Establish Design Criteria Research Articles

The seismic retrofit of UC Berkeley's California Memorial Stadium

SUMMARYThis paper addresses the seismic retrofit of the University of California at Berkeley's California Memorial Stadium (CMS) to accommodate surface fault rupture movements as well as intense seismic shaking from the Hayward fault. For the surface fault rupture aspect of the project, the project team took a multidisciplinary approach that involved structural engineers, geotechnical engineers, seismologists and geologists collaborating to establish design criteria and possible surface rupture scenarios. The mechanics of surface fault rupture are discussed relative to the structural design approach that mitigates the effects of surface deformations caused by the fault during an earthquake. The effects of the surface fault rupture were studied using small scale physical models and nonlinear finite element models of the building and rupturing ground surface. The retrofit scheme accommodates the concentrated ground deformations of an estimated 6 ft of horizontal movement and 2 ft of vertical offset caused by a surface fault rupture. Segments of the CMS that overlay the regions of possible surface fault rupture were decoupled from the main structure via movement gaps to accommodate relative displacements of the building segments, including tilting in the event of earthquake‐produced fault rupture. The results of the analyses are discussed along with the design decisions and challenges of retrofitting a historic structure that resides on an active fault. While a large portion of the engineering effort was devoted to solving the issue of accommodating surface rupture, another large engineering challenge also dominated the design of the CMS. One of the signature architectural features of the stadium is a two‐story, 375‐ft long press box that hovers above the new west side of the seating bowl. Although designing the press box on limited supports to give the appearance of ‘hovering’ was a challenge, the real challenge came in safely bracing this structure for large potential ground motions at this site. The interface between the flexible support of the press box and the rigid seating bowl became a challenge, solved by providing a separation between the bowl and press box structures allowing them to move independently while linking them only with fluid viscous dampers. Copyright © 2012 John Wiley & Sons, Ltd.

Performance-based seismic analysis and design of code-exceeding tall buildings in Mainland China

Design codes provide the minimum requirements for the design of code-compliant structures to ensure the safety of the life and property. As for code-exceeding buildings, the requirements for design are not sufficient and the approval of such structures is vague. In mainland China in recent years, a large number of code-exceeding tall buildings, whether their heights exceed the limit for the respective structure type or the extent of irregularity is violated, have been constructed. Performance-based seismic design (PBSD) approach has been highly recommended and become necessary to demonstrate the performance of code-exceeding tall buildings at least equivalent to code intent of safety. This paper proposes the general methodologies of performance-based seismic analysis and design of code-exceeding tall buildings in Mainland China. The PBSD approach proposed here includes selection of performance objectives, determination of design philosophy, establishment of design criteria for structural components and systems consistent with the desirable and transparent performance objectives, and seismic performance analysis and evaluation through extensive numerical analysis or further experimental study if necessary. The seismic analysis and design of 101-story Shanghai World Financial Center Tower is introduced as a typical engineering example where the PBSD approach is followed. The example demonstrates that the PBSD approach is an appropriate way to control efficiently the seismic damage on the structure and ensure the predictable and safe performance.

Foundation connections for circular concrete-filled tubes

Concrete filled steel tubes (CFTs) promote economical and rapid construction. They offer increased strength and stiffness relative to structural steel and reinforced concrete. The steel tube serves as formwork and reinforcement to the concrete fill, thereby reducing the labor requirements. CFT components encourage the optimal behavior of each material (concrete and steel) while providing a symbiotic relationship between the two to mitigate undesirable failure modes. The fill increases the compressive strength and stiffness, delays and restrains local buckling of the tube, and enhances ductility and resistance if composite action is achieved.Both rectangular and circular CFT have been employed, but circular CFT provide better performance, because they provide increased confinement of the concrete and composite action. A missing component for circular CFT construction is reliable and ductile connections. The research described herein that investigated and develops design procedures for simple and economical connections of circular CFT piers or columns to reinforced concrete foundations, pile caps and wide cap beams (bridge construction) is presented and evaluated. The connection requires no dowels or internal reinforcement connecting the tube to the footing or cap beam. Experiments and analytical studies evaluate the inelastic seismic performance and establish design criteria for the connection. The seismic performance of a CFT column and connection assembly is compared to a conventional reinforced concrete column. The research shows that the proposed connection develops the full capacity of the composite column. The assembly provides excellent ductility and inelastic deformation capacity under seismic loading while mitigating damage even at larger drift demands.

