Zealand Code Research Articles

Nonlinear analysis and design of high-strength concrete filled steel tubular columns under nonuniform fires

The main objective of this study is to investigate the behaviour of concrete-filled steel tubular (CFST) columns with ultra-high strength concrete (UHSC) and high strength steel (HSS) under fires through finite element method (FEM). High-strength materials can be used in CFST columns to reduce member dimensions, lowering material consumption and foundation loads. However, their fire behaviour has been insufficiently examined, especially under nonuniform fire exposure. In this study, thermal-structural models of the composite columns are developed using the SAFIR software. The numerical results are compared with published test data on temperature distribution, axial displacement, lateral displacement, failure modes and failure time. Then, parametric analyses are conducted to investigate the influence of various factors such as concrete strength, steel strength, different fire exposures, column length and load ratio on the fire performance of the CFST columns. In addition, the tabular design approach in European code EN1994–1-2 and Australian/New Zealand code AS/NZS 2327:2017 for designing uniformly exposed CFST columns is evaluated. It is observed that the prescribed design values in the table for R30 and R60 fire ratings under load ratio lower than 0.47 appear insufficient for the allowable slenderer columns. The applicability of the tabulated data for a load ratio up to 0.47 is further checked for the columns with UHSC of 120 MPa and HSS of 690 MPa, which is the strength limits recommended in AS/NZS 2327:2017.

Simplified seismic loss assessment using limit state loss-intensity models

In an effort to provide practicing engineers with simple means of limiting earthquake-induced losses to buildings, this paper extends a simplified damage-state loss vs. intensity approach for estimation of expected annual losses in two ways. Firstly, modifications to allow consideration of a threshold replacement limit state are provided. Secondly, an equation for simplified loss assessment of buildings characterised with a three-damage state loss-intensity model is presented. Furthermore, recommendations are provided for the simplified models associated parameters’ values. The proposed approach is trialled for three New Zealand code compliant eccentrically braced frame buildings, and the results compared against those obtained through the PEER framework. It is found that the expected annual loss can be predicted to within 10% of the values obtained via rigorous approaches and opportunities for further research are discussed.

Non-nutritive sweetener regulation and health: analysing applications to vary Australian and New Zealand food standards.

We aimed to understand the process of setting or varying food standards related to non-nutritive sweeteners (NNS) in Australia and New Zealand. Overconsumption of added sugars is a risk factor for non-communicable diseases. Limiting added sugar consumption is recommended by the World Health Organization. NNS are sweet substances with little to no energy that can be used to maintain the sweetness of packaged food when added sugar is reduced. The health and dietary pattern impacts of NNS are contested. Understanding how and why applications for NNS are submitted, assessed and approved within food regulatory systems is important to contextualize the increasing availability of NNS in the food supply. We completed an interpretive content analysis of applications to change the Food Standards Australia and New Zealand (FSANZ) Code, risk assessments and stakeholder submissions. Literature used in risk assessments were drawn from a mixture of documents supplied by industry and peer-reviewed studies. Risk assessments were primarily focussed on toxicological outcomes, while broader public health outcomes were not explicitly considered. Consumption data available to FSANZ were collected several years prior to dietary exposure assessments, and thus may not accurately represent current intakes. The study findings raise questions about whether the scope of what constitutes a 'risk' to public health in the setting of food standards needs to extend beyond immediate toxicological and food safety concerns, to include longer-term dietary balance considerations.

