Papers by Charles Clifton
Bulletin of Earthquake Engineering
A finite element numerical model is used to estimate the force displacement backbone curve of ste... more A finite element numerical model is used to estimate the force displacement backbone curve of steel moment frame beam-column-joint subassemblies tested at large scale under repeated cyclic loading with different composite deck slab configurations. The slab configurations included: no-slab; fully isolated slab; two configurations for detailing the slab near the region between the column flanges; and a full depth reinforced slab. Then, a simple analytical model was developed so that designers can estimate the likely peak strength due to slab effect. This analytical model considers the common deformation modes and the strength hierarchy. It was found that the finite element numerical model captured the backbone envelope of experimental tests done on different slab configurations for the bare frame, isolated slab and full depth slab configurations, but overestimated the strength at larger displacements for the other configurations due to difficulty in considering the slab modes of failu...
Earthquake Engineering & Structural Dynamics, 2014
The Asymmetric Friction Connection (AFC) remains elastic during moderate earthquake shaking but s... more The Asymmetric Friction Connection (AFC) remains elastic during moderate earthquake shaking but slides and dissipates energy through friction during severe earthquake shaking. The sliding friction forces developed are dependent on the clamping force in the connection which is provided by fully tensioned bolts which pass through slotted holes. During sliding these bolts are subject to moment and shear as well as axial force. Moment-shear-axial force interaction reduces the clamping axial force on the sliding interfaces thereby reducing the sliding shear resistance (V ss). Two methods to evaluate the moment-shear-axial force interaction have been proposed so that the sliding shear strength can be quantified, but as yet, these methods are not robust. This paper describes the results of 60 tests undertaken to improve the two methods, namely the moment-shear-axial force bolt model and the effective coefficient of friction method, for AFCs with high hardness steel shims. The bolts were M16 to M30 bolts and cleat thicknesses ranged from 12 mm to 25 mm. It is shown that either method may be used in design as the results obtained are similar.
Journal of Constructional Steel Research, 2012
The Sliding Hinge Joint is a beam-column connection used in low damage moment-resisting steel fra... more The Sliding Hinge Joint is a beam-column connection used in low damage moment-resisting steel frames. It allows inelastic deformation with small but significant losses of elastic strength and stiffness during a major earthquake, and does not always return the joint and overall building to the pre-earthquake position. It thus does not fulfil the optimum requirement of no maintenance. This paper presents the ongoing development of a damage free self-centering Sliding Hinge Joint utilising friction Ring Springs. This work has commenced with tests to determine (1) the effects of steel shims of different hardness on the sliding behaviour, (2) the adequacy of the bolt model previously developed for the SHJ, and (3) the residual joint strength of the postearthquake joint. The abrasion resistant Grade 400 plate, the hardest steel considered, generated the largest sliding shear capacity, and the most stable sliding characteristics. It is therefore recommended for use in future SHJ construction. The bolt capacities and residual joint strengths are affected by bolt size, length of bolt lever arm and presence of Belleville Springs. These effects are not yet fully understood at the time of writing. More tests of various specimen sizes will be used to develop a more accurate model.
Journal of Constructional Steel Research, 2012
ABSTRACT The Sliding Hinge Joint is a flexural connection designed for use at the ends of beams i... more ABSTRACT The Sliding Hinge Joint is a flexural connection designed for use at the ends of beams in steel moment resisting frames. It is an asymmetric friction connection, where energy is dissipated through sliding in slotted bolted connections in the beam bottom flange. The friction resistance and the repeatability of the hysteretic force displacement curves are dependent on the type of shim used. Brass or mild steel shims have been researched and used in construction to date. This paper describes tests on the sliding components conducted to investigate the use of steel shims of different hardness. The materials tested were mild steel, high strength quenched and tempered steel, and abrasion resistant steel. The beam and cleats which these shims slid against were Grade 300 mild steel. The specimens were tested dynamically at earthquake rates of loading. The abrasion resistant steel, the hardest material, produced the most stable and consistent sliding characteristics for all displacement cycles on different specimens. It also had the least material wear and the highest friction capacity per bolt. Compared to brass, high strength steels are more readily available, less costly, more easily erected, and less susceptible to corrosion, making them a preferred solution.
