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This paper describes a new algorithm to obtain reduced-order models for large networks with delay elements. The proposed algorithm can be used in situations where delay extraction-based modeling approaches have been used to model portions of interconnects with low losses, while other portions could be modeled with large networks of lumped components. It is shown that the reduced-order model is passive by construction.

This paper describes a new algorithm for the analysis of high-speed interconnects characterized by frequency-dependent per-unit-length parameter matrices. The proposed technique is based on using the idea of integrated congruence transform to construct a reduced-order system for the interconnect. The reduced-order system offers simple time-domain ordinary differential equations that can be embedded into conventional circuit simulators. The proposed algorithm provides a new approach to perform implicit moment matching on a system described by a mixed set of linear differential algebraic equations. This feature offers a high accuracy in the reduced system over a wide frequency range. The passivity of the reduced-order system is guaranteed. Numerical results demonstrate the validity of the proposed technique

This paper presents a generalized theory of passivity verification in delay-based macromodels for multiconductor transmission line networks generated using the method of characteristics (MoCs). We demonstrate that the passivity in an MoC macro-model is equivalent to the nonnegative definiteness in the admittance matrices of two submodels. We then provide the necessary and sufficient conditions for each submodel to have a nonnegative definite admittance matrix. The presented theory develops an algebraic test to verify the passivity in MoC macromodels. Numerical results demonstrate the validity of the proposed theory.

Blasting is often used in construction, quarrying and mining to fracture rock and remove overburden. While blasting is an efficient method for carrying out these tasks, there are often severe restr...

Over the last few years, several failures in transmission and distribution water/gas pipelines have been reported around the world. The failure of buried pipeline is controlled by several factors, such as pipe material, soil corrosion, internal and external loading, etc. Among these, soil corrosion makes a significant contribution towards failure mode and mechanisms in buried pipes, yet few studies have been done. Although a number of corrosion models have been developed over the years, the applicability of the model predominantly depends on the type of soil and its moisture change over time at the pipe depth. By incorporating a corrosion model, the remaining life of the pipe can be estimated on the basis of applied traffic and pressure loads, which determine the stresses in the pipe segment. Depending on the model, the estimation can show significant variability, and consequently affect the pipe renewal and rehabilitation plans that ultimately have economic impacts. Therefore, it is important for the pipeline asset owners to understand the effect of corrosion models in the remaining life calculation. This paper reviews briefly the available corrosion models and the sensitivity of each parameter in pipe corrosion pit properties and in the remaining life estimation. Finally, a comparison among the corrosion models on the basis of the remaining life estimation is provided to improve the renewal plan.

Timber poles are extensively used in Australia to support overhead electric and telecommunication facilities. The strength of the pole degrades over time, and pole failure can have serious safety and economic implications. The failure occurs when stresses exceed the remaining strength of the timber element. In this paper, a probabilistic framework is developed to estimate the remaining life of the timber power pole system. The developed framework permits the user to consider the variability in the capacity of the timber pole and cross-arm, loading and deterioration processes, and to propagate the uncertainty associated in each stage of the assessment procedure. Further, the time-dependent failure rate of the pole system is estimated to develop the risk matrix to improve the current renewal and replacement decision making process used by the utility companies in Australia.

This paper describes a new approach to the statistical characterization of high-speed interconnect circuits. The proposed approach is based on the idea of polynomial chaos and works by decoupling the matrices that arise from the Galerkin projection. The new approach is general in the sense that it can handle any polynomial system used in the generalized polynomial chaos(gPC) framework.

This paper presents a new approach to statistically characterize the variability of intermodulation distortion of nonlinear RF circuits in response to uncertainty in the design parameters. The proposed approach is built upon two ideas. The first idea is a moment-based computation of the Volterra Kernels. The second idea is derived from the recently reported decoupled formulation of the Hermite-based Polynomial Chaos. The proposed approach enables computing statistical information on the IIP3 at a much lower CPU cost than the traditional MC approach and with comparable accuracy.

The displacement-based modelling methodology which has been applied extensively to buildings and bridges is extended herein to model the over-turning behaviour of rigid free-standing objects. The a...