Seismic ratcheting of eccentric gravity loaded moment‐resisting frame buildings

AbstractStructures may predominantly inelastically deform in a single direction during earthquakes and incur greater damage. This behavior is known as seismic ratcheting and can be caused by eccentric gravity loads. Code clauses were introduced in Canada and New Zealand to amplify displacements obtained from static analysis methods to consider seismic ratcheting effects. However, such clauses are based on analyses of reinforced concrete (RC) wall or single‐degree‐of‐freedom (SDOF) structures, and methods to mitigate seismic ratcheting behavior were not explicitly provided. In this study, parametric analyses of steel and RC moment resisting frame buildings were performed to evaluate the adequacy of code clauses, identify parameters which influence seismic ratcheting behavior, and propose methods to mitigate such behavior. It was found that the New Zealand code underestimated the displacement increase for RC buildings, though it was able to envelope the displacement increase for steel buildings while the Canadian code was conservative. Additionally, the displacement increase was found to be sensitive to the building's post‐yield behavior and ground motion properties. However, assumptions of these properties during design may not be reflective of the actual building and seismic conditions, indicating that a reliable estimate of the increase in displacement is difficult to obtain. Instead, employing mitigation measures to reduce seismic ratcheting effects, such as designing to higher seismic demands, adding a secondary structural system to increase the building's post‐elastic stiffness, or providing more balanced lateral strengths after adjusting for eccentric gravity load effects are better measures to counter seismic ratcheting effects caused by eccentric gravity loads.

Behavior of Waste Glass Powder in Concrete Deep Beams with Web Openings

Waste Glass Powder (WGP) could be used as a cement replacement additive to manufacture concrete and solving the problem of environmental pollution. The experimental program was made up of ten simply supported reinforced High-Strength Concrete (HSC) deep beams tested under static loadings. Five beams were with WGP, while the other five beams were without WGP. Eight beams had web openings while two reference beams were without openings. The principal studied parameters were the effect of using WGP, and the location and size of web openings. Using the three-dimensional finite element computer program ABAQUS, a numerical simulation for comparing the shear strength and behavior of tested deep beams has been suggested. The comparison between experimental failure loads of studied beams with that estimated by the Strut-and-Tie model was carried out. Three codes of practice were used to make this comparison: the American Concrete Institute (ACI 318-19), the New Zealand Code (NZS-06), and the Japan Society of Civil Engineering (JSCE-07). The results showed that using WGP in similar deep beams with web openings enhances the cracking shear strength (by about 17–25%) and the ultimate shear strength (by about 12–41%). The improvement in the ultimate failure load could be attributed to the developed concrete microstructures caused by WGP’s very fine grains, producing further gel, and decreasing the number of voids in the concrete matrix. The suggested finite element simulation accurately predicts the behavior of HSC deep beams with and without WGP beams and with web openings.

Testing, modelling and design of 7A04-T6 high-strength aluminium alloy RHS columns under axial compression

The buckling behaviour and resistances of extruded 7A04-T6 high-strength aluminium alloy rectangular hollow section (RHS) columns under axial compression are reported in this paper. Nineteen RHS columns with member relative slenderness of 0.44–2.70 and cross-sections of Class 2–4 were conducted. Finite element (FE) models were developed and verified against the test failure modes, axial load-end shortening or mid-height lateral displacement curves and buckling resistances, and parametric analyses with a wide range of member and cross-section slenderness were performed. The generated test and FE results of 7A04-T6 high-strength aluminium alloy RHS columns were compared with current design methods specified in Chinese, European, American and Australian/New Zealand codes. The results indicated that the former three standards yielded conservative flexural buckling resistance predictions by about 9%, while slightly unsafe results were found for Australian/New Zealand standard, with all satisfactory reliability level. However, Chinese code resulted in the most conservative local-flexural buckling resistance predictions by about 35%, while conservative results under smaller member slenderness and overestimated ones under larger member slenderness were observed for other three standards, leading to scattered data and failing to reach target reliability indices. A series of improved design approaches shown to be safe and efficient for 7A04-T6 high-strength aluminium alloy RHS columns were suggested and validated by reliability analyses, including modified design curves for RHS columns to flexural buckling on Chinese and American standards, and three ways of proposals to imperfection terms with new coefficients as well as the direct strength method (DSM) in the framework of Chinese standard for RHS columns to local-flexural buckling.