Partial coherence theory for x-ray phase contrast imaging technique with gratings

The partial coherence theory is applied to study the x-ray Talbot-Lau interferometry for phase contrast imaging with extended and polychromatic sources. Under a geometric condition for grating periods and distances between gratings, moiré fringes at the analyzer grating can be the same as the case of using one single slit. Although this geometric condition has been proposed before, we provide a quantitative explanation of the geometric condition compared to previous heuristic understanding. We then investigate the fringe visibility at the analyzer grating. For quasi-monochromatic sources, we derive an analytical formula and demonstrate that the visibility can reach 100% if the duty cycle of the source grating is less than an explicitly given bound. For polychromatic sources, we conduct numerical simulations to show that the visibility could reach near 100%. Both 1D- and 2D-grating systems are studied in this manuscript, respectively. Further work is to evaluate the theoretical results with physical experiments and establish design criteria for Talbot-Lau interferometers.

Stochastic Assessment of Reservoir Storage-Yield Relationships in Portugal

AbstractThis paper aims to establish design criteria that simultaneously meet (1) the stochastic nature of the streamflow regime in Portuguese rivers and (2) the relationship between such a regime and the mean annual flow depth. The data set consists of 54 streamflow samples from unregulated Portuguese rivers. A large number of synthetic streamflow series were generated by using a probabilistic model at the annual level and a disaggregation model, namely the method of fragments, at the monthly level. Based on an operation with fixed yield and time-based reliability, behavioral analysis was applied to the synthetic series to estimate the storage capacities of hypothetical reservoirs. The Gumbel distribution was fitted to the previous estimates to obtain design storage capacities with specified values of reliability. After showing that the former design capacities were significantly correlated with the mean annual flow depth of the sample series, curves that expressed that relationship were defined. The res...

Kinetics of nitrate removal in wetlands receiving agricultural drainage

The kinetics of nitrate removal in wetlands receiving agricultural drainage from irrigated cropland was investigated with the objective of establishing design criteria for incorporation of ecosystem services in agricultural watersheds. Existing wetlands receiving drainage from irrigated agriculture demonstrated nitrate mass removal efficiencies between 23% and 35%. Areal nitrate removal rates (J) ranged from 142 to 350mg-Nm−2d−1. Modified areal first-order rate constants for field sites varied between 4.00 and 12.07cmd−1. Saturation kinetics (Monod or Michaelis–Menten type kinetics) was determined in a supplemental microcosm study using sediments from one wetland by manipulating the loading rate. The apparent half-saturation constant (Km) and maximum removal rate (Jmax) were 43.8mgL−1 and 4.11gm−2d−1 for these sediments. The first-order rate constant from the microcosm (12.97cmd−1) was statistically the same as to the value for the field site. The results suggest that supplementing field studies with a well-controlled laboratory microcosm study was useful for confirming kinetic parameters derived from field data. It was determined that less than 3% of the land in these agricultural watersheds would need to be managed as wetland to reduce the drainage nitrate concentration to below 0.5mgL−1.

Geometric Design, Speed, and Safety

A performance-based approach to the interaction of geometric design, speed, and safety is considered given the availability of two key documents: the Highway Safety Manual and Modeling Operating Speed: Synthesis Report. A historical look at the concept of design speed shows that although the definition of design speed has changed on more than one occasion, the same basic philosophy that related design speed to a safe speed is still reflected in current policy in supplemental guidance related to the selection of design speed. A conservative approach to establishing design criteria, used to address the range of driver, vehicle, and roadway conditions and capabilities that a designer must consider, is demonstrated. Operating speeds are shown to be higher than design speeds for design speeds of approximately 55 mph or less. This outcome may be considered undesirable, but that categorization seems to be based more on subjective judgments of what is desirable than on actual safety findings. Finally, the idea of speed management through the use of roadway geometrics (i.e., geometric designs that influence driver selection of operating speed)—one component of self-enforcing, self-explaining roadway design—is explored. Findings uncover possible challenges to implementing this idea. Five related questions are addressed: (a) What is known about the relationships between road geometry and operating speeds? (b) To what degree does road geometry influence operating speeds? (c) How are safety and security influenced by road geometry? (d) What are the potential impacts on large vehicles? and (e) What is the nature of the speed–safety trade-off?

Analysis and design of different control strategies of hybrid active power filter based on the state model

A configuration consisting of a combination of a series active power filter (APF) and a parallel passive filter is shown to be an efficient system for non-linear load compensation. For this topology, different compensation strategies are proposed to control the series APF. The most effective strategies determine the APF compensation voltage in proportion to the source current harmonics. The proportionality constant ` k ' in the control algorithm implementation is related to the APF gain and complete system dynamic. In this study, the system state model is obtained for three control strategies of series APF: compensation voltage proportional to source current harmonics, compensation voltage opposite to the load voltage harmonics and a hybrid strategy which combines both previous strategies. The analyses of the resulting models provide the information needed to establish design criteria with respect to harmonic filtering and system stability. The methodology proposed in this study eliminates the arbitrary choice of the proportionality constant. The three strategies were analysed in two different situations: sinusoidal supply voltages and distorted supply voltages. Finally, results of an experimental prototype developed for this purpose allowed the proposed analysis to be verified.

