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Journal Cover Australian Journal of Structural Engineering
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   Full-text available via subscription Subscription journal
   ISSN (Print) 1328-7982
   Published by RMIT Publishing Homepage  [408 journals]
  • Volume 16 Issue 1 - Drift behaviour of lightly reinforced concrete columns
           and structural walls for seismic design applications
    • Abstract: Wilson, JL; Wibowo, A; Lam, NTK; Gad, EF
      This paper presents the findings of a research project investigating the lateral load drift behaviour of lightly reinforced concrete columns and structural walls. Such columns and walls are common in regions of low-moderate seismicity, and although their strength properties are well defined, the drift performance is less understood. A detailed and simplified model for predicting the load-drift behaviour of reinforced concrete columns and structural walls is described in this paper. The results of a case study example are presented and clearly indicate the dramatic impact that the axial load ratio has on the drift performance of lightly reinforced columns, particularly the significantly lower drift capacities that are available in compression dominated columns. The detailed model for both columns and wall specimens provided very good load-drift correlation with an extensive database of experimental tests. In contrast, the simplified model provided a quick, useful, conservative and approximate guide for estimating the drift capacities of reinforced concrete and structural wall specimens for design purposes.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Non-destructive structural integrity assessment of a
           decommissioned rail wagon system
    • Abstract: Bayissa, WL; Dhanasekar, M
      This paper presents a multi-criteria based approach for non-destructive diagnostic structural integrity assessment of a decommissioned flatbed rail wagon (FBRW) used for road bridge superstructure rehabilitation and replacement applications. First, full-scale vibration and static test data sets are employed in a finite element (FE) model of the FBRW to obtain the best "initial" estimate of the model parameters. Second, the "final" model parameters are predicted using sensitivity-based perturbation analysis without significant difficulties encountered. Consequently, the updated FBRW model is validated using the independent sets of full-scale laboratory static test data. Finally, the updated and validated FE model of the FBRW is used for structural integrity assessment of a single lane FBRW bridge subjected to the Australian bridge design traffic load.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - The strength and ductility of lapped splices of
           reinforcing bars in tension
    • Abstract: Gilbert, RI; Kilpatrick, AE
      When designing a reinforced concrete member for strength, ductility and robustness, it is essential that the tensile reinforcement at the critical section can not only develop the yield strength of the steel fsy, but that it can sustain this level of stress as deformation increases. At a lapped splice, each bar must be fully anchored beyond the lap length. The minimum lap lengths of deformed reinforcing bars in tension specified in the Australian Standard for Concrete Structures AS3600- 2009 were recently revised and a procedure similar to, but less conservative than, the provisions in Eurocode 2 was adopted. The new provisions require longer lap lengths for small diameter bars in slabs, but considerably shorter lap lengths for larger diameter bars in beams and columns. This paper reports on several series of tests that examine the efficacy of the AS 3600-2009 provisions from the perspectives of adequate strength and ductility. Over 50 specimens containing both contact and non-contact lapped splices have been tested. The aim was to assess the current Australian provisions and to examine the reliability and consistency of the factors of safety associated with lapped splices. It is concluded that the strength requirements of AS3600-2009 are adequate for small diameter bars in slabs but may not provide an adequate factor of safety for large diameter bars in beams. Also, the AS3600 provisions may not ensure sufficient ductility of a lapped splice in members that use high strength concrete. Further tests are required to investigate these aspects.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Effect of loading pattern and deck confi guration on
           the progressive collapse response of cable-stayed bridges
    • Abstract: Samali, B; Aoki, Y; Saleh, A; Valipour, H
      In the cable stayed-bridges, sudden loss of cables is usually associated with material as well as geometrical non-linearities that may trigger progressive collapse of the entire bridge. Accordingly, in this paper detailed 3D finite element models of a hypothetical cable-stayed bridge is developed and analysed with material and geometrical non-linearities included. A parametric study is undertaken and effect of cable loss scenarios (symmetric and unsymmetric), deck configurations (steel box girder and open orthotropic deck) and number of lost cables on the progressive collapse response of the bridge is investigated. With regard to the results of parametric study, it is concluded that the deck configuration has a minor influence on the progressive collapse response of cablestayed bridges. Also, it is shown that localised yielding of steel may occur following loss of more than one cable, however, such localised plastic strains cannot trigger the progressive collapse of the entire bridge. During cable loss scenarios, the reduction in post-tensioning stress and subsequently stiffness of the remaining cables (reflected in Ernst's modulus) is found to be around 10% that warrants effect of geometrical non-linearities within the cables being considered.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Acceleration-displacement response spectrum vibration
           limits for blast vibrations
    • Abstract: Heath, DJ; Wilson, JL; Gad, EF