Parametric study on cold-formed steel built-up columns using direct strength method

The use of built-up cold-formed channels in the metal lightweight industry increases for higher strengths offers in comparison with a single-channel section. However, their unavailability of design guidelines determining the axial strength had made most researchers seeking to formulate new designs rules for different built-up sections. This research aims to convey parametric study on built-up columns using a proposed Approach based on the direct strength method for further knowledge and to understand the behavior of cold-formed steel built-up columns. For that a nonlinear finite element was developed to perform a parametric study, a total of 93 finite elements models were analyzed to study the effects of the cross-section, the gap between the two channels, the spacing between battens, the addition of web stiffener, the angle variation in C-sections simple lip edge stiffener, different lengths of the profiles and the ratio (d/D), on the stability of built-up columns. An approach based on the direct strength method (DSM) was proposed, where elastic, local, distortional or global elastic buckling solutions are determined from finite element or finite strip procedures. The obtained results were compared with the current design standard the North American specifications and the Australia/New Zealand codes, the AISI specifications, and European code EC3. The results of the parametric study were compared with the values found by AISI, EC3 and proposed DSM approaches, it stated that, the design specification noted in the AISI are generally conservative for overall buckling mode and slightly conservative for local buckling mode columns. For EC3 specifications, there is a difference between open and closed sections. For open sections, the results are conservative for local buckling mode and slightly conservative for global buckling mode. For the proposed DSM approaches, the results are slightly conservative for global buckling columns and non-conservative for local buckling mode columns.

Cyclic Behavior of High-Strength Lightweight Concrete Exterior Beam-Column Connections Reinforced with GFRP

Using lightweight reinforced concrete beams with glass fiber bars (GFRP) is one approach for achieving the requirement seismic design idea of “strong-columns weak-beams”. Twelve full-scale normal-strength concrete (NC with fc` = 32 MPa) and high-strength lightweight concrete (HSLWC with fc` = 42, 49 and 52 MPa) exterior beam-column joints have been tested under cyclic loadings. The beams were reinforced with conventional steel bars (CS) and GFRP using steel fibers (SF). The experimental joint shear force was compared with that estimated by some international codes such as the American Concrete Institute (ACI-19), the Egyptian code (ECP-07), and the New Zealand Code (NZS-06). Nonlinear finite element analysis (ABAQUS) was carried out. In the present study, three main parameters were explored (1) HSLWC, (2) GFRP ratios equal to 0.70%, 1.03% and 1.37%, (3) SF ratios equal to 0.0%, 0.75% and 1.50%. The findings of the experiment revealed that increasing the concrete strength from NC with conventional steel bars to high-strength lightweight concrete HSLWC (fc` = 42 MPa) with the same ratio of GFRP bars enhanced the first cracking load by about 25%. Increasing the SF ratio to 1.50% enhanced the failure load by 18–24% when compared with non-fiber specimens. The predicted joint shear strength estimated using the equations of the ACI 318-19 and ECP-07 are conservative for HSLWC exterior beam-column connection reinforced with GFRP bars but the predicted joint shear strength by using the equations of the NZS-07 is on the borderline for some cases. The finite element program ABAQUS can be used successfully to forecast the behavior of HSLWC beam-column connections reinforced with GFRP under seismic loadings.

Cyclic behavior of high strength lightweight concrete slab-edge column connections with and without openings

In this study, the seismic behavior of nine full-scale slab-edge column connections with and without openings constructed from Normal-Strength Concrete (NSC with fc` = 28 MPa) and High-Strength Lightweight Concrete (HSLWC with fc` = 49 MPa) is investigated experimentally and analytically. The nine specimens included five specimens from NSC and four specimens from HSLWC. The punching strength provisions used by international codes, such as the International Building Code (International Code Council 2021), the American Concrete Institute (ACI Committee 318 2019), the New Zealand Code (New Zealand Standard NZS 3101: Part 1 2006), the Japan Society of Civil Engineering (JSCE 2007), and the Eurocode 2 (Eurocode 2 2008), are investigated when applied to HSLWC slab-edge column connections with openings. The most significant factors to consider are the effect of using HSLWC, the location and size of the openings. The investigation was widened by performing a nonlinear finite element analysis with the computer application ABAQUS. According to the test results, the punching shear strength estimated using the equations of the (International Code Council 2021), (ACI Committee 318 2019), (New Zealand Standard NZS 3101: Part 1 2006), and (Eurocode 2 2008) is safe for HSLWC. For both NSC and HSLWC, the punching shear strength estimated using the JSCE-2007 is either on the borderline or unsafe. The ultimate punching load of HSLWC with fc` = 49 MPa is increased by about 72% than that of NSC with fc` = 28 MPa for slab-edge column connections without openings and by approximately 81% for connections with opening size equals to one-eighth of the column strip width and positioned next to the face of the column. The finite element program ABAQUS can be used successfully to forecast the behavior of normal strength concrete and high strength lightweight concrete slab-edge column connections under seismic loadings, both with and without opening.

