164 results for Dhakal, R.P.

  • Seismic fragility of suspended ceiling systems used in NZ based on component tests

    Dhakal, R.P.; MacRae, G.A.; Pourali, A.; Paganotti, G. (2016)

    Journal Articles
    University of Canterbury Library

    Current standards and guidelines for the design and installation of perimeter-fixed suspended ceilings are briefly reviewed and a summary of common damage in recent earthquakes is provided. Component failure fragility curves have been derived following experiments on typical NZ suspended ceilings, considering loading in tension, compression and shear. A simple method to analyse perimeter-fixed ceilings using peak floor acceleration (PFA) is described, allowing for ceiling system fragility to be obtained from component fragilities. This is illustrated in an example of a 5 storey building. It was found that single rivet end-fixings and cross-tee connections were the most critical elements of the ceilings governing the system capacity. In the design examples it was shown that ceilings at different elevations of the structure showed different probabilities of failure and larger ceiling areas with heavier tiles were most susceptible to damage.

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  • Seismic Performance of Existing New Zealand Shear Wall Structures

    Dashti, F.; Dhakal, R.P.; Pampanin, S. (2015)

    Conference Contributions - Other
    University of Canterbury Library

    Assessment of the structural performance of existing buildings requires a better understanding of seismic performance of the structural components designed according to different versions of design codes. This study provides a summary of the evolution of the reinforced concrete wall design provisions in New Zealand, and investigates their effect on seismic performance of structural walls. For this purpose, a typical rectangular wall is designed according to different versions of New Zealand concrete design standards, and a finite element approach is used for numerical simulation of the walls subject to cyclic loading. The modeling approach has been verified using experimental results of walls with different shear-span ratios which failed in different modes. Performance of the designed wall models is investigated in terms of failure pattern, drift capacity and displacement as well as curvature ductility. Seismic performance of the walls designed according to the previous versions of NZ design codes will provide a considerable contribution to better understanding of the wall capacity in seismic assessment of existing buildings.

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  • The history of design guidelines and details of reinforced concrete column in New Zealand

    Niroomandi, A.; Pampanin, S.; Dhakal, R.P. (2015)

    Conference Contributions - Published
    University of Canterbury Library

    Existing New Zealand (NZ) building stock contains a significant number of structures designed prior to 1995 with non-ductile reinforced concrete (RC) columns. Recent earthquakes and research show that columns with such details perform poorly when subjected to seismic demand, losing gravity load carrying capacity at drift levels lower than the expected one. Therefore, in order to have a better understanding of existing RC columns in NZ, the history of these elements is investigated in this paper. The evolution of RC column design guidelines in NZ standards since the 1970s is scrutinized. For this purpose, a number of RC columns from Christchurch buildings built prior to 1995 are assessed using the current code of practice.

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  • Incremental fire analysis (IFA) for probabilistic fire risk assessment

    Moss, P.J.; Abu, A.K.; Dhakal, R.P. (2014)

    Conference Contributions - Published
    University of Canterbury Library

    In this paper, the concept of a probabilistic fire risk analysis method is presented in line with the seismic risk assessment approach. The probabilistic fire risk assessment approach runs through a series of probabilistic interrelationships between different variables representing the fire severity (called the Intensity Measure IM), structural response (called the Engineering Damage Parameter EDP) and damage/loss (called the Damage Measure DM). The paper explains the development of a probabilistic interrelationship between the IM and EDP through incremental fire analysis (IFA). For this purpose, a series of SAFIR analysis of a simple two span reinforced concrete beam subjected to different fire profiles have been conducted and are used to illustrate the required approach. Although a single EDP (maximum deflection) is considered in this investigation, two different IMs (maximum temperature and total radiant heat energy) are used. It is found that the radiant energy is more efficient than the maximum temperature in representing the fire severity.