This paper presents a new algorithm for computing the sensitivity of steady-state responses of nonlinear circuits with respect to an arbitrary network parameter. The proposed algorithm is based on circuit-reduction techniques obtained through nonlinear-projection approaches. The main idea in the proposed sensitivity-computation algorithm is based on projecting the adjoint system of equations onto a subspace of smaller dimension. Continuation methods are then applied on the reduced system to trace the solution trajectory of the adjoint system in the reduced space. We show that once the steady-state solution has been obtained using nonlinear order reduction, the computational cost required to compute sensitivity is only a limited number of forward/backward substitutions. Numerical examples are presented to demonstrate the accuracy and efficiency of the proposed algorithm.

This paper describes a new algorithm for obtaining time-domain sensitivity information of large linear networks via projection-based model-order reduction (MOR) techniques. The proposed algorithm enables adjoint-based time-domain sensitivity analysis techniques to be applied to a large network containing multiple linear multiport subnetworks. In addition, the proposed algorithm can also be used to obtain frequency-domain sensitivity information. The efficiency and accuracy of the proposed work is demonstrated through optimizing the time-domain waveforms of a high-speed interconnect circuit with nonlinear terminations.

This paper presents a new theory that addresses the issue of passivity in macromodels of electrical interconnects constructed based on the method of characteristics (MoC). The proposed approach develops a new algebraic test to check for passivity in macromodels generated using MoC. The theory behind the developed test is based on deriving the necessary and sufficient conditions for the loss of positive-realness in the admittance matrix of the developed macromodel. An algorithmic procedure is proposed to verify passivity of general macromodels derived from the MoC. The results presented in this paper can be employed to test for positive-realness in dynamical systems described by algebraic delay-differential equations with discrete commensurate delays.

Blasting is common in the coal industry to remove rock overburden so that the exposed coal can be mechanically excavated. The ground vibrations and air blast produced by blasting are often felt by residents surrounding the mines. There has been a trend for regulatory authorities, especially those concerned with the environment, to impose low limits on blast vibration levels in response to community pressure, based on human perception and response to vibration. This paper reports the findings of an extensive study on a house which was located adjacent to a coal mine. The house was monitored for over 1 year and was subjected to ground peak particle velocity (PPV) ranging from 1.5 to 222 mm/s. The house was instrumented with accelerometers to measure its dynamic response due to blasting and it was also monitored for cracks before and after each blast. Based on this study, ground motion amplifications along the height of the structure have been established. A simplified methodology presented in this paper has been used to estimate the ground PPV at which cracking is likely.

This paper presents a new approach to predict the racking load-displacement response of plasterboard clad walls found in Australian light-framed residential structures under monotonic racking load. The method is based on a closed-form mathematical model, described herein as the `Modularised` Closed-Form Mathematical model or MCFM model. The model considers the non-linear behaviour of the connections between the plasterboard cladding and frame. Furthermore, the model is flexible as it enables incorporation of different nailing patterns for the cladding. Another feature of this model is that the shape of stud deformation is not assumed to be a specific function, but it is computed based on the strain energy approach to take account of the actual load deformation characteristics of particular walls. Verification of the model against the results obtained from a detailed Finite Element (FE) model is also reported. Very good agreement between the closed form solution and that of the FE model was achieved.

This paper presents a new algorithm that addresses an important issue arising in computation of sensitivity for nonuniform transmission lines using the idea of model reduction through integrated congruence transform. This issue is related extending the concept of implicit basis construction, which was introduced earlier to simulate nonuniform transmission lines, to the task of sensitivity analysis. A new algorithm is presented to compute the orthogonal basis needed to obtain the reduced system used in sensitivity analysis. The proposed algorithm incorporates a new orthogonalization procedure which can be used to find an orthogonal basis for a set of moments derived from inhomogeneous differential equations, but without having to compute those moments explicitly. Numerical results demonstrate that reduced-order systems constructed by the proposed algorithm have improved numerical accuracy in sensitivity computation.