Design recommendations to prevent global out-of-plane instability of rectangular reinforced concrete ductile walls

Observations of out-of-plane (OOP) instability in the 2010 Chile earthquake and in the 2011 Christchurch earthquake resulted in concerns about the current design provisions of structural walls. This mode of failure was previously observed in the experimental response of some wall specimens subjected to in-plane loading. Therefore, the postulations proposed for prediction of the limit states corresponding to OOP instability of rectangular walls are generally based on stability analysis under in-plane loading only. These approaches address stability of a cracked wall section when subjected to compression, thereby considering the level of residual strain developed in the reinforcement as the parameter that prevents timely crack closure of the wall section and induces stability failure. The New Zealand code requirements addressing the OOP instability of structural walls are based on the assumptions used in the literature and the analytical methods proposed for mathematical determination of the critical strain values. In this study, a parametric study is conducted using a numerical model capable of simulating OOP instability of rectangular walls to evaluate sensitivity of the OOP response of rectangular walls to variation of different parameters identified to be governing this failure mechanism. The effects of wall slenderness (unsupported height-to-thickness) ratio, longitudinal reinforcement ratio of the boundary regions and length on the OOP response of walls are evaluated. A clear trend was observed regarding the influence of these parameters on the initiation of OOP displacement, based on which simple equations are proposed for prediction of OOP instability in rectangular walls.

Normal and High-Strength R/C Deep Beams under Pure Torsion and Codes Evaluation.(Dept.C)

Fourteen reinforced concrete deep beams were tested under pure torsion in order to evaluate the torsion design provisions of ACI 318-02 Building Code, the Egyptian code (ECCS-2001), the New Zealand code (NZS 3101-95), and the Eurocode 2 (EC-2) when applied to High Strength Concrete (HSC) deep beams. The results of these tests have been used to compare the torsional behavior of reinforced deep beams constructed from Normal-Strength Concrete (NSC with characteristic cube compressive strength fcu of about 35 MPa) and HSC (with fcu of about 81 MPa). The main parameters examined in this study were the design compressive strength, the provided transverse reinforcement ratio, the quantity of longitudinal and skin reinforcement and the size of the tested beams in the form of the tested span to total height ratio (L/h=1.0, 2.0 and 3.0). The results showed that the reserve in the torsional strength of the HSC deep beams aster cracking is considerably less than that of the similar NSC deep beams. The cracking torsional strength of the tested NSC deep beans is about 38-54% of the measured ultimate torsional strength, while the same ratio for the similar HSC deep beams is about 57-77% of the measured ultimate strength. The design torsional strength equations of the four international codes considered in this study were safe and conservative when applied to NSC and HSC deep beams. The predictions of the ultimate torsional strength of the deep beams according to the method of ACI 318-02 and using a value of the angle between the concrete struts and the longitudinal axis of the beam θ equal to 45 deg may give a conservative results less than that calculated using this angle between 30 and 60 deg.

Reliability considerations of modern design codes for CFST columns

Concrete filled steel tubular (CFST) columns have been increasingly used in tall buildings and bridges due to offering excellent structural and economic benefits. Current design codes for such columns exhibit certain limits in terms of material strengths and section slenderness. This paper aims to evaluate the reliability and the applicability of the current design equations in American code AISC 360–16, European code EC 4 and Australian/New Zealand code ASNZS 2327 for the design of the columns beyond their material and slenderness limits. A comprehensive database with over 3200 tests was collected to develop the statistics of the model errors for different types of columns. Monte Carlo and subset simulation techniques were developed based on Markov Chain Monte Carlo algorithms, to accurately and efficiently predict the reliability index of structures with small failure probability because they account for all uncertainties in material and geometric properties, loads and model errors. The results from the reliability analysis indicate that the reliability index of the concentric column designed by three considered codes is much higher than that of the eccentric column (i.e. beam-column). The results from a parametric study suggest that all three codes can be safely extended to the design of columns beyond the current material and section slenderness code limits.

