A number of journal papers have recently been published that have been co-authored by our General Manager Structural SystemsDr Stephen Hicks.
They’re now available to members from our library. Details for each of these papers are given below.
Safety Factors for the Resistance of Steel Sections
Australian Journal of Structural Engineering, by Kang WH, Hicks S and 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 G 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.
Design strength of concrete-filled steel columns
Advanced Steel Construction Journal, by Kang WH, Uy B, Tao Z and Hicks S – The purpose of this paper is to recalibrate the capacity reduction factors, estimate the reliability of current equations, and investigate the effect of these factors in AS 5100.6, the Australian Bridge Standard for concrete-filled steel tubular columns.
This work has important ramifications for other international codes of practice as the Australian code has the identical or similar underlying design philosophy with Eurocode 4, AISC and the code of practice in Hong Kong.
The method developed by Johnson and Huang is extensively applied to the Australian code format to recalibrate the capacity factors in AS 5100 for a target reliability of = 3.04 based on an extensive database of 1,583 test results covering a wide range of input parameter values. In addition, an inverse analysis procedure based on Johnson and Huang’s method is proposed to estimate the reliability of design equations with known capacity factors.
The analysis results show that the interaction between the concrete and steel needs to be considered for the current capacity factors in AS 5100.
The results also show that the current capacity factors provide greater reliability than the target reliability suggested in AS 5104:2005/ISO 2394:1998, but after considering the additional uncertainties created due to the application of multiple capacity factors, the reliability was almost the same as the recommended value.
In conclusion, the current capacity factor values in AS 5100 are adequate with regards to safety and can be maintained, but better optimised values would be preferable to improve the cost-safety balance.
Design of slim-floor construction for human-induced vibrations
Steel Construction Journal, by Hicks S and Peltonen – This paper presents a simplified design method for evaluating the vibration response of composite floors with slim-floor beams. The methodology is amenable to hand calculations and is appropriate for floors with regularly spaced grids and vibrations that are occasioned by walking activities.
From in-situ tests that have been undertaken on six floors, it is shown that slim-floor construction can easily satisfy the demanding ISO 10137 response limits for operating theatres and laboratories together with limits recommended by industry for car parks and shopping malls.
Comparisons with measurements show that the simplified method presented here provides conservative predictions, and may therefore be used with confidence in design.
Partial factors for the design resistance of composite beams in bending
(Journal of Constructional Steel Research, by Hicks SJ and Pennington A – This paper presents the results from a reliability analysis of the resistance of composite beams in sagging bending designed according to Eurocode 4. Using the EN 1990 methodology, the partial factors yM for the structural steel, concrete and shear connection were evaluated.
The present study extends earlier work by considering geometrical tolerances given within the published European product and execution standards, which were unavailable during the original calibration of Eurocode 4. Furthermore, recently reported European production data on the yield strength of structural steel is also included.
The analyses consider test data from 164 beams with full shear connection, partial shear connection, ductile connectors, non-ductile connectors and beams with high strength steel, which are supplemented with over 3 million simulations.
It was found in the present work that the current recommended values for yM were only justified for beams with full shear connection. For beams with partial shear connection, the calculated values of yM were larger than recommended because the partial factor associated with the uncertainty of the resistance model varied considerably.
To remedy this situation, conversion factors that are a function of the overall composite beam depth are proposed which, when applied to the design models, justifies lower partial factors than that currently recommended by Eurocode 4.