European Journal of Mechanics - A/Solids, 2011
The buckling problem of an infinite thin plate resting on a tensionless Winkler foundation and su... more The buckling problem of an infinite thin plate resting on a tensionless Winkler foundation and subjected to shearing loads is investigated. The infinite plate is simplified to a one-dimensional mechanical model by assuming a lateral buckling mode function and a borderline function between contact and noncontact regions. After the governing differential equations for the plate sections in the contact and non-contact regions have been solved, the problem reduces to two nonlinear algebraic equations. Buckling coefficients for plates with simply supported edges and clamped edges are determined for a range of relative foundation stiffness factors. Comparison of the results with existing theory and finite element analyses shows good agreement.
Braces equipped with Asymmetrical Friction Connection (AFC) details, assembled with Bisalloy 500 ... more Braces equipped with Asymmetrical Friction Connection (AFC) details, assembled with Bisalloy 500 shims and placed at one end of the braces, have been tested quasi-statically. It is shown that braces equipped with AFC details are characterized by a repeatable hysteretic behaviour with strength degradations up to 10%. This degradation corresponds to the case where braces are subjected up to 40 cycles across the effective stroke of the connection with no components replaced or bolts re-tensioning. Also, outof-plane brace deformation slightly causes a change in strength with axial displacement. Effective friction coefficients ranging between 0.16 and 0.20 were obtained for AFC braces.
Automating regulatory compliance audit in the Architecture, Engineering and Construction domain h... more Automating regulatory compliance audit in the Architecture, Engineering and Construction domain has been subject of considerable research, but has no viable solution. The main challenge is the continued practice of paper-based information exchange in the industry. The emergence of an ISO standard Building Information Model (BIM) to represent buildings as semantically rich objects has the potential to address part of the problem. However, it must be coupled with an efficient and practical computable representation of the regulatory knowledge, and an automated system to process them for compliance audit. Objectives 1. To develop a practical computerised representation of performance-based codes with an application to the fire safety design of buildings in New Zealand. 2. To implement an effective method of extracting information from ISO standard BIM-based models. 3. To develop a framework that could process the building model and the regulatory knowledge base to support automated per...
Computer-aided compliance auditing aims to provide an automated system to assess engineering desi... more Computer-aided compliance auditing aims to provide an automated system to assess engineering designs against specified regulatory representations. Previous research has largely focused on prescriptive regulatory rules, which are relatively easier to audit than those pertaining to performance-based codes with qualitative criteria. There have been a few prototype implementations of rule-based compliance auditing systems that tend to represent regulatory knowledge as complex rule sets integrated into the system. The drawback of this approach is inflexibility, relatively high costs and dependency on the system programmer to modify built-in rules in response to on-going regulatory amendments. The current research looks at representing regulatory knowledge as a library of compliant design procedures (CDP) and the associated regulatory rules, which are treated as external input components to the system. This would allow them to be managed and maintained independently by designers and regul...
A single storey moment resisting frame with one bay and equipped with a concentric AFC brace was ... more A single storey moment resisting frame with one bay and equipped with a concentric AFC brace was tested. The asymmetrical friction connection brace (AFC brace) was assembled using one 250PFC channel, two Bisalloy 500 shims, and two M16 Grade 8.8 galvanized bolts. Results show that by introducing the AFC brace, the frame can undergo drifts up to 3.0% without yielding any frame member or component, and more importantly with low degradation on the AFC detail. Results also show that the amount of load that the frame can absorb during a seismic event can be controlled by the AFC brace strength.
Multi-storey modular construction has rapidly been gaining popularity globally over recent years,... more Multi-storey modular construction has rapidly been gaining popularity globally over recent years, but is currently limited in high seismic regions such as NZ due to the need for a separate seismic-resisting system to prevent severe damage to the bottom level of modules. A PhD research project has been undertaken with a focus on the development of a passive energy-dissipating slider device for damage-resistant seismic protection of multi-storey modular buildings. Experimental and numerical studies have been undertaken on the system incorporating the proposed slider devices in threeand six-storey modular steel structures. It has been demonstrated through these studies that the performance of the sliding system is satisfactory.