      This paper proposes a new method to limit vibrations from blasting to avoid damage to residential structures. The evolution of commonly adopted vibration limits and standards adopted for surface blasting operations in close proximity to residential areas is reviewed. The importance of human sensitivity to vibrations is highlighted and vibration limits preventing damage are demonstrated to be influenced by human annoyance. A robust and rational procedure is presented to replace existing vibration standards limiting vibration using the acceleration displacement response spectrum methodology commonly adopted in earthquake engineering. The proposed approach adopts drift as a measure of damage rather than the current industry accepted measurement of ground velocity.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Preface
    • Abstract: Wilson, John; Gad, Emad
      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Seismic design principles and methodology for the new
           Royal Adelaide Hospital
    • Abstract: McBean, P
      When completed in 2016, the $1.85 billion new Royal Adelaide Hospital will be Australia's newest and most advanced major hospital, and one of the most complex building infrastructure projects delivered in the country. As a critical post disaster facility designed to meet BCA Importance Level 4 criteria, the structure is required to deliver the dual earthquake design performance objectives of collapse prevention for an earthquake with an annual probability of exceedance of 1:1500, together with maintaining full operational capability following a serviceability earthquake with an annual probability of exceedance of 1:500. The earthquake serviceability performance design criterion for Importance Level 4 structures was introduced in the 2007 edition of AS1170.4. The new Royal Adelaide Hospital is one of the first major structures designed to comply with these new provisions. This paper outlines the engineering design processes and strategies adopted for the project to address both the collapse prevention and serviceability earthquake requirements.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 1 - Disaster risk reduction and the earthquake code: A
    • Abstract: Walker, G; Musulin, R
      The application of current earthquake engineering knowledge through structural design codes has greatly reduced the loss of life from earthquakes in countries where the use of such codes has been normal practice for several decades. However it has not had a commensurate effect on disaster risk reduction as was clearly demonstrated in Christchurch by the Canterbury earthquakes. Although the great majority of lives which were lost were the result of the failure of just one modern building - which evidence suggests was from poor design and not a code problem - many modern buildings, while performing well in terms of life safety, were nevertheless damaged beyond repair imposing major economic and social costs on the citizens of Christchurch in particular and, through greatly increased insurance premiums, New Zealand generally. This paper describes the disconnect between the nature of disaster risk reduction and current structural earthquake engineering design philosophy which arises because disasters are a function of community size as well as building vulnerability, whereas current design philosophy is focused entirely on the safety of individual buildings. It draws on ideas jointly developed with the late Paul Grundy and is presented as a tribute to his major contribution to this field.

      PubDate: Mon, 18 May 2015 15:37:22 GMT
  • Volume 16 Issue 2 - Wind loads on the frames of industrial buildings
    • Abstract: Ginger, J; Henderson, D; Humphreys, M; Konthesingha, C; Stewart, MG
      The structural response of typical, gable-end, low roof pitch industrial buildings, in a windstorm is dependent on the wind loads used in the design of cladding and the portal frame structure. Critical, structural wind load effects derived from wind loads measured on a wind tunnel model show that standards such as AS/NZS 1170.2 can produce unconservative design load effects on the heavily loaded first internal frame. This paper forms part of wider study that assesses the vulnerability of hot rolled steel, industrial buildings to wind loads. The knee and ridge bending moments and horizontal and vertical reactions at the base of the frame are the critical load effects that are used in the design of structural members and connections of these types of buildings. This study found that some of these load effects based on external pressures are under-estimated by about 30%, when the building is located in a suburban environment. A dominant windward wall opening can effectively double the design load effects, thus significantly increasing the vulnerability, especially if this scenario has not been considered by the designer.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Finite element modelling of modular precast composites
           for railway track support structure: A battle to save Sydney Harbour
    • Abstract: Griffin, DWP; Mirza, O; Kwok, K; Kaewunruen, S
      Railway networks in Australian alone require replacing a large amount of aging timber components in excess of 280,000 m3/a. The replacement of timber track components is responsible for producing greenhouse gas emissions six times greater than equivalent reinforced concrete counterparts. Sydney Harbour Bridge presently experiences similar problem. A feasibility study to develop an innovative solution for the replacement of aging timber transoms installed on the Sydney Harbour Bridge was conducted to evaluate environmental, safety and financial benefits. The development of alternative composite structure to replace the timber components overcomes some potential compatibility issues with track stiffness as well as structural and geometrical track systems. This study firstly presents a novel and resilient alterative by incorporating steel-concrete composite theory and combining the capabilities of being precast and modular, in order to reduce the depth, weight and required installation time relative to conventional concrete track slab systems. Finite element analysis of the composite structures and its behaviours incorporating the bridge system are highlighted in this paper. A three-dimensional model of steel-concrete composites was developed by using ABAQUS. Non-linear material properties and contact interfaces have been simulated to mimic actual support conditions of existing stringers on the Sydney Harbour Bridge. This investigation demonstrates the safety of the composite panels under train derailment loads.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Simple design formulae for evaluating creep effects in