Composite Catalytic-Permselective Membranes: A Strategy for Enhancing Selectivity and Permeation Rates via Reaction and Diffusion

This manuscript presents a new strategy for enhancing permselective films via the addition of a porous, catalytically active layer in a composite catalytic-permselective membrane design. A general mathematical analysis of reaction and diffusion within the catalytic layer is presented in order to establish design criteria. Numerical simulations are presented for the case of the water-gas-shift reaction supporting hydrogen purification, to demonstrate the advantages of the composite catalytic-permselective design concept. For the case of a water-gas-shift catalytic coating placed atop a hydrogen-permselective dense palladium film, an 84% reduction in carbon monoxide (CO) exposure is predicted, along with a mild (8%) increase in the overall hydrogen permeation rate; this reduction in carbon monoxide contamination of the palladium surface represents a significant improvement in palladium film utilization. For the case of the same catalytic coating placed atop a carbon dioxide (CO2)-permselective polymer film, CO2–CO permselectivities are increased by two orders of magnitude.

Hybrid active power filter: design criteria

The configuration of a series active power filter (APF) and a parallel passive filter (PPF) has proven to be an efficient system for nonlinear load compensation. For this topology, different compensation strategies have been proposed to control the series APF. The most effective strategy determines the APF refrerence voltage as a proportion of the source current harmonics. The proportionality constant in the control algorithm implementation is related to the APF gain and the system dynamics. In this paper, the system state model has been obtained for three control strategies of series APF: voltage proportional to source current harmonics, voltage opposite to the load voltage harmonics and a hybrid strategy which combines both previous. The resulting model analyses provide the information needed to establish design criteria for each strategy, both in terms of harmonic filtering and the system stability. The three strategies were compared in two different situations: sinusoidal supply voltages and distorted supply voltages. Finally, results of an experimental prototype developed for this purpose allowed the proposed analysis to be verified.

Targeting kidney mesangium by nanoparticles of defined size.

Nanoparticles are being investigated for numerous medical applications and are showing potential as an emerging class of carriers for drug delivery. Investigations on how the physicochemical properties (e.g., size, surface charge, shape, and density of targeting ligands) of nanoparticles enable their ability to overcome biological barriers and reach designated cellular destinations in sufficient amounts to elicit biological efficacy are of interest. Despite proven success in nanoparticle accumulation at cellular locations and occurrence of downstream therapeutic effects (e.g., target gene inhibition) in a selected few organs such as tumor and liver, reports on effective delivery of engineered nanoparticles to other organs still remain scarce. Here, we show that nanoparticles of ~75 ± 25-nm diameters target the mesangium of the kidney. These data show the effects of particle diameter on targeting the mesangium of the kidney. Because many diseases originate from this area of the kidney, our findings establish design criteria for constructing nanoparticle-based therapeutics for targeting diseases that involve the mesangium of the kidney.

Heart valve tissue engineering: quo vadis?

Surgical replacement of diseased heart valves by mechanical and tissue valve substitutes is now commonplace and generally enhances survival and quality of life. However, a fundamental problem inherent to the use of existing mechanical and biological prostheses in the pediatric population is their failure to grow, repair, and remodel. A tissue engineered heart valve could, in principle, accommodate these requirements, especially somatic growth. This review provides a brief overview of the field of heart valve tissue engineering, with emphasis on recent studies and evolving concepts, especially those that establish design criteria and key hurdles that must be surmounted before clinical implementation.

Improvement of Gas Entrainment Prediction Method—Introduction of Surface Tension Effect—

A gas entrainment (GE) prediction method has been developed to establish design criteria for the largescale sodium-cooled fast reactor (JSFR) systems. The prototype of the GE prediction method was already confirmed to give reasonable gas core lengths by simple calculation procedures. However, for simplification, the surface tension effects were neglected. In this paper, the evaluation accuracy of gas core lengths is improved by introducing the surface tension effects into the prototype GE prediction method. First, the mechanical balance between gravitational, centrifugal, and surface tension forces is considered. Then, the shape of a gas core tip is approximated by a quadratic function. Finally, using the approximated gas core shape, the authors determine the gas core length satisfying the mechanical balance. This improved GE prediction method is validated by analyzing the gas core lengths observed in simple experiments. Results show that the analytical gas core lengths calculated by the improved GE prediction method become shorter in comparison to the prototype GE prediction method, and are in good agreement with the experimental data. In addition, the experimental data under different temperature and surfactant concentration conditions are reproduced by the improved GE prediction method.

