc.2014.10.2.4","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.2.4","url":null,"abstract":"One of the significant contributions of using double-skinned concrete-filled-steel-tubular (CFST) columns is that it can extend the maximum limit of concrete strength that can be practically used in the construction industry, by improving the ductility of columns through providing more uniform and continuous confining pressure to the in-filled concrete. However, because of the imperfect interface bonding occurs at early stage, the elastic strength and stiffness will decrease so that the confinement effect provided by the steel tube is not fully utilized. To improve the situation, the authors have proposed to use external confinement in the form of steel rings on the outer steel tube to restrict the dilation of CFST columns and thus restore an intact interface bonding condition. It has been verified by uni-axial compression test that the elastic strength, stiffness and interface bonding were improved. Based on the test results, the authors have developed a theoretical model for predicting the uni-axial load-carrying capacity of doubled-skinned CFST columns. As a continued study, the authors will investigate the most critical parameters affecting the uni-axial strength, and to develop a simplified formula for practical design of doubled-skinned CFST columns through an extensive parametric study.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"62 1","pages":"179-199"},"PeriodicalIF":1.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.18057/ijasc.2014.10.2.1
R. Singh, E. Lui
Partially restrained (PR) connections are connections that possess stiffness and moment characteristics that fall between the extreme cases of pinned and rigid. This paper proposes a design methodology for PR frames that takes into consideration the semi-rigid nature of the connections, including their loading/unloading behavior under combined gravity and wind loads. Top and seat angle connections, modeled using the three-parameter power model, are used to demonstrate the proposed design procedure. To simply the design, two linearized connection stiffness values calculated on the basis of expected connection loads are used. The analysis is carried out using the American Institute of Steel Construction (AISC) direct analysis method in which notional horizontal loads, expressed as a fraction of the gravity load, are applied to the PR frames in conjunction with the use of reduced member axial and bending stiffness. Examples are given to demonstrate the validity of the proposed method of PR frame design.
{"title":"Design of pr frames with top and seat angle connections using the direct analysis method","authors":"R. Singh, E. Lui","doi":"10.18057/ijasc.2014.10.2.1","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.2.1","url":null,"abstract":"Partially restrained (PR) connections are connections that possess stiffness and moment characteristics that fall between the extreme cases of pinned and rigid. This paper proposes a design methodology for PR frames that takes into consideration the semi-rigid nature of the connections, including their loading/unloading behavior under combined gravity and wind loads. Top and seat angle connections, modeled using the three-parameter power model, are used to demonstrate the proposed design procedure. To simply the design, two linearized connection stiffness values calculated on the basis of expected connection loads are used. The analysis is carried out using the American Institute of Steel Construction (AISC) direct analysis method in which notional horizontal loads, expressed as a fraction of the gravity load, are applied to the PR frames in conjunction with the use of reduced member axial and bending stiffness. Examples are given to demonstrate the validity of the proposed method of PR frame design.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"54 3 1","pages":"116-138"},"PeriodicalIF":1.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-03-01DOI: 10.18057/ijasc.2014.10.1.4
S. Hatami, A. Rahmani, Ali Parvaneh, H. Ronagh
Shear wall panels, including cold-formed steel frames and its attached sheathing, are common lateral load resisting systems of cold-founed steel structures. In this paper, the finite element method is used to study the lateral performance of shear wall panels. The finite element model is validated against experimental results of other researchers. Using the validated model, a parametric study is described to determine strength, drift and seismic behavior of the shear wall panels. Based on the results, it is concluded that the initial stiffness and ultimate lateral strength are dramatically affected by the thickness of the frame members, type of sheathing material, edge screw spacing, height of the frame, while some parameters such as field screw spacing have a minor effect on the initial stiffness and the ultimate lateral strength. In addition, this study looks into the earthquake performance of the shear wall panels and presents the corresponding ductility factor and force reduction factor (R-factor) of shear wall panels.
{"title":"A PARAMETRIC STUDY ON SEISMIC CHARACTERISTICS OF COLD-FORMED STEEL SHEAR WALLS BY FINITE ELEMENT MODELING","authors":"S. Hatami, A. Rahmani, Ali Parvaneh, H. Ronagh","doi":"10.18057/ijasc.2014.10.1.4","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.1.4","url":null,"abstract":"Shear wall panels, including cold-formed steel frames and its attached sheathing, are common lateral load resisting systems of cold-founed steel structures. In this paper, the finite element method is used to study the lateral performance of shear wall panels. The finite element model is validated against experimental results of other researchers. Using the validated model, a parametric study is described to determine strength, drift and seismic behavior of the shear wall panels. Based on the results, it is concluded that the initial stiffness and ultimate lateral strength are dramatically affected by the thickness of the frame members, type of sheathing material, edge screw spacing, height of the frame, while some parameters such as field screw spacing have a minor effect on the initial stiffness and the ultimate lateral strength. In addition, this study looks into the earthquake performance of the shear wall panels and presents the corresponding ductility factor and force reduction factor (R-factor) of shear wall panels.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"10 1","pages":"53-71"},"PeriodicalIF":1.7,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-01DOI: 10.18057/ijasc.2014.10.4.7
M. Gu, L. Tong, X. Zhao, Yunfeng Zhang
Fatigue life assessment of welded joints made of circular hollow sections (CHS) with concrete filled (CF) chord member subject to vehicle load is vital in designing of CFCHS arch truss bridge. A key issue in fatigue life assessment of such joints is how to accurately estimate the stress intensity factor. This paper describes a methodology for calculating the stress intensity factor of the hot spot region in the welded CFCHS T-joints based on a finite element analysis which considers weld modeling, crack modeling and nonlinear interface element between steel and concrete. A procedure for fatigue life estimation of welded CFCHS T-joints is also established. Discussions are made on the effect of the initial crack size and concrete strength on fatigue life and hot spot stresses. The majority of crack propagation life is found to be associated with the shallow crack stage. The proposed method gives reasonable estimation of fatigue life of welded CFCHS T-joints.
