An investigation into adequacy of separation gap to preclude earthquake-induced pounding

Yazan Jaradat,Pejman Sobhi,Harry Far 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.1

Pounding happens when contiguous structures with differing heights vibrate out of line caused by a seismic activity. The situation is aggravated due to the insufficient separation gap between the structures which can lead to the crashing of the buildings or total collapse of an edifice. Countries around the world have compiled building standards to address the pounding issue. One of the strategies recommended is the introduction of the separation gap between structures. AS1170.4-2007 is an Australian standard that requires 1% of the building height as a minimum separation gap between buildings to preclude pounding. This article presents experimental and numerical tests to determine the adequacy of this specification to prevent the occurrence of seismic pounding between steel frame structures under near-field and far-field earthquakes. The results indicated that the recommended minimum separation gap based on the Australian Standard is inaccurate if low-rise structure in a coupled case is utilised under both near and far field earthquakes. The standard is adequate if a tall building is involved but only when a far-field earthquake happens. The research likewise presents results derived by using the ABS and SRSS methods.

Numerical Investigation on Shear Deflection of Steel Welded I Sections with Varying Span to Depth Ratios

Salman Kamali,Harry Far 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2

Defl ection of the steel I-sections is an important phenomenon that needs to be taken into account to ensure that the serviceability limit state criteria of the Australian Standards are met. The method that is widely used to calculate the defl ection of steel I-sections is by the use of existing formulae that only accommodate the bending stiff ness of the beams. A numerical investigation is performed in this study to fi nd the contribution of shear eff ects in the fi nal defl ection of the Welded-Beams (WB) and Welded-Columns (WC). The numerical analyses were carried out in SAP2000 and numerical model was fi rst validated using the experimental results of welded plate girders. The model was then used to analyse simply supported WB and WC sections under uniformly distributed load (UDL) with varying span lengths. The results of the numerical analyses are reported in this study which compare the mid-span defl ection values from the simply supported defl ection formula with the numerical model defl ection values. The data acquired from the numerical analyses were used to establish a span to depth ratio for WB and WC sections below which the shear defl ection becomes signifi cant. The analysis of the results obtained from the numerical investigation suggests that a predication error begins to emerge in the result that is acquired from fl exure defl ection formulae at a certain span-depth ratio.

Determination of slip modulus of cold-formed steel composite members sheathed with plywood structural panels

Dheeraj Karki,Harry Far,Suleiman Al-hunity 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.4

An experimental investigation to study the behaviour of connections between cold-formed steel (CFS) joist and plywood structural panel is presented in this paper. Material testing on CFS and plywood was carried out to assess their mechanical properties and behaviour. Push-out tests were conducted to determine the slip modulus and failure modes of three different shear connection types. The employed shear connectors in the study were; size 14 (6mm diameter) self-drilling screw, M12 coach screw, and M12 nut and bolt. The effective bending stiffness of composite cold-formed steel and plywood T-beam assembly is calculated based on the slip modulus values computed from push-out tests. The effective bending stiffness was increased by 25.5%, 18% and 30.2% for self-drilling screw, coach screw, nut and bolt, respectively, over the stiffness of coldformed steel joist alone. This finding suggests the potential to enhance the structural performance of composite cold-formed steel and timber flooring system by mobilisation of composite action present between timber sheathing and CFS joist.

Optimum stiffness values for impact element models to determine pounding forces between adjacent buildings