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  • Feasibility of pinned-base connections for demountable precast frame building systems

    Aninthaneni, P.K.; Dhakal, R.P.; Marshall, J. (2014)

    Conference Contributions - Published
    University of Canterbury Library

    In recent Canterbury earthquakes, structures have performed well in terms of life safety but the estimated total cost of the rebuild was as high as $40 billion. The major contributors to this cost are repair/demolition/rebuild cost, the resulting downtime and business interruption. For this reason, the authors are exploring alternate building systems that can minimize the downtime and business interruption due to building damage in an earthquake; thereby greatly reducing the financial implications of seismic events. In this paper, a sustainable and demountable precast reinforced concrete (RC) frame system in which the precast members are connected via steel tubes/plates or steel angles/plates and high strength friction grip (HSFG) bolts is introduced. In the proposed system, damaged structural elements in seismic frames can be easily replaced with new ones; thereby making it an easily and quickly repairable and a low-loss system. The column to foundation connection in the proposed system can be designed either as fixed or pinned depending on the requirement of strength and stiffness. In a fixed base frame system, ground storey columns will also be damaged along with beams in seismic events, which are to be replaced after seismic events; whereas in a pin base frame only beams (which are easy to replace) will be damaged. Low to medium rise (3-6 storey) precast RC frame buildings with fixed and pin bases are analyzed in this paper; and their lateral capacity, lateral stiffness and natural period are scrutinized to better understand the pros and cons of the demountable precast frame system with fixed and pin base connections.

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  • Seismic design of buildings: Looking towards the future

    Dhakal, R.P. (2014)

    Conference Contributions - Other
    University of Canterbury Library

    In the last century, seismic design has undergone significant advancements. Starting from the initial concept of designing structures to perform elastically during an earthquake, the modern seismic design philosophy allows structures to respond to ground excitations in an inelastic manner, thereby allowing damage in earthquakes that are significantly less intense than the largest possible ground motion at the site of the structure. Current performance-based multi-objective seismic design methods aim to ensure life-safety in large and rare earthquakes, and to limit structural damage in frequent and moderate earthquakes. As a result, not many recently built buildings have collapsed and very few people have been killed in 21st century buildings even in large earthquakes. Nevertheless, the financial losses to the community arising from damage and downtime in these earthquakes have been unacceptably high (for example; reported to be in excess of 40 billion dollars in the recent Canterbury earthquakes). In the aftermath of the huge financial losses incurred in recent earthquakes, public has unabashedly shown their dissatisfaction over the seismic performance of the built infrastructure. As the current capacity design based seismic design approach relies on inelastic response (i.e. ductility) in pre-identified plastic hinges, it encourages structures to damage (and inadvertently to incur loss in the form of repair and downtime). It has now been widely accepted that while designing ductile structural systems according to the modern seismic design concept can largely ensure life-safety during earthquakes, this also causes buildings to undergo substantial damage (and significant financial loss) in moderate earthquakes. In a quest to match the seismic design objectives with public expectations, researchers are exploring how financial loss can be brought into the decision making process of seismic design. This has facilitated conceptual development of loss optimisation seismic design (LOSD), which involves estimating likely financial losses in design level earthquakes and comparing against acceptable levels of loss to make design decisions (Dhakal 2010a). Adoption of loss based approach in seismic design standards will be a big paradigm shift in earthquake engineering, but it is still a long term dream as the quantification of the interrelationships between earthquake intensity, engineering demand parameters, damage measures, and different forms of losses for different types of buildings (and more importantly the simplification of the interrelationship into design friendly forms) will require a long time. Dissecting the cost of modern buildings suggests that the structural components constitute only a minor portion of the total building cost (Taghavi and Miranda 2003). Moreover, recent research on seismic loss assessment has shown that the damage to non-structural elements and building contents contribute dominantly to the total building loss (Bradley et. al. 2009). In an earthquake, buildings can incur losses of three different forms (damage, downtime, and death/injury commonly referred as 3Ds); but all three forms of seismic loss can be expressed in terms of dollars. It is also obvious that the latter two loss forms (i.e. downtime and death/injury) are related to the extent of damage; which, in a building, will not just be constrained to the load bearing (i.e. structural) elements. As observed in recent earthquakes, even the secondary building components (such as ceilings, partitions, facades, windows parapets, chimneys, canopies) and contents can undergo substantial damage, which can lead to all three forms of loss (Dhakal 2010b). Hence, if financial losses are to be minimised during earthquakes, not only the structural systems, but also the non-structural elements (such as partitions, ceilings, glazing, windows etc.) should be designed for earthquake resistance, and valuable contents should be protected against damage during earthquakes. Several innovative building technologies have been (and are being) developed to reduce building damage during earthquakes (Buchanan et. al. 2011). Most of these developments are aimed at reducing damage to the buildings’ structural systems without due attention to their effects on non-structural systems and building contents. For example, the PRESSS system or Damage Avoidance Design concept aims to enable a building’s structural system to meet the required displacement demand by rocking without the structural elements having to deform inelastically; thereby avoiding damage to these elements. However, as this concept does not necessarily reduce the interstory drift or floor acceleration demands, the damage to non-structural elements and contents can still be high. Similarly, the concept of externally bracing/damping building frames reduces the drift demand (and consequently reduces the structural damage and drift sensitive non-structural damage). Nevertheless, the acceleration sensitive non-structural elements and contents will still be very vulnerable to damage as the floor accelerations are not reduced (arguably increased). Therefore, these concepts may not be able to substantially reduce the total financial losses in all types of buildings. Among the emerging building technologies, base isolation looks very promising as it seems to reduce both inter-storey drifts and floor accelerations, thereby reducing the damage to the structural/non-structural components of a building and its contents. Undoubtedly, a base isolated building will incur substantially reduced loss of all three forms (dollars, downtime, death/injury), even during severe earthquakes. However, base isolating a building or applying any other beneficial technology may incur additional initial costs. In order to provide incentives for builders/owners to adopt these loss-minimising technologies, real-estate and insurance industries will have to acknowledge the reduced risk posed by (and enhanced resilience of) such buildings in setting their rental/sale prices and insurance premiums.