{"title":"Numerical analysis of fatigue behavior of welded cfchs T-joints","authors":"M. Gu, L. Tong, X. Zhao, Yunfeng Zhang","doi":"10.18057/ijasc.2014.10.4.7","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.4.7","url":null,"abstract":"Fatigue life assessment of welded joints made of circular hollow sections (CHS) with concrete filled (CF) chord member subject to vehicle load is vital in designing of CFCHS arch truss bridge. A key issue in fatigue life assessment of such joints is how to accurately estimate the stress intensity factor. This paper describes a methodology for calculating the stress intensity factor of the hot spot region in the welded CFCHS T-joints based on a finite element analysis which considers weld modeling, crack modeling and nonlinear interface element between steel and concrete. A procedure for fatigue life estimation of welded CFCHS T-joints is also established. Discussions are made on the effect of the initial crack size and concrete strength on fatigue life and hot spot stresses. The majority of crack propagation life is found to be associated with the shallow crack stage. The proposed method gives reasonable estimation of fatigue life of welded CFCHS T-joints.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"10 1","pages":"476-497"},"PeriodicalIF":1.7,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-01DOI: 10.18057/ijasc.2014.10.3.1
Jui-Lin Peng, C. Ho, Chen-yu Chen, Yeong-Bin Yang
The isolated heavy-duty scaffolds, which have higher load capacity, are often considered to serve as the falsework during the construction stage of a building with high clearance, large spans and thick slabs in order to meet the load demand of the building. Because isolated heavy-duty scaffolds serve as temporary structures and are promptly dismantled after the construction is complete, their importance is often neglected. Until now, data regarding the structural design of isolated heavy-duty scaffolds has been rather scarce, and the assembly of isolated heavy-duty scaffolds on construction sites still relies mainly on the experience of construction workers. This phenomenon results in a high risk of collapse of isolated heavy-duty scaffolds actually applied on construction sites. This study explores the critical loads and the failure modes of isolated heavy-duty scaffolds in various setups by testing actual setups of isolated heavy-duty scaffolds on construction sites. The results show that, since the bending moment stiffness provided by the base screw jacks of isolated heavy-duty scaffolds is negligible, the base screw jack has a limited effect on the overall load capacity of isolated heavy-duty scaffolds. When isolated heavy-duty scaffolds are set up on ground with varying elevation or on ground under an inclined top slab with varying elevation, their load capacity is not substantially affected as long as the difference in elevation is less than 56 cm. When assembled in multiple layers on construction sites, isolated heavy-duty scaffolds are often erected with steel tube shores on the top layer. However, this combined scaffolding structure reduces the load capacity of isolated heavy-duty scaffolds by as much as 70%. In this case, directly extending the top screw jacks of the isolated heavy-duty scaffolds is better than using a combined scaffolding structure. As for the isolated heavy-duty scaffolds after being repeatedly used, this study uses a repeated loading test to simulate the lower bound strength of isolated heavy-duty scaffolds on construction sites. Contractors can choose an appropriate reduction factor based on cost and construction safety considerations when engineers design the strengths of reusable isolated heavy-duty scaffolds.