Transient thermo-hydraulical/thermo-mechanical analysis of the HCLL-TBM for ITER

This paper concerns the design calculations and performance evaluation of the helium cooled lithium lead-test blanket module (HCLL-TBM) for ITER. Previous works have shown the importance of integrated multi-physics approaches for enabling correct TBM design and specifications. Particularly, this work presents the results of a transient thermo-fluid/thermal-stress analysis in which the thermo-hydraulical and the thermo-mechanical calculations are sequentially and recursively coupled. The above procedure has been used to study the thermo-mechanical behaviour of the HCLL-TBM taking into account the transient loading conditions due to the pulsed plasma operation in ITER. New finite elements (FE) models have been specifically developed for this task: all calculations have been carried out in three dimensions with representative CAD models, including detailed descriptions of all relevant TBM components. Temperature evolutions in the coolant, structural and breeder materials have been calculated. The results of the FE calculations have been analyzed with respect to thermo-hydraulics and thermo-mechanical stresses in order to verify the compliance with the established design criteria (maximum temperature in the structural material and RCC-MR rules with SDC-IC complements).

Pit water management in a mine planning cycle, olympic dam case study

Mine water management is often an afterthought in mine planning processes and can introduce significant risks to projects when studied as a stand alone component at a later stage in the mine design. Incorporation of a mine dewatering and pore pressure dissipation strategy in the early stages of mine planning is imperative in order to minimise constraints on the production schedule, to match designed pit slopes and maximise project value for an open cut mine option such as Olympic Dam. A risk-based mine planning approach was adopted during the project selection phase study whereby water management was introduced into mine planning, scheduling and the development of an operational strategy. Hydrological and hydrogeological studies and outputs were successfully integrated into the various iterations of the mine planning cycle during early selection phase to manage the potential water management risks associated with pit slope depressurisation and access to dry working conditions during rapid advancement of mining phases. An extensive network of vibrating wire piezometer sets and long-term depressurisation testing characterised aquifer conditions and demonstrated that hydraulic connectivity exists within the geological profile due to the presence of structures and resource drill holes which enhance vertical connectivity. This connectivity, along with underdrainage from mining activities contributes up to 100 m of depressurisation in low permeability units. A pit dewatering strategy incorporates the mine planning schedules and accounts for operational constraints as to the location and development of the dewatering wells, storages and pipelines. Numerical modelling generated a range of likely pit inflows and dewatering requirements with the average initial dewatering discharge likely to be 150 L/s and reduce quickly to 50 L/s after five years, depending on the premine schedule. Coupled hydrogeological and geotechnical assessments were also carried out as part of the mine planning cycle and indicate that successful dewatering will go a long way to reduce the pore pressures within key geotechnical units during the rapid mining phase where around 300 m of cover sequence is stripped in five years. However, the residual storage in the primary aquifer and the residual pore pressure in underlying low permeability units will need to be dissipated (in-pit horizontal holes) as the pit floor advances. Pit slope design angles are sensitive to depressurisation and dewatering and up to 70 per cent depressurisation of key geotechnical rock units are required. Whilst an accelerated program of aquifer dewatering supported by lithostatic unloading should drive rapid depressurisation in the lower permeability units, intervention is anticipated in key geotechnical units such as the Tregolana Shale and volcaniclastics. The extent of induced drainage will ultimately depend in part upon the mining rate and geotechnical stability requirements. Practical operability testing addressed the potential for operational constraints to mine depressurisation activities such as congestion and mining schedule development within the pit and identified that depressurisation drilling can be achieved even with reduced access availability. Mine operations and planning groups established design criteria and considered the likely inoperable periods following rainfall events of seven to 14 days to manage the base surge and minimise impact on production. In-pit surface water management options to minimise operational disruptions during and after significant rainfall events were estimated used a stochastic approach.