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  • Simplified Seismic Loss Functions for Suspended Ceilings and Drywall Partitions

    Dhakal, R.P.; Pourali, A.; Saha, S. (2016)

    Journal Articles
    University of Canterbury Library

    Post-disaster reconnaissance reports frequently list non-structural components (NSCs) as a major source of financial loss in earthquakes. Moreover, minimizing their damage is also of vital significance to the uninterrupted functionality of a building. For efficient decision making, it is important to be able to estimate the cost and downtime associated with the repair of the damage likely to be caused at different hazard levels used in seismic design. Generalized loss functions for two important NSCs commonly used in New Zealand, namely suspended ceilings and drywall partitions are developed in this study. The methodology to develop the loss functions, in the form of engineering demand parameter vs. expected loss due to the considered components, is based on the existing framework for the storey level loss estimation. Nevertheless, exhaustive construction/field data are employed to make these loss functions more generic. In order to estimate financial losses resulting from the failure of suspended ceilings, generalized ceiling fragility functions are developed and combined with the cost functions, which give the loss associated with typical ceilings at various peak acceleration demands. Similarly, probabilities of different damage states in drywall partitions are combined with their associated repair/replacement costs to find the cumulative distribution of the expected loss due to partitions at various drift levels, which is then normalized in terms of the total building cost. Efficiencies of the developed loss functions are investigated through detailed loss assessment of case study reinforced concrete (RC) buildings. It is observed that the difference between the expected losses for ceilings, predicted by the developed generic loss function, and the losses obtained from the detailed loss estimation method is within 5%. Similarly, the developed generic loss function for partitions is able to estimate the partition losses within 2% of that from the detailed loss assessment. The results confirm the accuracy of the proposed generic seismic loss functions.

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  • Beyond ductility: parametric testing of a jointed rocking beam-column connection designed for damage avoidance

    Rodgers, G.W.; Mander, J.B.; Chase, J.G.; Dhakal, R.P. (2016)

    Journal Articles
    University of Canterbury Library

    Despite their good performance in terms of their design objectives, many modern code-prescriptive buildings built in Christchurch, New Zealand had to be razed after the 2010-2011 Canterbury earthquakes because repairs were deemed too costly due to widespread sacrificial damage. Clearly a more effective design paradigm is needed to create more resilient structures. Rocking, post-tensioned connections with supplemental energy dissipation can contribute to a damage avoidance designs (DAD). However, few have achieved all three key design objectives of damage-resistant rocking, inherent recentering ability, and repeatable, damage-free energy dissipation for all cycles, which together offer a response which is independent of loading history. Results of experimental tests are presented for a near full-scale rocking beam-column sub-assemblage. A matrix of test results is presented for the system under varying levels of posttensioning, with and without supplemental dampers. Importantly, this parametric study delineates each contribution to response. Practical limitations on posttensioning are identified: a minimum to ensure static structural re-centering, and a maximum to ensure deformability without threadbar yielding. Good agreement between a mechanistic model and experimental results over all parameters and inputs indicates the model is robust and accurate for design. The overall results indicate that it is possible to create a DAD connection where the non-linear force-deformation response is loading history independent and repeatable over numerous loading cycles, without damage, creating the opportunity for the design and implementation of highly resilient structures.