This paper presents a new algorithm for computing sensitivity information of nonuniform multiconductor transmission lines with respect to arbitrary physical parameters. The proposed algorithm provides sensitivity information through a reduced-order system that has a simple representation in the time-domain. This feature enables computing sensitivity in the presence of nonlinear terminations. The proposed algorithm is based on the concept of passive model-order reduction using integrated congruence transform. It also addresses the problem of sensitivity analysis for nonuniform multiconductor transmission lines without having to resort to any discretization techniques

This paper presents a new algorithm based on integrated congruence transform for efficient simulation of nonuniform transmission lines. The proposed algorithm introduces the concept of model-order reduction (MOR) via implicit usage of the Hilbert-space moments in distributed networks. The key idea in the proposed algorithm is the development of an orthogonalization procedure that does not require the explicit computation of the Hilbert-space moments in order to find their spanning orthogonal basis. The proposed orthogonalization procedure can thus be used to compute an orthogonal basis for any set of elements that are related through a differential operator in a generalized Hilbert space, without the need to have these elements in an explicit form. The proposed algorithm also addresses the problem of MOR of nonuniform transmission lines, through defining a weighted inner product and norm mappings over the Hilbert space of the moments. Numerical examples demonstrate more accurate numerical approximation capabilities over using the moments explicitly.

This paper introduces the use of elastic displacement floor spectra to model the seismic performance behavior of unrestrained components. The displacement spectrum has the attribute of tracking period-shifts associated with "rocking" behavior. Analyses of the displacement floor spectra in high-rise buildings demonstrate the significance of contributions by the higher modes of vibration. Significantly, such higher mode contributions could not always be captured by established code procedures wherein the seismic demand on a building floor is obtained by linear interpolation between the seismic demand at the roof and ground level. The significant influence of the higher modes in high-rise buildings also precludes the use of simple static models to predict seismic demand. Results are also presented herein to demonstrate the sensitivity of the displacement floor spectrum to a multitude of modeling uncertainties.

The Australian Residential Timber-Framed Construction standard (AS1684:1999) has recently been revised to explicitly define the bracing contribution of nominally fixed plasterboard clad walls as 0.45 kN/m for cladding on one side and 0.75 kN/m for cladding on two sides. These values clarify the allowance, which designers may rely upon for the presence of plasterboard and their inclusion in the standard infers a necessity for plasterboard products to at least meet these requirements. A review of the relevant Australian, ISO, and ASTM standards, as well as plasterboard manufacturers' in-house quality control tests has established that these tests mainly focus on serviceability aspect of plasterboard (e.g., storage, transportation, and installation) rather than that of structural bracing performance. It has also been determined that there are no direct correlations between serviceability conditions and structural bracing performance of plasterboard. In fact, a limited set of data provided by the plasterboard manufacturers shows that almost no correlation exists between the current quality control tests and the most commonly measured parameter, the density of plasterboard. It has been concluded that current tests are inadequate to serve as control measures for bracing performance of plasterboard. Nonetheless, it must be noted that density is not the only parameter that may influence the bracing performance of plasterboard; other parameters such as linerboard strength and bonding between gypsum and linerboard may also affect the bracing capacity. This paper details a new test, termed fastener bearing test, which provides a method to evaluate the bracing capacity of plasterboard. The results of this test show a very high correlation with shear connection tests. The proposed test is practical and simple to perform as part of the manufacturing process, in addition to the current tests, without severe cost and time penalty to the plasterboard manufacturers.

Although Egypt's relations with Europe have always fluctuated between conflict and cooperation, the policy consensus in Egypt today is that relations with Europe are vitally important and that any ...

This paper proposes a new method to limit vibrations from blasting to avoid damage to residential structures. The evolution of commonly adopted vibration limits and standards adopted for surface blasting operations in close proximity to residential areas is reviewed. The importance of human sensitivity to vibrations is highlighted and vibration limits preventing damage are demonstrated to be influenced by human annoyance. A robust and rational procedure is presented to replace existing vibration standards limiting vibration using the acceleration- displacement response spectrum methodology commonly adopted in earthquake engineering. The proposed approach adopts drift as a measure of damage rather than the current industry accepted measurement of ground velocity.

While the design and technology of conventional low rise light framed residential structures are relatively simple, their response to lateral loading is quite complex. This is due to the high degree of redundancy, the irregular geometry and interaction between the structural and non-structural components. In addition, the designated lateral bracing elements within one structure may exhibit significantly different behaviour due to the different bracing actions and different materials. This paper focuses on the bracing capacity of plasterboard clad walls which could be considered either structural or non-structural. While such walls may be installed purely as partition walls, they may provide lateral strength and stiffness due to the complex load paths. The paper presents in detail the possible load transfer mechanisms to a variety of typical walls. It also highlights the difficulty with performing racking tests on isolated walls due to the complex boundary conditions surrounding walls in real structures. In addition, the paper reports racking test results that demonstrate the effects of different boundary conditions on the load carrying capacity and the failure modes.