           prestressed concrete members
    • Abstract: Warner, RF
      Simple design formulae are presented for evaluating the loss of prestress and the flexural deformations (and hence deflection) that occur in a prestressed concrete member as a result of long-term creep. The closed-form equations are approximate, but are accurate enough for use in preliminary design calculations and possibly also in the detailed design of members that are not deflection-sensitive. The equations are not empirical. They are rationally based and transparent, having been derived from a simplified one-step creep analysis.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Effects of creep on the strength of
           eccentricallyloaded slender reinforced concrete columns
    • Abstract: Murray, AL; Gilbert, RI
      Creep and shrinkage effects in concrete structures increase deformations over time but do not normally affect the strength of the structure in any appreciable way. However, for a concrete structure which is subject to second order effects, the loads experienced by the structure are dependent on its deformed shape and therefore the capacity of the structure to withstand the applied loads is dependent on the way it deforms over time. A slender reinforced concrete column is such a structure. This paper presents a first-principles method of analysing the time-dependent behaviour of slender concrete columns subjected to sustained eccentric loads and compares theoretical estimates of critical loads (at which the strength of the critical cross-section is exceeded by creep-induced internal actions) to the allowances made for the design of slender concrete columns by the Australian Standard for Concrete Structures AS3600-2009. In particular, the effects of the concrete compressive strength and the reinforcement ratio are investigated in terms of their influence on the creep-induced reduction of strength of slender columns. The method is based on the principle of superposition and makes use of the age-adjusted effective modulus method to predict the time-dependent behaviour of columns.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Safety factors for the resistance of steel sections
    • Abstract: Kang, W-H; Hicks, S; Uy, B
      The performance of the design equations given in the Australian Bridge and Steel Standards AS 5100.6 and AS 4100 have been evaluated when structural steel is used that conforms with the tolerances within the following overseas manufacturing standards: EN 10034, KS D 3502, JIS F 3192, JIS A 5526, ASTM A6/A6M-07 and AS/NZS 5100.6. From a consideration of the experimental results from full-scale bending tests, reliability analyses according to AS 5104: 2005/ISO 2394:1998 and EN 1990 were conducted. From these analyses, a capacity factor of between 0.93 and 0.95 was determined for beams that have compact, not-compact and non-compact cross-sections when a target reliability index of 3.04 was used, based on the standardised FORM (first order reliability method) sensitivity factor for resistance given in AS 5104: 2005/ISO 2394:1998. This finding demonstrates that the capacity factor of 0.90 given in AS 4100 and AS 5100.6 for beams in bending is on the conservative side for steel sections complying with overseas manufacturing standards, and supports the design practice that has been adopted in NZS 3404.1 for the last 35 years.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Application of quasi-brittle material model for
           analysis of timber members
    • Abstract: Khorsandnia, N; Crews, K
      Over the last two decades many constitutive models with different degrees of accuracy have been developed for analysis of sawn timber and engineered wood products. However, most of the existing models for analysis of timber members are not particularly practical to implement, owing to the large number of material properties (and associated testing) required for calibration of the constitutive law. In order to overcome this limitation, this paper presents details of 1D, 2D and 3D non-linear finite element (FE) models that take advantage of a quasi-brittle material model, requiring a minimum number of material properties to capture the load-deflection response and failure load of timber beams under 4-point bending. In order to validate the model, four tapered timber piles with circular cross-section (two plains and two retrofitted with steel jacket) were tested and analysed with the proposed 3D FE modelling technique; and a good correlation between experimentally observed and numerically captured ultimate load was observed. Consequently, it was concluded that the developed FE models used in conjunction with the quasi-brittle constitutive law were able to adequately capture the failure load and load-deflection response of the flexural timber elements.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Development length in reinforced concrete structures
           exposed to steel corrosion: A correction factor for AS3600 provisions
    • Abstract: Castel, A; Khan, I; Gilbert, RI
      In reinforced concrete structures, reinforcement corrosion induces concrete cracking and leads to a reduction in both the steel cross-section and the steel-concrete bond strength and ultimately affects the development length. In this paper, a new correction factor is proposed to calculate the development length of reinforced concrete structures prone to corrosion. A scalar bond damage parameter is introduced to relate bond strength reduction to corrosion. The new model agrees well with all experimental results found in the literature. The bond damage parameter is further used as a correction factor modifying the AS3600 provisions for the development length of reinforcement in reinforced concrete structures located in a saline environment. The relationship between steel-concrete bond damage and corrosion induced concrete cracking is also discussed.

      PubDate: Mon, 18 May 2015 15:32:00 GMT
  • Volume 16 Issue 2 - Sustainability: A challenge for structural
    • PubDate: Mon, 18 May 2015 15:32:00 GMT
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