Yazan Jaradat,Harry Far 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.2

Structural failure due to seismic pounding between two adjacent buildings is one of the major concerns in the context of structural damage. Pounding between adjacent structures is a commonly observed phenomenon during major earthquakes. When modelling the structural response, stiffness of impact spring elements is considered to be one of the most important parameters when the impact force during collision of adjacent buildings is calculated. Determining valid and realistic stiffness values is essential in numerical simulations of pounding forces between adjacent buildings in order to achieve reasonable results. Several impact model stiffness values have been presented by various researchers to simulate pounding forces between adjacent structures. These values were mathematically calculated or estimated. In this study, a linear spring impact element model is used to simulate the pounding forces between two adjacent structures. An experimental model reported in literature was adopted to investigate the effect of different impact element stiffness k on the force intensity and number of impacts simulated by Finite Element (FE) analysis. Several numerical analyses have been conducted using SAP2000 and the collected results were used for further mathematical evaluations. The results of this study concluded the major factors that may actualise the stiffness value for impact element models. The number of impacts and the maximum impact force were found to be the core concept for finding the optimal range of stiffness values. For the experimental model investigated, the range of optimal stiffness values has also been presented and discussed.

Structural Behaviour and Mechanical Properties of Welded Steel I-Girders with Corrugated Webs

Xuqun Lin,Harry Far,Ali Saleh 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4

Steel I girders with corrugated webs are appropriate alternatives for normal fl at-web girders in steel structures since they provide lighter and smaller beam features in steel design. Based on the existing literature, the corrugated web beams (CWBs) provide many advantages for structural applications. In this study, a series of numerical analyses have been performed in order to investigate the structural behaviour of steel I girders with corrugated web profi le and to compare their mechanical performance with normal welded beams. Theory of Ultimate Limit State design has been adopted in accordance with AS4100 (Steel structures, Standard Australia, Sydney, 1998 ) along with considering geometric and material non-linearity in the numerical analyses in SAP2000. Comparing the results of the numerical investigation, merits of using corrugated welded beams (CWBs) over normal welded beams (WBs) have become apparent. Moreover, investigations regarding force–displacement relationship and buckling analysis of the webs were carried out and presented to further validate the advantages of using corrugated web beams. CWBs have been used in some parts of Australia without detailed information about their mechanical properties. Thus, based on the outcomes of this study, CWB table for dimensions and cross sectional properties has been developed and proposed for practical applications.

Shear Capacity Analysis of Welded Steel I-Girders with Corrugated Webs based on First Yield

Xuqun Lin,Harry Far,Xutong Zhang 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

Steel I beams or girders with sinusoidal corrugated profi le webs have become popular in the recent development of the steel structural designs, since corrugated-web beams (CWBs) can provide better performance in terms of less deformation and more stability against buckling failure. It is verifi ed in previous research that CWBs can be considered as an alternative to replace normal beams in the structural designs with their numerous favourable features. Since CWBs are being used as the main structural elements, it is apparent that some essential practical properties of this type of beams should be studied, where the prediction of the shear capacity is one of the most signifi cant design aspects that should be accurately investigated. Calculations to the design formulas from other standards and several fi nite element simulations have been carried out to compare the diff erences in obtained results and to fi nd an adequate approach to calculate the shear capacity of CWBs for the Australian civil engineering community. Ultimate Limit State design theory has been utilised in conjunction with AS4100 ( 2017 ) along with linear analysis in SAP2000. By comparing the results of the theoretical calculations and numerical simulations, it has been concluded that the highly formed equations presented by EN 1993-1-5 (Design of Steel Structures Part 1–5: Plated Structural Elements, Eurocode 3, Brussels, 2006), Hancock et al. ( 2012 ) could well estimate the shear capacity constraining requirements and rules in accordance with Australian standards, which can be adequately used in Australian structural design fi elds.

Post-buckling Strength of Welded Steel I-Girders with Corrugated Webs

Xuqun Lin,Harry Far 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

Steel I-section-plate girders with corrugated webs have been used worldwide as they provide more stability and light beam features in practical design. It is known from previous investigations that due to having numerous favourable properties, the corrugated-web beams have been used in diff erent areas of structural engineering. Considering the raising popularity of using CWBs in steel design, some practical aspects of CWBs need to be investigated further, in which post-buckling strength is one of the most critical strengths that should be precisely estimated. To fulfi ll this requirement regarding the post-bucking strength determination for structural designers community, a numerical investigation has been conducted in this study to determine the moment capacity reduction factors for steel I girders with corrugated-web profi le and to compare reduction factor values extracted from EN 1993-1-5 (Design of steel structures part 1–5: Plated structural elements, Eurocode 3, Brussels, 2006), AS4100 (Steel structures, Standard Australia, Sydney, 1998), and fi nite element analysis. Theory of Ultimate Limit State design has been adopted in accordance with AS4100 (1998) along with considering geometric and material non-linearity in the numerical analyses in SAP2000 software. Eventually, the results of the parametric study have been compared and discussed leading to presenting practical recommendations on the design of CWBs for bending strength.