Transient analysis of Switching Power Converter (SPC) circuits is a computationally expensive task. This high expense arises from the fact that these circuits are driven by a clock with a period that is very small compared to the time interval the designer is typically interested in. Envelope-Following (EF) technique has been recently proposed in the literature for efficient time-domain simulation of SPC circuits. In this paper, a parallel high-order EF method, which is based on Obreshkov-Formula, is presented for analysis of SPC circuits. A numerical example is presented to demonstrate the efficiency and scalability of the proposed method on parallel platforms.

A novel Envelope Following (EF) method is presented for fast and accurate transient simulation of microwave and RF circuits with almost-periodic responses. Targeted circuits contain high-frequency components whose amplitudes vary slowly. The proposed high-order EF method is based on a stable and high-order Obreshkov formula (ObF). Use of high-order formula allows accurate and fast analysis while keeping the same accuracy as the conventional low-order integration methods and is validated by the presented numerical example.

This paper presents a new approach to statistically characterize the variability of the steady-state analysis which results due to uncertainty in the design parameters. The new approach is based on the concept of Polynomial Chaos (PC). However, unlike the traditional PC, the proposed approach adopts a new mathematical formulation that decouples the PC problem into several problems with smaller size that can be analyzed much more efficiently.

This paper presents a new approach aimed at limiting the growth of the computational cost of variability analysis, of nonlinear circuits, using the Hermite-based Polynomial Chaos (PC), with the increase in the number of random variables. The proposed technique is based on deriving a closed-form formula for the structure of the augmented Jacobian matrix generated by the PC approach, and then shows that this structure can be approximated with a different structure that can be decoupled into independent diagonal blocks.

The point fixed glass facade system (PFGFS), also known as a spider glass system, is popular because it is the most transparent facade system available for buildings. The glass facade system is fixed to the support structure at minimal points using bolts and spider arms. Generally, the racking performance of these systems is not considered at the design stage. The facade system will be vulnerable to racking actions mainly during severe earthquakes and wind actions if the system does not have sufficient in-plane drift capacity. A unique real-scale in-plane racking laboratory test on a typical PFGFS was conducted to assess the in-plane racking performance. A maximum drift of 2.1% was measured, which was much larger than initially anticipated because of the rigid-body articulation of the system and higher than typical maximum allowable interstory drift for buildings in regions of lower seismicity. A sophisticated nonlinear finite-element (FE) model was developed and conservatively benchmarked against...

There has been a significant worldwide increase in the use of cold-formed steel in low-rise resi dential structures as an alternative to timber. A major research project to assess the performance under lateral loading of cold-formed steel frames commenced more than 7 years ago at The University of Melbourne, Australia, in collaboration with industry and other research organizations. This paper reports key findings from an extensive experimental program. It details a particular aspect of the program that uses nondestruc tive dynamic testing to identify the basic dynamic properties of such structures. Laboratory tests, employing a shaking table, have been conducted on unclad wall panels and a model test house to study the influence of different framing connection types and to assess the influence of nonstructural components, namely, plas terboard interior lining and brick-veneer exterior cladding. The findings from these tests were verified and further extended by testing a full-scale prototype house at various stages of construction. This paper presents information concerning typical natural frequencies and mode shapes for such structures. It also details the contribution of nonstructural components to the lateral stiffness, which was found to be significant. The re sults have important implications for seismic design and performance of such structures, even in regions of low to moderate seismicity.

Signal integrity analysis has become imperative for high-speed designs. In this paper, we present a new technique to advance Krylov-space-based passive model-reduction algorithms to include distributed interconnects described by telegrapher's equations. Interconnects can be lossy, coupled, and can include frequency-dependent parameters. In the proposed scheme, transmission-line subnetworks are treated with closed-form stamps obtained using matrix-exponential Pade, where the coefficients describing the model are computed a priori and analytically. In addition, a technique is given to guarantee that the contribution of these stamps to the modified nodal analysis formulation leads to a passive macromodel.

Computing the steady-state response of large nonlinear circuits is becoming a key simulation requirement due to the rapid market growth of RF silicon integrated circuits. In this paper, we describe a nonlinear circuit reduction algorithm for finding the steady-state response. The proposed algorithm uses a congruent transformation-based technique to reduce the harmonic-balance equations into a much smaller set of equations. The main feature of the reduced circuit is that it shares with the original one a certain number of the derivatives with respect to the RF input power, steady-state analysis is then carried out on the reduced circuit instead of the original circuit.