An extensive parametric study of cold-formed ferritic stainless steel unlipped channels with fast... more An extensive parametric study of cold-formed ferritic stainless steel unlipped channels with fastened flanges subjected to web crippling under end-two-flange (ETF) loading condition is undertaken, using quasi-static finite element analysis, to investigate the effects of web holes and cross-sections sizes. Both cases of unlipped channels with and without web holes are considered. The web holes are located either centred or offset to the load and reaction plates. It is noted that no cold-formed stainless steel standard provides capacity reduction factors for unlipped channels with fastened flanges subject to end-two-flange loading condition. The strengths obtained from reduction factor equations are first compared to strengths calculated from equations recently proposed for cold-formed stainless steel lipped channels. It is demonstrated that the strength reduction factor equations previously proposed for cold-formed stainless steel lipped channels can be unconservative for cold-formed...
The Robust Building Systems (ROBUST) project is aimed at enhancing the seismic resilience of buil... more The Robust Building Systems (ROBUST) project is aimed at enhancing the seismic resilience of buildings by introducing and validating low-damage concepts for the structural and non-structural elements (NSEs). A three-story, full-scale, structural steel building will be tested at the International Joint Research Laboratory of Earthquake Engineering (ILEE) at Tongji University, under uniaxial and biaxial shaking. This project includes an objective and detailed plan for testing acceleration and drift-sensitive non-structural elements encompassing typical New Zealand design and construction practices along with some lowdamage concepts. A total of five NSEs will be included in the test: 1) suspended ceilings, 2) partitions walls, 3) precast cladding panels, 4) glazing, and 5) fire sprinkler piping systems. Partitions walls, being driftsensitive, will be installed on the first & second floor of the test structure, whereas suspended ceilings and fire sprinkler piping systems, being accelera...
Web holes are commonly used in beams of buildings to facilitate services. In this paper, a combin... more Web holes are commonly used in beams of buildings to facilitate services. In this paper, a combination of tests and nonlinear finite element analyses is used to investigate the effect of such web holes on the web crippling strength of coldformed ferritic stainless steel unlipped channels under the end-two-flange (ETF) loading condition; the case of flanges fastened to the load and reaction plates is considered. The results of 27 web crippling tests are presented, with 9 tests conducted on unlipped channels without web holes and 18 tests conducted on unlipped channels with web holes. In the case of tests with web holes, the holes are located either centred or offset to the load and reaction plates. A quasi-static finite element model is then presented. Good agreement between the tests and finite element analyses is obtained in terms of failure load, failure modes and post-buckling behaviour.
The use of high-strength, cold-formed steel frames in residential construction is steadily increa... more The use of high-strength, cold-formed steel frames in residential construction is steadily increasing in both Australia and New Zealand. One common form of this construction uses brick veneer as a cladding, where non-structural brick walls are attached to the structural frame via brick ties. Under earthquake loading there is a complex interaction between the frame and veneer walls. While there is a standard component test method for assessing the seismic capacity of brick ties, this method has been developed around brick veneer on timber studs and its application to the very different steel stud characteristics is inappropriate. In order to realistically assess the overall performance of brick veneer construction with steel framing, a full scale one-room test structure "Test House" was tested on a shaking table. The Test House incorporated veneer walls with different geometries. It was subjected to varying levels of the El Centro earthquake ranging from moderate serviceabi...
Proceedings of the 4th International Conference on Civil, Structural and Transportation Engineering (ICCSTE'19), Jun 1, 2019
This paper shows an overview understanding of building codes practice in different countries acro... more This paper shows an overview understanding of building codes practice in different countries across the globe. Approach to building code practice and updates differs from country to country, but its primary aim is to provide the minimum requirements to protect life and properties in the built environment. The building code philosophy is to avoid collapse during and after an earthquake and other related extreme loading conditions. The data approach for this study was from the secondary source. This review aims to examine the paradigm shift in building code practice across different nations to determine which countries are embracing performance-based regulation through efficient building code improvement. The paper lays out performance base approach status, mode of compliance, amendment interval, issues that necessitates updates, implementation, code enforcement and highlight some challenges that need to be overcome to harness the full potentials of the innovative building code practice. The study provided a better understanding of comparative insights into the various building code in the selected countries and the factors that encouraged the paradigm shift in building code to accommodate technological innovation in the construction industry. The paper showed that many developed and developing countries are gradually shifting from prescriptive-based code to performance-based building code due to innovation, economic boom on infrastructure and persistent disaster occurrence in the built environment.