{"title":"EXPERIMENTAL STUDY ON LOAD CAPACITIES OF ISOLATED HEAVY-DUTY SCAFFOLDS USED IN CONSTRUCTION","authors":"Jui-Lin Peng, C. Ho, Chen-yu Chen, Yeong-Bin Yang","doi":"10.18057/ijasc.2014.10.3.1","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.3.1","url":null,"abstract":"The isolated heavy-duty scaffolds, which have higher load capacity, are often considered to serve as the falsework during the construction stage of a building with high clearance, large spans and thick slabs in order to meet the load demand of the building. Because isolated heavy-duty scaffolds serve as temporary structures and are promptly dismantled after the construction is complete, their importance is often neglected. Until now, data regarding the structural design of isolated heavy-duty scaffolds has been rather scarce, and the assembly of isolated heavy-duty scaffolds on construction sites still relies mainly on the experience of construction workers. This phenomenon results in a high risk of collapse of isolated heavy-duty scaffolds actually applied on construction sites. This study explores the critical loads and the failure modes of isolated heavy-duty scaffolds in various setups by testing actual setups of isolated heavy-duty scaffolds on construction sites. The results show that, since the bending moment stiffness provided by the base screw jacks of isolated heavy-duty scaffolds is negligible, the base screw jack has a limited effect on the overall load capacity of isolated heavy-duty scaffolds. When isolated heavy-duty scaffolds are set up on ground with varying elevation or on ground under an inclined top slab with varying elevation, their load capacity is not substantially affected as long as the difference in elevation is less than 56 cm. When assembled in multiple layers on construction sites, isolated heavy-duty scaffolds are often erected with steel tube shores on the top layer. However, this combined scaffolding structure reduces the load capacity of isolated heavy-duty scaffolds by as much as 70%. In this case, directly extending the top screw jacks of the isolated heavy-duty scaffolds is better than using a combined scaffolding structure. As for the isolated heavy-duty scaffolds after being repeatedly used, this study uses a repeated loading test to simulate the lower bound strength of isolated heavy-duty scaffolds on construction sites. Contractors can choose an appropriate reduction factor based on cost and construction safety considerations when engineers design the strengths of reusable isolated heavy-duty scaffolds.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"57 1","pages":"248-273"},"PeriodicalIF":1.7,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-01DOI: 10.18057/ijasc.2014.10.4.6
S. Fawzia, Kaniz Shahanara
This paper presents a nonlinear finite element (FE) model for the analysis of very high strength (VHS) steel hollow sections wrapped by high modulus carbon fibre rein forced polymer (CFRP) sheets. The bond strength of CFRP wrapped VHS circular steel hollow section under tension is investigated using the FE model. The three dimensional FE model by Nonlinear static analysis has been carried out by Strand 7 finite element software. The model is validated by the experimental data obtained from Fawzia et al [1]. A detail parametric study has been performed to examine the effect of number of CFRP layers, different diameters of VHS steel tube and different bond lengths of CFRP sheet. The analytical model developed by Fawzia et al. [1] has been used to determine the load carrying capacity of different diameters of CFRP strengthened VHS steel tube by using the capacity from each layer of CFRP sheet. The results from FE model have found in reasonable agreement with the analytical model developed by Fawzia et al [1]. This validation was necessary because the analytical model by Fawzia et al [1] was developed by using only one diameter of VHS steel tube and fixed (five) number of CFRP layers. It can be concluded that the developed analytical model is valid for CFRP strengthened VHS steel tubes with diameter range of 38mm to 100mm and CFRP layer range of 3 to 5 layers. Based on the results it can also be concluded that the effective bond length is consistent for different diameters of steel tubes and different layers of CFRP. Three layers of CFRP is considered most effective wrapping scheme due to the cost effectiveness. Finally the distribution of longitudinal and hoop stress has been determined by the finite element model for different diameters of CFRP strengthened VHS steel tube.
{"title":"Finite element analysis of CFRP strengthened steel hollow sections under tension","authors":"S. Fawzia, Kaniz Shahanara","doi":"10.18057/ijasc.2014.10.4.6","DOIUrl":"https://doi.org/10.18057/ijasc.2014.10.4.6","url":null,"abstract":"This paper presents a nonlinear finite element (FE) model for the analysis of very high strength (VHS) steel hollow sections wrapped by high modulus carbon fibre rein forced polymer (CFRP) sheets. The bond strength of CFRP wrapped VHS circular steel hollow section under tension is investigated using the FE model. The three dimensional FE model by Nonlinear static analysis has been carried out by Strand 7 finite element software. The model is validated by the experimental data obtained from Fawzia et al [1]. A detail parametric study has been performed to examine the effect of number of CFRP layers, different diameters of VHS steel tube and different bond lengths of CFRP sheet. The analytical model developed by Fawzia et al. [1] has been used to determine the load carrying capacity of different diameters of CFRP strengthened VHS steel tube by using the capacity from each layer of CFRP sheet. The results from FE model have found in reasonable agreement with the analytical model developed by Fawzia et al [1]. This validation was necessary because the analytical model by Fawzia et al [1] was developed by using only one diameter of VHS steel tube and fixed (five) number of CFRP layers. It can be concluded that the developed analytical model is valid for CFRP strengthened VHS steel tubes with diameter range of 38mm to 100mm and CFRP layer range of 3 to 5 layers. Based on the results it can also be concluded that the effective bond length is consistent for different diameters of steel tubes and different layers of CFRP. Three layers of CFRP is considered most effective wrapping scheme due to the cost effectiveness. Finally the distribution of longitudinal and hoop stress has been determined by the finite element model for different diameters of CFRP strengthened VHS steel tube.","PeriodicalId":56332,"journal":{"name":"Advanced Steel Construction","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67606710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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