This paper reviews aspects of current design procedures for seismic design of structures, and specifically examines their relevance to the design of light framed residential buildings under earthquake loading. The significance of the various structural contributions made by the components of cold formed steel framed residential structures subjected to earthquake induced loadings has been investigated. This is a common form of residential construction worldwide. Particular attention is given to aspects related to ductility and overstrength, the latter arising principally from the contributions of the designated "non-structural" components. Based on both analytical and experimental data obtained from research investigations on steel framed residential structures, typical ranges of the ductility reduction factor and overstrength ratios are determined. It is concluded that the latter parameter has a very significant influence on the seismic design of such structures. Although the numerical ranges for the inelastic seismic parameters given in this paper were obtained for Australian houses, the concepts and the highlighted aspects of seismic design methodology are more widely applicable.

This letter introduces a new approach to obtain passive delay-based macromodels for lossy multiconductor transmission lines. The proposed approach uses the notion of symplectic integrators to obtain fourth-order passive approximations to the exponential matrix with delay extraction. This approach can therefore be considered a generalization to previous delay-extraction-based techniques which adopt second-order approximations to the exponential function.

This paper presents key outcomes of an investigation in the performance of domestic structures with cold formed steel frames. The primary objective of this research project was to assess the performance and behaviour of these structures when subjected to earthquake loading. The research involved an extensive racking and dynamic testing program on both two- and three-dimensional framing configurations. A variety of construction details was tested to identify the critical components and assess the contributions from the non-structural components, particularly the plasterboard lining. It is concluded that the steel frames perform very well under earthquake loads. Non-structural components, such as plasterboard lining, make a significant contribution to the lateral bracing of the frames. The failure mechanisms and the load sharing between the various components are also identified and discussed.

This paper presents a detailed investigation into the contribution of plasterboard to the lateral resistance of cold-formed steel-framed residential structures. It details the development of a finite-element model for laterally loaded plasterboard-lined cold-formed steel wall frames for residential construction. The model utilizes nonlinear element properties and three-dimensional geometrical configurations and is capable of simulating the influence of boundary conditions such as corner return walls and ceiling cornices. The analytical results from the finite-element model were successfully verified against experimental racking test results. A sensitivity analysis was conducted using the model to study the influence of return walls, ceiling cornices, and wall length on the lateral capacity of the wall system. It is concluded that a wall with corner return walls, ceilings cornices, and skirting boards has more than three times the lateral capacity of an identical isolated wall panel. The relationship between the wall length and the ultimate lateral load-carrying capacity of the wall system is dependent on the presence of these boundary conditions.

We propose a new wavelet method for steady-state analysis of nonlinear circuits. The new method inherits the robustness of wavelet-based technique in handling very strong nonlinear circuits while offering significant reduction of simulation costs for circuits with widely separated time scales

Long-span lightweight floor systems with low damping are susceptible to serviceability problems due to human excitations. This paper discusses two remedial measures to alleviate disturbing footfall-induced vibrations observed on a real office floor of steel-concrete composite construction. One treatment involves stiffening the existing floor beams while the other utilises passive control with an innovative distributed multiple viscoelastic tuned mass damper (TMD) system. Several finite element models reflecting different remedial scenarios are analysed from which the TMD approach and the traditional stiffening technique are found to be comparably effective in reducing the vibration level. However, the proposed TMD solution is far superior, feasible and non-intrusive when applied to existing floors. A probability-based evaluation of the effectiveness of the TMD system is also conducted, taking into account likely variations in the walking force and dynamic properties of both the floor and dampers. The custom-made damper system has been successfully installed on the real floor and performed efficiently in various field tests.

This paper presents the findings of a research project investigating the lateral load drift behaviour of lightly reinforced concrete columns. Such columns of limited ductility are common in regions of low-moderate seismicity, and although their strength properties are well defined, the drift performance is less understood. The paper presents the results of an experimental study undertaken and the development of a theoretical model for predicting the lateral load-drift behaviour of lightly reinforced concrete columns together with a simplified bi-linear model for checking purposes. The test results are presented and clearly indicate the dramatic impact that the axial load ratio has on the drift performance of columns of limited ductility, particularly the significantly lower drift capacities that are available in compression dominated columns.