Thermal monitoring of a concrete bridge in London, UK

During bridge design and assessment, effects of thermal actions are accounted for by means of a uniform temperature variation and temperature difference components. The uniform temperature variations cause changes in length and width of the structure, whereas the temperature difference components primarily cause curvatures and internal stresses. The effects of these strains on the superstructure depend on the structure's articulation and restraint. Design profiles used to model the temperature difference components vary between design codes, which can have a significant effect on the induced curvatures. Thermal data findings obtained from a comprehensive, year-long monitoring programme on Waterloo Bridge in London are examined, which allows comparison of these various models with performance data. The design thermal model in BS EN 1991-1-5 is examined, supplemented by the models from the Aashto and New Zealand codes. The measured uniform bridge temperature generally fell within the stipulated limits of BS EN 1991-1-5; however, at low temperatures the minimum deck temperature may be lower than the design relationship provided. The resultant moments implied from the measured vertical profiles: significantly exceed the worst-case values predicted by the UK model; exceed the Aashto model at different bridge sections; and do not exceed the New Zealand model.

Community pharmacists' professional practices for complementary medicines: a qualitative study in New Zealand.

Background Complementary medicines are a popular healthcare choice among patients/consumers, and most pharmacies sell these products. Pharmacists are well-placed to advise on complementary medicines, but their training and practices for these products are not optimal. Pharmacists' professional practices for complementary medicines ought to be influenced by professional codes of ethics and standards. Objective To examine community pharmacists' perspectives on complementary medicines in New Zealand, including motivations and justifications for selling these products, and professional and ethical issues complementary medicines raise for pharmacists. Setting Community pharmacists in New Zealand. Method Qualitative, semi-structured interviews with 27 New Zealand practising community pharmacists identified through purposive and convenience sampling. Main outcome measure Participants' views, experiences, and professional practices for complementary medicines. Results Participants struggled to clearly describe products they considered complementary medicines. Perspectives towards these products ranged from strongly supportive to somewhat sceptical; none was strongly opposed. Participants had several motivations for selling complementary medicines, particularly consumer demand and profits. Participants acknowledged ethical issues concerning complementary medicines, including lack of evidence of efficacy and pharmacists' limited training/knowledge. Few referred explicitly to complementary-medicines-related statements in the Pharmacy Council of New Zealand's Code of Ethics, or indicated these guided their practice. Conclusion Participants sold complementary medicines despite having limited knowledge on these products and concerns about efficacy; participants justified this as they believe they are providing an holistic option for patients, and/or ensuring complementary medicines do no harm. Participants were mindful of ethical/professional issues regarding complementary medicines, but were not necessarily aware of, or guided by, explicit statements in the Pharmacy Council of New Zealand's Code of Ethics.

Suitability of Height Amplification Factors for Seismic Assessment of Existing Unreinforced Masonry Components

ABSTRACT The suitability of ‘design’ height amplification factors (HAF) for the purpose of seismic assessment of existing non-structural unreinforced masonry (URM) components with known strength was evaluated through a numerical study. Four building typologies were included that represented pre-1940 URM construction in Australia and New Zealand. Through pushover and incremental dynamic analyses, the effects of diaphragm flexibility and nonlinear building response on floor accelerations were studied. It was found that Australia/New Zealand code procedures include significant inelastic building behaviour that reduces HAF. An interpretation was made on the applicability of the assumptions in the context of assessing non-structural URM components.

Concrete-filled steel tubular columns: Test database, design and calibration

Concrete-filled steel tubular (CFST) columns are adopted in many structural applications, especially for tall buildings, bridges and large infrastructure due to their substantial structural and economic benefits. However, the design guidelines for CFST columns with high strength materials and slender sections are still limited. In acknowledging these limitations, a large number of tests on high strength CFST columns have been conducted. In this paper, the most recent experimental data on CFST columns with high strength materials and slender sections are collected and merged with existing databases to establish a comprehensive database with over 3100 tests. The test results are then compared with those predicted from existing design codes, including Eurocode 4, Australian/New Zealand code AS/NZS 2327 and American code AISC 360-16 to calibrate their accuracy in strength prediction of CFST columns. In general, all codes give conservative predictions for CFST columns. Eurocode 4 and AS/NZS 2327 give the best predictions, whilst AISC 360-16 gives conservative predictions. The effects of material strengths and section slenderness on the code predictions are also investigated to evaluate the applicability of the codes beyond their material strength and section slenderness limits.