Investigation on structural behaviour of composite cold-formed steel and reinforced concrete flooring systems

Omar A. Shamayleh,Harry Far 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.6

Composite flooring systems consisting of cold-formed steel joists and reinforced concrete slabs offer an efficient, lightweight solution. However, utilisation of composite action to achieve enhanced strength and economical design has been limited. In this study, finite element modelling was utilised to create a three-dimensional model which was then validated against experimental results for a composite flooring system consisting of cold-formed steel joists, reinforced concrete slab and steel bolt shear connectors. This validated numerical model was then utilised to perform parametric studies on the performance of the structural system. The results from the parametric study demonstrate that increased thickness of the concrete slab and increased thickness of the cold formed steel beam resulted in higher moment capacity and stiffness of the composite flooring system. In addition, reducing the spacing of bolts and spacing of the cold formed steel beams both resulted in enhanced load capacity of the composite system. Increasing the concrete grade was also found to increase the moment capacity of the composite flooring system. Overall, the results show that an efficient, lightweight composite flooring system can be achieved and optimised by selecting suitable concrete slab thickness, cold formed beam thickness, bolt spacing, cold formed beam spacing and concrete grade.

Vibration behaviour of cold-formed steel and particleboard composite flooring systems

Suleiman A. AL Hunaity,Harry Far,Ali Saleh 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.3

Recently, there has been an increasing demand for buildings that allow rapid assembly of construction elements, have ample open space areas and are flexible in their final intended use. Accordingly, researchers have developed new competitive structures in terms of cost and efficiency, such as cold-formed steel and timber composite floors, to satisfy these requirements. Cold-formed steel and timber composite floors are light floors with relatively high stiffness, which allow for longer spans. As a result, they inherently have lower fundamental natural frequency and lower damping. Therefore, they are likely to undergo unwanted vibrations under the action of human activities such as walking. It is also quite expensive and complex to implement vibration control measures on problematic floors. In this study, a finite element model of a composite floor reported in the literature was developed and validated against four-point bending test results. The validated FE model was then utilised to examine the vibration behaviour of the investigated composite floor. Predictions obtained from the numerical model were compared against predictions from analytical formulas reported in the literature. Finally, the influence of various parameters on the vibration behaviour of the composite floor was studied and discussed.

Natural time period equations for moment resisting reinforced concrete structures comprising hollow sections

Satya Sundar Prajapati,Harry Far,Mehdi Aghayarzadeh 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.4

A precise estimation of the natural time period of buildings improves design quality, causes a significant reduction of the buildings’ weight, and eventually leads to a cost-effective design. In this study, in order to optimise the reinforced concrete frames design, some symmetrical and unsymmetrical buildings composed of solid and hollow members have been simulated using finite element software SAP 2000. In numerical models, different parameters such as overturning moment, story drift, deflection, base reactions, and stiffness of the buildings were investigated and the results have been compared with strength and serviceability limit criteria proposed by Australian Standard (AS 3600 2018). Comparing the results of the numerical modelling with existing standards and performing a cost analysis proved the merits of hollow box sections compared to solid sections. Finally, based on numerical simulation results, two equations for natural time period of moment resisting reinforced concrete buildings have been presented. Both derived equations reflected higher degree of correlation and reliability with different complexities of building when compared with existing standards and relationships provided by other scholars. Therefore, these equations will assist practicing engineers to predict elastic behaivour of structures more precisely.