This work discusses the stability issues of PI-based brushless DC motor (BLDCM) speed controllers under the presence of strong time delay in the controller loop. Understanding of the time delay effect is of paramount importance to increase performance, quality and productivity in important modern applications. Unfortunately, the time delay effect in the speed controller asymptotic stability has not been well studied in the existing literature. In this work, we present an algebraic technique to calculate the maximum time delay that can be accepted in the control loop of a BLDCM speed controller before the response becomes unstable. Initially, we derive an analytical model for the set point tracking (SPT) and the load disturbance rejection (LDR) responses taking into account the various sources of time delay. Using a recently proposed stability analysis methodology, we derive accurate stability conditions for the BLDCM speed controller. The results show that tuning the PI controller for very fast response causes the time delay to significantly affect the system stability. As an example, the asymptotic stability of the LDR of a sensored controller is analyzed. The method proposed here can be easily extended to analyze the stability of the SPT response and the stability of sensorless controllers such as the direct Back EMF.

In areas of low to moderate seismicity many building contents and equipment are not positively fixed to the floor or tied to adjacent walls. Under seismic induced horizontal vibration, such contents and equipment can suffer from damage by either overturning or impact associated with rocking. This paper focuses on the estimation of shock on typical contents and equipment due to rocking. A simplified analytical model is outlined that can be used to estimate the maximum acceleration on a rocking object given its basic geometric and mechanical properties. The developed model was validated against experimental results. The experimental results revealed that the maximum shock acceleration can be underestimated if the static stiffness of the materials at the interface between the rocking object and floor is used rather than the dynamic stiffness. Excellent agreement between the model and experimental results was found when the dynamic stiffness for the interface material was used, which was found to be generally much higher than corresponding static stiffness under different investigated boundary conditions of the cushion. The proposed model can be a beneficial tool in performing a rapid assessment of shock sensitive components considered for possible seismic rectification., {"references":["","FEMA 356,Prestandard and Commentary for Seismic Rehabilitation of\nBuildings. Prepared by the American Society of Civil Engineers for the\nFederal Emergency Management Agency. FEMA, 2000.","IBC, International Code Council. International building Code, U.S.A.,\n2000.","AS/NZS 1170.4, Australian Standard for Structural Design Actions,\nPart 4: Earthquake Actions in Australia. 2005.","G.W.Housner, \"The Behaviour of inverted pendulum\nstructures,\"Bulletin of the Seismological Society of America, 53 (2), 403-\n417. 1963.","S.C.S.Yim, A.K.Chopra, and J.Penzien, \"Rocking Response of Rigid\nBlocks to Earthquakes,\" Earthquake Engineering and Structural\nDynamics 122(7), 69093. 1980.","M.Aslam, W.G.Godden, and D.T.Scalise, \"Earthquake rocking response\nof rigid bodies,\" Journal of the Structural Division, 106, 377-392, 1980.","Y.Ishiyama, \"Motions of rigid bodies and criteria for overturning by\nearthquake excitations,\"Earthquake Engineering and Structural\nDynamics, 10, pp. 635-650. 1982.","S.J.Hogan,\"On the dynamics of rigid-block motion under harmonic\nmotion,\" Proc. R. Soc. Lond, 425, 441-476. 1989.","P. R. Lipscombe, Dynamics of rigid block structures. Ph.D. thesis,\nUniversity of Cambridge, 1990.\n[10] N. Makris and Y.Roussos, \"Rocking Response and Overturning of\nEquipment Under Horizontal Pulse-Type Motions,\" Pacific Earthquake\nEngineering Research Center PEER 1998, Report No. 5, 1998.\n[11] N.Makris and D.Konstantinidis, \"The Rocking Spectrum and the\nShortcomings of Design Guidelines,\" Pacific Earthquake Engineering\nResearch Center PEER 2001, Report No. 7, 2001.