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  • Seismic loss optimization of frame buildings using viscous dampers

    Puthanpurayil, A.; Lavan, O.; Dhakal, R.P. (2015)

    Conference Contributions - Published
    University of Canterbury Library

    The effectiveness of control strategies in achieving the objectives of a performance-based-design is well accepted in the earthquake engineering community. Consequently, various methods have been proposed for optimal design of dampers and their distribution along the building height. Most of the formulated methods concentrate mainly on reducing the responses with no explicit consideration of their long-term economic impact. In this study, an optimization problem is formulated for optimally distributing viscous dampers by minimizing the initial cost subject to a constraint on the total expected seismic loss. An intensity based assessment is used for the computation of the total expected loss. A generic Sequential Linear Programming procedure is employed to solve the formulated optimization problem. Implementation scheme of the optimization procedure is outlined in detail. The efficacy of the proposed procedure is illustrated by applying it on a four story reinforced concrete frame. It has been shown that the optimization procedure results in the optimal quantity and distribution of viscous dampers along the height of the case study building.

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  • Analytical Simulation of Seismic Collapse of RC Frame Buildings

    Ebrahimi Koopaee, M.; Dhakal, R.P.; MacRae, G.A. (2015)

    Journal Articles
    University of Canterbury Library

    Application of a fibre-element nonlinear modelling technique for seismic collapse capacity assessment of RC frame buildings in comparison with conventional lumped plasticity models is investigated in this paper. Constitutive material models of concrete and steel for fibre elements are adopted to enable simulation of the loss in vertical load carrying capacity of structural columns. Inclusion of the nonlinear second order ?−Δ effects accelerated by degrading behaviour of steel and concrete materials in the fibre model allows prediction of the sidesway mode of collapse. The model is compared with nonlinear lumped plasticity models in which stiffness and strength degradation is replicated through degrading parameters in structural components. Static cyclic analyses of an example cantilever column and a portal frame indicate that the variation of axial loads in columns may result in accelerated degradation and failure of structural components which is not taken into account by lumped plasticity models. Moreover, incremental dynamic analysis of a ten-storey RC frame shows that the lumped plasticity model may overestimate building collapse capacity when vertical failure of structural components occurs prior to sidesway instability.

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  • Using High-Strength Self-Compacting Concrete in Reinforced Concrete Beam-Column Joints

    Soleymani Ashtiani, M.; Dhakal, R.P.; Scott, A.N. (2013)


    University of Canterbury Library

    The capability of self-compacting concrete (SCC) in flowing through and filling in even the most congested areas makes it ideal for being used in congested reinforced concrete (RC) structural members such as beam-column joints (BCJ). However, members of tall multi-storey structures impose high capacity requirements where implementing normal-strength self-compacting concrete is not preferable. In the present study, a commercially reproducible high-strength self-compacting concrete (HSSCC), a conventionally vibrated high-strength concrete (CVHSC) and a normal strength conventionally vibrated concrete (CVC) were designed using locally available materials in Christchurch, New Zealand. Following the guidelines of the New Zealand concrete standards NZS3101, seven beam-column joints (BCJ) were designed. Factors such as the concrete type, grade of reinforcement, amount of joint shear stirrups, axial load, and direction of casting were considered variables. All BCJs were tested under a displacement-controlled quasi-static reversed cyclic regime. The cracking pattern at different load levels and the mode of failure were also recorded. In addition, the load, displacement, drift, ductility, joint shear deformations, and elongation of the plastic hinge zone were also measured during the experiment. It was found that not only none of the seismically important features were compromised by using HSSCC, but also the quality of material and ease of construction boosted the performance of the BCJs.