Evaluation of Interfacial Properties for Carbon Fiber/ Polyamide Model Composites by Means of Single Fiber Pull-Out Test

Carbon fiber reinforced thermoplastics (CFRTP) have a lot of attention for their application to mass-produced-cars. While large amount of process and material data are available for carbon fiber reinforced thermoset composites (CFRP), CFRTP dose not have enough data in manufacturing process and mechanical properties compared with CFRP. Polyamide 6 (PA6) resin is expected to the matrix of CFRTP because of its low cost, good bonding to the carbon fiber, and good moldability. In order to establish design criteria and life assessment of carbon fiber reinforced PA6 resin composite, quantitative assessment of the environmental influence on the fiber/matrix interfacial strength is needed. The single fiber pull-out test was carried out to investigate the influence of water absorption on the interfacial shear strength of PAN-based carbon fiber/polyamide 6 composites. The interfacial shear strength was 38.3MPa for dry specimen, and those of one day and one week wet specimens are 22.9 and 11.3MPa, respectively. Water absorption test was carried out in distilled water at 80°C. The fiber/matrix interfacial shear strength was severely decreased by water absorption. Dry and one day wet specimens were fractured by adhesive failure with interfacial crack. For one week wet specimens, fracture morphology was divided into two groups. For most of one week wet specimens, the crack propagated in the matrix near the fiber/matrix interface. For two of them, the crack propagated in the interface. From this difference of the fracture morphology, process of water absorption to the pull-out specimen is considered as follows. The water absorbed through the interface and degraded the interfacial shear strength. Then, absorbed water diffuse to the resin and the resin was degraded.

Thermo-hydraulical and thermo-mechanical analysis of the HCLL-TBM breeding unit

This paper concerns the latest design of the Helium Cooled Lithium-Lead (HCLL)-Test Blanket Module (TBM) according to the new dimensions of the space available for the module in the ITER equatorial ports. The performances of the proposed design are evaluated by means of new FE models of one breeding unit and the corresponding box structure. Detailed temperature and stress field distributions in each part of the structure have been obtained for nominal and accidental load conditions. The results of the FE calculations are analyzed with respect to thermal-hydraulics and thermo-mechanical stresses in order to verify the compliance with the established design criteria (maximum temperature in the structural material and SDC-IC rules). Also, the operating parameters are discussed in view of the DEMO-relevance of the proposed TBM design. Finally, possible improvements and modifications of the current design are proposed.

Regenerative French Urbanism: Sustainable Planning Strategies in Lille, Lyon, and Montpellier

Abstract Sustainability engages a complex and nuanced spectrum of issues when it shifts from the realm of architecture to that of urbanism. Individual building compliance is typically measured by objective physical design traits and performance criteria. By contrast, sustainable urban design must respond to historical, political and cultural contexts while simultaneously addressing overarching concerns such as land use and energy efficiency. The resulting urban mandate is neither formulaic nor nostalgic. Rather, it is grounded in the natural alignment of established urban design criteria—emphasizing concentrated, vital city centers as the physical, economic and social focus of urban life—with sustainable principles of compact development and controlled growth. This paper explores the adaptability of these principles to a range of urban contexts, through case studies of several French cities that have experienced significant new development in the past several decades. Planning for recent growth in Lille, ...

Operational Analysis of Water Application of a Sprinkler Irrigation System Installed in a Golf Course: Case Study

Popup sprinkler irrigation systems are usually installed in golf courses, orchards, and lawns. Evaluation of these systems is considered essential to identifying any necessary improvements. To this end some performance indicators have evolved for comparison of the existing performance with established design criteria of the system. The irrigation uniformity and application efficiency of any irrigation system are important factors which are strongly affected by pressure and wind speed. In this study, the water application uniformity, system efficiency, water application rates, jet losses, and soil infiltration characteristics were considered as the basic performance indicators. The low quarter distribution uniformity of the system varied from 43 to 57% and the application efficiency was found to be only 34–47%. The Christiansen uniformity coefficient varied from 61.7 to 68.9% for different operating pressures. More losses were found for day time irrigation than for night time irrigation. Surface runoff was...

Gate Current Noise in Ultrathin Oxide MOSFETs and Its Impact on the Performance of Analog Front-End Circuits

In future charged particle tracking systems, readout integrated circuits will be based on CMOS processes with minimum feature size in the 100 nm range. In nanoscale technologies, the reduction of the gate oxide thickness may lead to a non-negligible gate current due to direct tunneling phenomena. This leakage current, which is caused by discrete charges randomly crossing a potential barrier, yields an increase of the static power consumption for the digital section of the readout circuits and might degrade the noise performances of the analog front-end. As a consequence, in these advanced CMOS processes, an accurate characterization of the gate current noise is necessary in order to establish design criteria for detector analog front-end applications. This work presents the results of static and noise characterization of the gate-leakage current of NMOS devices belonging to a 90 nm commercial process. Data extracted from the measurements have been used to validate an analytical model for the gate current noise, which provides a useful tool for evaluating the impact of this noise source on the resolution limits achievable by low-noise charge amplifiers.