Composite Construction in Steel and Concrete VII, 2016
This paper describes the effect of composite slabs in increasing beam strength and its implicatio... more This paper describes the effect of composite slabs in increasing beam strength and its implications for design. It also discusses the "beam-growth" phenomena, which can detrimentally influence the performance of a frame with reinforced concrete or precast concrete beams, and its impact on steel beams with RC slabs. From the subassembly testing conducted the slab increased the beam strength by around 40%. However the slab could not maintain strength at large drifts without degradation with transverse or longitudinal decking placed around the columns. This indicates that while transverse or longitudinal slabs should not be considered in design to size the beam, they should be considered in the beam overstrength calculations for the design of other members. Also, both rational considerations and experimental results
Journal of Computing in Civil Engineering, 2016
Two common challenges in the computer-aided compliance audit of building engineering designs are ... more Two common challenges in the computer-aided compliance audit of building engineering designs are being addressed in the current research. The first is to ensure that any form of computable representation is practical and relatively easy to use and maintain. The second is to ensure that performance-based regulatory compliance criteria, which are often qualitative in nature, are adequately addressed and correctly represented. This research proposes a method of automating manual compliant design procedures using an open standard executable workflow representation that can be specified and maintained relatively easily by a design engineer. This executable workflow is referred to as the Compliant Design Procedure (CDP) and can be described graphically using a subset of the open standard Business Process Model and Notation (BPMN). When executed in a computing environment, a CDP can guide the compliance audit process by checking a given design represented in a model view or subset of the BIM model, referred to as the Building Compliance Model (BCM), against the criteria in a digital building code, referred to as the Regulatory Knowledge Model (RKM), which is developed specifically for this purpose. This paper describes the process of modelling and encoding BCM, CDP and RKM, which are independent input components of the proposed compliance audit system framework. Supplementary human input and the ability to exchange input and output data with external simulation tools to solve some of the more complex qualitative criteria are important features of the framework.
The main challenges in automating the regulatory compliance checking of building engineering desi... more The main challenges in automating the regulatory compliance checking of building engineering designs are the availability of computable representations of the building and the regulatory knowledge, as well as a system that can process and manage these representations effectively. The emergence of Building Information Modelling (BIM) and Industry Foundation Classes (IFC) at the start of the millennium has sparked useful research in the area of sharing building information effectively, but challenges remain with producing a practical and manageable regulatory knowledge representation that can be processed effectively by a compliance checking system. Research is being conducted to develop a two-part regulatory knowledge representation, which can be maintained independently by designers and regulators. One part is a set of compliant design procedures modelled as Business Process Diagrams (BPD) using an open standard Business Process Model and Notation (BPMN), and the other is the associ...
Lessons learned from the 2010/2011 Christchurch earthquake sequence about the behaviour of steel ... more Lessons learned from the 2010/2011 Christchurch earthquake sequence about the behaviour of steel structures are described. Firstly, observed performance of steel structures is summarised. It is shown that many steel structures had very little damage. However, some structures suffered damage as a result of large foundation settlements. Yielding, buckling and fractures were observed in steel bridges and buildings. Reasons for observed damage are then described in the light of recent studies. It is shown that because of the lesser damage to steel structures and greater uncertainty over repair of reinforced concrete structures, that steel structures have become popular in the Christchurch rebuild. A number of these use low-damage systems.
The ingredients for an effective automated audit of a building design include a BIM model contain... more The ingredients for an effective automated audit of a building design include a BIM model containing the design information, an electronic regulatory knowledge model, and a practical method of processing these computerised representations. There have been numerous approaches to computer-aided compliance audit in the AEC/FM domain over the last four decades, but none has yet evolved into a practical solution. One reason is that they have all been isolated attempts that lack any form of standardisation. The current research project therefore focuses on using an open standard regulatory knowledge and BIM representations in conjunction with open standard executable compliant design workflows to automate the compliance audit process. This paper provides an overview of different approaches to access information from a regulatory model representation. The paper then describes the use of a purpose-built high-level domain specific query language to extract regulatory information as part of t...
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Papers by Charles Clifton