\n[12] H.Al Abadi, Unrestrained Building Contents in Regions of Low-\nModerate Seismicity. Ph.D. thesis, Civil Engineering Dept., The\nUniversity of Melbourne, Melbourne, 2008.\n[13] H. Al Abadi, N.Lam, and E.Gad, \"A simple displacement-based model\nfor predicting seismically induced overturning,\" Journal of Earthquake\nEngineering, 2006 10(6), 775–814, 2006.\n[14] H.Al Abadi, N.T.K.Lam, E.F.Gad, and A.M.Chandler, \"Earthquake\nFloor Spectra for Unrestrained Building Components,\" International\nJournal of Structural Stability and Dynamics, 4 (3), 361-377, 2004.\n[15] D.Franke, N.Lam, E.Gad, and A.Chandler, \"Seismically Induced\nOverturning of Objects and Filtering Effects of Buildings,\" International\nJournal of Seismology and Earthquake Engineering, 7 (2), 95-108,\n2005.\n[16] B.Kafle, N.Lam, E.Gad, and J.Wilson, \"Displacement controlled rocking\nbehaviour of rigid objects,\" Earthquake Engineering and Structural\nDynamics, 40, 1653-1669, 2011.\n[17] N.Lam, M.Griffith, J. Wilson, and K. Doherty, \"Time History Analysis\nof URM walls in out-of-plane flexure,\" Journal of Engineering\nStructures, 25 (6), 743-754, 2003.\n[18] M.C.Griffith, N.T.K. Lam, J.L. Wilson, and K.Doherty, \"Experimental\nInvestigation of Unreinforced Brick Masonry Walls in Flexure,\" Journal\nof Structural Engineering, 130(3), 423-432, 2004.\n[19] K.Doherty, M.Griffith, N.T.K. Lam, and J.L.Wilson, \"Displacement-\nBased Analysis for out-of plan bending of seismically loaded\nunreinforced masonry walls,\" Earthquake Engineering and Structural\nDynamics, 31(4), 833-850, 2002.\n[20] E.Lumantarna, N.T.K. Lam, J.L.Wilson, and M.C.Griffith, \"Inelastic\nDisplacement Demand of Strength Degraded Structures,\"Journal of\nEarthquake Engineering, 14: 487-511, 2010.\n[21] N.T.K.Lam and E.G.Gad, \"Overturning of Non-structural Components\nin Low-moderate Seismicity Regions. Special Issue on Earthquake\nEngineering in Low-Moderate Seismicity Regions of Southeast Asia and\nAustralia,\" Electronic Journal of Structural Engineering, 121-132. 2008.\n[22] S.Goyal, E. K. Buratynski, and G. W. Elko,\"Role of Shock Response\nSpectrum in ElectronicProduct Suspension Design,\" The International\nJournal of Microcircuits and Electronic Packaging, vol. 23, no. 2, pp.\n182-190, Second Quarter2000.\n[23] H.Al Abadi, N.Lam, E.Gad, and J. Petrolito, \"A Simple Model for\nEstimating Shocks in Unrestrained Building Contents in an Earthquake,\"\nJournal of Earthquake Engineering,in press.\n[24] M.Avalle, G. Belingardi, and R. Montanini,\"Characterization of\npolymeric structural foams under compressive impact loading by means\nof energy-absorption diagram,\"International Journal of Impact\nEngineering, 25, 455-472, 2001.\n[25] R.R.A.Cousins, \"Theory of the Impact Behaviour of Rate-Dependent\nPadding Materials,\"Journal of Applied Polymer Science, 20, 2893-2903,\n1976.\n[26] O.Ramon and J.Miltz, \"Prediction of Dynamic Properties of Plastic\nFoams from Constant-Strain Rate Measurements,\" Journal of Applied\nPolymer Science, 40, 1683-1692, 1990.\n[27] R.W.Shuttleworth, V.O.Shestopal, and P.C.Goss, \"Open-Cell Flexible\nPolyurethane Foams: Comparison of Static and Dynamic Compression\nProperties,\" Journal of Applied Polymer Science, 30, 333-343, 1985."]}

Spring-connected lumped mass models are well-known tools for simulating the impact actions including forces generated at the point of contact which are responsible for localized damage to the target. However, the stiffness properties of the impactor would need to be known in order that such contact forces can be simulated with good accuracies. For most projectile materials, such information required for modeling is not available. A computational algorithm which forms part of a new modeling technique for simulating the contact forces is introduced in this paper. Cricket ball was used as the example impactor to illustrate the procedure.

This paper presents a new method for a circuit-based transient simulation of large interconnects circuits terminated with nonlinear devices. The proposed method is based on high-order A-stable integration methods, known as Obreshkov-formula. The new method exploits the structure of the matrices resulting from applying Obreshkov-formula to achieve very high speedups. A numerical example is presented that shows the performance and accuracy of the proposed method.