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  • Cyclic beam bending test for assessment of bond-slip behavior

    Soleymani Ashtiani, M.; Dhakal, R.P.; Scott, A.N.; Bull, D.K. (2012)


    University of Canterbury Library

    Bond between reinforcement and concrete is one of the most important aspects in structural response of reinforced concrete (RC) members. Basic RC theories assume compatibility of strains between concrete and steel which is valid only if a perfect bond exists between the two materials. Therefore investigating bond properties under different loading conditions and considering various variables is of great importance. Although researchers have extensively explored bond-slip relationships for different concrete and steel types under monotonic loading using different test setups, less is reported on bond properties under reversed cyclic loading. Modified pullout tests have previously been used to investigate cyclic bond-slip relationships; nevertheless these tests do not represent the actual bond behaviour inside RC members subjected to flexural actions. This study focuses on developing a specific test setup and designing a beam specimen for cyclic bond test following RILEM recommendations for monotonic assessment of bond properties, which require a two-point loading (four-point bending) setup. The main challenge was to design a stable cyclic test setup in order to ensure no additional forces generated in the system during the test. High strength self-compacting concrete (HSSCC) beam specimens were chosen for the test; the beam specimens were designed in such a way that they could withstand load reversals.

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  • Seismic performance of high-strength self-compacting concrete in reinforced concrete beam-column joints

    Soleymani Ashtiani, M.; Dhakal, R.P.; Scott, A. N. (2012)


    University of Canterbury Library

    Beam-column joints of reinforced concrete building frames play an important role under seismic excitations. These are one of the most congested areas in reinforced concrete framed structures; placement of concrete and proper compaction in such areas are hence substantially challenging. This offers a unique area of application for self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration. Therefore if implementing self-compacting concrete in beam-column joints does not compromise seismic performance of the frame, it can be used instead of conventional concrete. This paper focuses on implementation of high-strength self-compacting concrete in beam-column joints and assessment of its seismic behaviour under reversed cyclic loading. Three interior beam-column subassemblies chosen to vary in concrete type and compressive strength are designed as per the New Zealand Standard NZ3101:2006. The specimens are instrumented to measure the load, displacement/drift, ductility, joint shear deformations, and elongation of the plastic hinge zone. The cracking pattern at different load levels and the mode of failure are also recorded and compared among different specimens.

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  • Building pounding damage observed in the 2011 Christchurch earthquake

    Cole, G.; Dhakal, R.P.; Chouw, N. (2012)


    University of Canterbury Library

    This paper describes the pounding damage sustained by buildings in the February 2011 Christchurch earthquake. Approximately 6% of buildings in Christchurch CBD were observed to have suffered some form of serious pounding damage. Typical and exceptional examples of building pounding damage are presented and discussed. Almost all building pounding damage occurred in unreinforced masonry buildings, highlighting their vulnerability to this phenomenon. Modern buildings were found to be vulnerable to pounding damage where overly stiff and strong ‘flashing’ components were installed in existing building separations. Soil variability is identified as a key aspect that amplifies the relative movement of buildings, and hence increases the likelihood of pounding damage. Building pounding damage is compared to the predicted critical pounding weaknesses that have been identified in previous analytical research.

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  • Cyclic beam bending test for assessment of bond-clip behavior

    Ashtiani, M.S.; Dhakal, R.P.; Scott, A.; Bull, D.K. (2012)


    University of Canterbury Library

    Bond between reinforcement and concrete is one of the most important aspects in structural response of reinforced concrete (RC) members. Basic RC theories assume compatibility of strains between concrete and steel which is valid only if a perfect bond exists between the two materials. Therefore investigating bond properties under different loading conditions and considering various variables is of great importance. Although researchers have extensively explored bond-slip relationships for different concrete and steel types under monotonic loading using different test setups, less is reported on bond properties under reversed cyclic loading. Modified pullout tests have previously been used to investigate cyclic bond-slip relationships; nevertheless these tests do not represent the actual bond behaviour inside RC members subjected to flexural actions. This study focuses on developing a specific test setup and designing a beam specimen for cyclic bond test following RILEM recommendations for monotonic assessment of bond properties, which require a two-point loading (four-point bending) setup. The main challenge was to design a stable cyclic test setup in order to ensure no additional forces generated in the system during the test. High strength self-compacting concrete (HSSCC) beam specimens were chosen for the test; the beam specimens were designed in such a way that they could withstand load reversals.