Towards appreciating the importance of windowscapes: Evaluation and suggestion for improvement of New Zealand Building Code

The rapid intensification of Auckland has made our visual awareness of the outdoor environment (windowscapes) more confined and restricted. The recent changes of Auckland’s windowscapes have made the shortcomings of the New Zealand Building Code more apparent. This paper aims to demonstrate the importance of windowscapes in urban dwellers’ life and suggest some changes to the current building code to provide healthier and liveable indoor environments. First, evidence from the literature on the impact of views on building occupants’ wellbeing will be reviewed. Then, New Zealand Code Clause (G7 Natural light) and its Acceptable Solution will be critically analysed to identify areas that require improvement.Our literature review indicates that private views are more relevant for health and wellbeing than building and planning legislation in New Zealand currently considers them to be. Hence, this paper suggests that windowscapes should become an essential part of future building codes and standards. This paper concludes that providing strict requirements regarding windowscapes is essential to building a healthier indoor environment.

What is meat in Australia?

• In 2014, Australia was the highest consumer of (defined as beef, pork, chicken, and lamb) in the world, consuming 90.21 kg of meat per capita per year. • The definition of in Australia is diverse and varies widely among consumers, health professionals, and regulators. • To the consumer, flesh/tissue from all living animals is considered and the most meaty to least meaty was beef/sheepmeat/ pork > chicken > hamburger/salmon/trout > crayfish > heart > kidney/liver/pig trotter > tripe/cultured meat > witchetty grub/ grasshopper/brains. Burgers made from vegetable protein were considered • From the point of view of the health professional, only red meat (muscle from beef, sheep, goat, buffalo, kangaroo, camel, deer, pig or rabbit carcasses) is considered meat, and poultry, fish, and offal (internal organs of the carcass such as brain, heart, kidney, liver, pancreas, spleen, thymus, and tripe) are considered • To the regulator, fish is not described as meat whereas all poultry and red meat is considered Food Standards Australia New Zealand (FSANZ) code classifies offal as non-meat, whereas the FSANZ Primary Production Processing Standards consider offal as meat. • It may be prudent for Australian regulators to consider standardizing their descriptions of meat. • Health professionals appear to use different definitions for compared with both consumers and regulators. This is likely because they consider any food from a nutritional point of view.

Influence of the Drag Coefficient on Communication Towers

This paper discusses some of the recent wind loading procedures for the design of lattice towers. In particular, the paper focuses the attention on the drag coefficient of communication towers with square and triangular cross-section and with flat-sided and circular elements. It provides some background behind the normative methodology of the current specialized codes and its relationship with results of experimental tests. For this purposes, different load patterns were adopted from the application of the normative methodology of the following countries: Mexico, United States, India, Japan and Australian–New Zealand Code. Additionally, the paper provides examples based on actual communication towers to illustrate the lack of consensus and to identify uncertainties in the procedures. The paper concludes that the complexity of most current wind design procedures is not justified and it pretends to help to make rational decision by designers.

Influence of base plate bending stiffness on the seismic performance of liquid storage tanks

In the past, a number of investigations have been performed on the seismic behaviour of storage tanks. At the University of Auckland, a number of shake table experiments on tanks with different aspect ratios have been recently performed. The earthquake ground excitation was simulated based on a design spectrum from the New Zealand code NZS 1170.5, classification D for soft soils. The results show that the base plate stiffness of storage tanks may play a significant role in the magnitude of hoop stresses caused by the passage of the earthquake. To incorporate a low-damage seismic design philosophy, the tank is allowed to separate partially at the base. This temporary separation initiates rigid body like motion of the tank and thus reduce the wall local deformations. Consequently, the stress development along the wall can be reduced from that occurring with full base plate contact. This research focuses on the effect of the base plate thickness on the hoop stress development along the height of the tank wall for five radial directions.