Oxidative phenol coupling reactions are required to establish the cross-linked heptapeptide backbone of vancomycin. The first cross-linking reaction, catalyzed by the P450 enzyme OxyB, is dramatically slower when a chlorine substituent is present in the hexapeptide-S-PCP substrate and is abolished when chlorine is introduced into a potential heptapeptide-S-PCP substrate.

This paper describes an efficient technique for simulating large linear circuits in the time-domain using high-order stable methods. The target area of the proposed technique is in circuit-based simulation of the large linear circuits that arise from full-wave modeling of distributed passive structures such as transmission-lines and microstrip elements. In these applications, the cost of linear system solution typically dominates the computational effort at each time-step. The proposed method takes advantage of the special structure of the block matrices in these applications to reduce the computational cost significantly.

This paper describes a multi-core algorithm for the Obreshkov Formula based high-order A-stable and L-stable numerical methods targeting transient simulation of interconnect and highs-speed circuits. The goal of the proposed algorithm is to efficiently simulate those circuits that arise from full-wave modeling of distributed passive structures such as transmission-lines, microstrip elements, and high-speed interconnects circuits. We show that the special mathematical formulation of these circuits enables decoupling of the matrix, whose factorization is required by the high-order method, into several matrices with smaller size that can be factorized in parallel on multi-core architectures efficiently.

This paper describes the structural assessment work carried out by the West Gate Bridge Strengthening Alliance ("WGBSA") on the West Gate main cable-stayed bridge in devising the necessary strengthening measures for stiffened panels whilst minimizing the need to remove red- lead paint. As a consequence of this work, questions have been raised as to the safety of various stiffener buckling clauses in UK assessment code BD 56[1],[2] and BS 5400 Part 3[3]. The authors discuss the answers to these questions that were able to be addressed within the time-frame of the West Gate strengthening project. Additional issues which require future research are documented at the end of the paper.

This paper presents analytical and experimental studies on the application of an innovative viscoelastic tuned mass damper system to mitigate disturbing footfall induced vibrations observed on a real office floor. The damper system consists of a number of steel-rubber sandwich beams arranged in a distributed form. Different tuning scenarios were investigated via FE simulations, demonstrating that dampers appropriately tuned to multi frequencies would be more effective than those tuned to a single frequency. The influence of the installation of the dampers on a floor bay on the response of the adjacent bay is also discussed. The custom-made dampers have been successfully installed on the existing floor without requiring any architectural or structural modifications. Results from numerical investigation and field tests show that the dampers can reduce at least 40% of the floor response to an acceptable level for human comfort in an office environment.

Structures such as unreinforced masonrywalls, soft-storey buildings, gravity structures and nonstructural components which include free-standing objects are well known to be non-ductile and yet commonly found in regions of low-moderate seismicity. Potential significant degradation in strength in these structural systems in projected earthquake scenarios has been a cause for concern. Shaking table experiments undertaken earlier by the authors revealed very interesting phenomena with the behaviour of ("non-ductile") free-standing objects in an earthquake. Importantly, the displacement time histories predicted by non-linear time history analysis are shown to be consistent with recordings from shaking table experiments. Push-over field tests on a soft-storey building in Melbourne demonstrated force-displacement behaviour that is characterized by predominant P-Δ effects (as is observed with free-standing objects). The force-displacement relationship obtained from field-tests has been used for analytical simulations of seismic response. This paper presents results of parametric studies based on non- linear THA of such structures. © 2011 Taylor & Francis Group, London.

This paper presents the results of an experimental study that has investigated the strength and stiffness of a moment-resisting connection between a universal steel beam and a concrete-filled RHS (rectangular hollowsection) column. In this connection double built-up tees are blind-bolted to the rectangular hollowsection. Extensions are provided to the Ajax "One-Side" blind bolts to link the connection back into the concrete within the tube, and hence to enhance the stiffness of the connection. The objective of this study is to develop a novel bolted moment connection that is easy to construct for Australian practice. The structural performance of the blind-bolted connection is evaluated in term of the moment-rotation relationship, failure mode, and the deformation pattern within critical components.A simplified component model is developed to predict the initial stiffness of this blind-bolted moment connection. © 2011 Taylor & Francis Group, London.