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  • Seismic performance of high-strength self-compacting-concrete in reinforced concrete beam column joints

    Ashtiani, M.S.; Dhakal, R.P.; Scott, A. (2012)


    University of Canterbury Library

    Beam-column joints of reinforced concrete building frames play an important role under seismic excitations. These are one of the most congested areas in reinforced concrete framed structures; placement of concrete and proper compaction in such areas are hence substantially challenging. This offers a unique area of application for self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration. Therefore if implementing self-compacting concrete in beam-column joints does not compromise seismic performance of the frame, it can be used instead of conventional concrete. This paper focuses on implementation of high-strength self-compacting concrete in beam-column joints and assessment of its seismic behaviour under reversed cyclic loading. Three interior beam-column subassemblies chosen to vary in concrete type and compressive strength are designed as per the New Zealand Standard NZ3101:2006. The specimens are instrumented to measure the load, displacement/drift, ductility, joint shear deformations, and elongation of the plastic hinge zone. The cracking pattern at different load levels and the mode of failure are also recorded and compared among different specimens.

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  • Choice of in-structure damping model: Do we have an answer?

    Puthanpurayil, A.; Dhakal, R.P.; Carr, A.J. (2012)


    University of Canterbury Library

    Recent researches have shown that the optimal distribution of dampers is sensitive to the choice of the in-structure damping models. Common practice is to use the classical viscous damping model originated by Rayleigh, through his famous „Rayleigh dissipation function‟. The main advantage of this model is that the orthogonality of the modes is preserved; thereby rendering the classical modal analysis for undamped vibration readily applicable to damped vibration as well. In a controlled frame, addition of external dampers makes the damping non-classical and the orthogonality of modes no longer exists. So use of the classical in-structure damping model (Rayleigh model) for controlled frames is not convincing and no justification is provided in the literature for the choice of this damping model. In this paper, the effect of choice of the damping models on the optimal distribution of dampers is investigated. It is observed that the optimal distribution of dampers could change based on the choice of the damping models. The results raise a huge concern regarding the realism of the optimality criterion achieved in terms of response reduction when a particular damping model is assumed with no specific justification.

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  • Building pounding damage observed in the 2011 Christchurch earthquake

    Cole, G.; Dhakal, R.P.; Chouw, N. (2012)

    Conference Contributions - Published
    University of Canterbury Library

    This paper describes the pounding damage sustained by buildings in the February 2011 Christchurch earthquake. Approximately 6% of buildings in Christchurch CBD were observed to have suffered some form of serious pounding damage. Typical and exceptional examples of building pounding damage are presented and discussed. Almost all building pounding damage occurred in unreinforced masonry buildings, highlighting their vulnerability to this phenomenon. Modern buildings were found to be vulnerable to pounding damage where overly stiff and strong ‘flashing’ components were installed in existing building separations. Soil variability is identified as a key aspect that amplifies the relative movement of buildings, and hence increases the likelihood of pounding damage. Building pounding damage is compared to the predicted critical pounding weaknesses that have been identified in previous analytical research.

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  • Structural fire performance of steel portal frame buildings

    Moss, P.J.; Dhakal, R.P.; Bong, M.W.; Buchanan, A.H. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper describes a study into the fire behaviour of steel portal frame buildings at elevated temperatures using the finite element programme SAFIR. The finite element analysis carried out in this report was three dimensional and covered different support conditions at the column bases, the presence of axial restraints provided by the end walls, several different locations and severities of fires within the building, different levels of out-of-plane restraint to the columns and the effect of concrete encasement to the columns. From a large number of analyses, it has been shown that the bases of the steel portal frames at the foundations must be designed and constructed with some level of base fixity to ensure that the structure will deform in an acceptable way during fire, with no outwards collapse of the walls. The analyses also showed that it is not necessary for steel portal frame columns to be fire-protected unless the designer wishes to ensure that the columns and the wall panels remain standing, during and after the fire.

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  • Fire performance of portal frame buildings

    Bong, M.W.; Buchanan, A.H.; Dhakal, R.P.; Moss, P.J. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper describes a study into the fire behaviour of steel portal frame buildings at elevated temperatures using the finite element programme SAFIR. The finite element analysis carried out in this report is three dimensional and covers different support conditions at the column bases, the presence of axial restraints provided by the end walls, several different locations and severities of fires within the building, different levels of out-of-plane restraint to the columns and the effect of concrete encasement to the columns. From a large number of analyses, it is shown that the bases of the steel portal frames at the foundations must be designed and constructed with some level of base fixity to ensure that the structure will deform in an acceptable way during fire, with no outwards collapse of the walls. The analyses also showed that it is not necessary for steel portal frame columns to be fire-protected unless the designer wishes to ensure that the columns and the wall panels remain standing, during and after the fire.

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