Performance-based Procedures Research Articles

Performance-based probabilistic liquefaction-induced ground settlement procedure

Performance-based procedures represent an improvement over current state-of-practice procedures that treat the assessment of seismic demand and engineering response parameters independently. Procedures used in current practice generally provide estimates of liquefaction-induced ground settlement that are inconsistent with the desired ground settlement hazard level. A recently developed probabilistic procedure to estimate liquefaction-induced ground settlement is employed to develop a new performance-based procedure that estimates ground settlement which accounts for key sources of uncertainty. The ground-motion intensity and ground settlement estimations are integrated in the proposed procedure to produce hazard curves for liquefaction-induced ground settlement. The hazard curve for ground settlement links different hazard levels with their corresponding values of ground settlement by evaluating a wide range of ground-motion intensities and site characterization parameters with their associated uncertainties. The proposed performance-based procedure also permits the evaluation of different sources of uncertainty and their effects on the ground settlement estimate.

Facilitative interpersonal skills are relevant in child therapy too, so why don't we measure them?

One of the consistent findings from psychotherapy process research has been the impact of therapist effects on patient change and the therapeutic alliance. The Facilitative Interpersonal Skills (FIS) paradigm is a task in which participants respond to standardized videos of actors playing patients in interpersonally challenging moments as if they were the therapist, which was designed to assess therapist effects. Participants’ video recorded responses are coded for eight skills: verbal fluency, emotional expressiveness, warmth/acceptance/understanding, empathy, persuasiveness, hope/positive expectations, alliance-bond capacity, and rupture-repair responsiveness. Performance-based procedures like the FIS minimize self-report bias and systematically control for client-related variability while maintaining strong clinical relevance. Research has shown that therapist FIS predicts the quality of the therapeutic alliance and outcome in adult psychotherapy. This paper describes the development and first adaptation of the FIS task using child and adolescent patients as the stimuli, and reports findings from a pilot study testing the reliability. The FIS-Child (FIS-C) task was administered to 10 therapists with a range of clinical backgrounds. Participants also completed the original FIS task and self-report measures of their empathy, social skills, and playfulness. Adequate interrater reliability was achieved on the FIS-C. There were no significant differences between participants’ ratings on the FIS-C compared to the original FIS, although there were minor differences in the correlations between the FISC and self-report measures compared to the original FIS. Findings support moving forward with utilizing the FIS-C to empirically study therapist effects that may be common factors across treatment models.

Record-to-record variability and code-compatible seismic safety-checking with limited number of records

The Italian code requires spectrum compatibility with mean spectrum for a suite of accelerograms selected for time-history analysis. Although these requirements define minimum acceptability criteria, it is likely that code-based non-linear dynamic analysis is going to be done based on limited number of records. Performance-based safety-checking provides formal basis for addressing the record-to-record variability and the epistemic uncertainties due to limited number of records and in the estimation of the seismic hazard curve. “Cloud Analysis” is a non-linear time-history analysis procedure that employs the structural response to un-scaled ground motion records and can be directly implemented in performance-based safety-checking. This paper interprets the code-based provisions in a performance-based key and applies further restrictions to spectrum-compatible record selection aiming to implement Cloud Analysis. It is shown that, by multiplying a closed-form coefficient, code-based safety ratio could be transformed into simplified performance-based safety ratio. It is shown that, as a proof of concept, if the partial safety factors in the code are set to unity, this coefficient is going to be on average slightly larger than unity. The paper provides the basis for propagating the epistemic uncertainties due to limited sample size and in the seismic hazard curve to the performance-based safety ratio both in a rigorous and simplified manner. If epistemic uncertainties are considered, the average code-based safety checking could end up being unconservative with respect to performance-based procedures when the number of records is small. However, it is shown that performance-based safety checking is possible with no extra structural analyses.

The Effect of Columns Configuration on High-rise Building Using Performance-based Design

An important point of seismic assessment is the judgment of performance limit, which is ascertaining safety framework as building life. Because the higher a multi-story building was built, the higher the risk to the earthquake loads will be. In this paper, a description of column configuration in particular performance-based procedures used for assessing of associated tall buildings is proposed because the columns' size and its configuration strongly affect the performance of the seismic structural response. This paper is aimed to determine the column's size and its proper configuration associated for seismic resistance building structures. Five-building types were modeled using various column sizes and configurations. The pushover analysis from SAP2000 was used to obtain deformation capacity. Hence, the capacity spectrum method ATC-40 and displacement coefficient method FEMA 356 were implemented in order to get the performance points of each building model. The performance evaluation results show that all structural models have a level of performance that is better than maximum expectations, which are on the IO (Immediate Occupancy) performance level. Both building structural models C and E provide the largest deformation capacity, which is able to achieve displacement targets of up to 1.6 m. However, the structure's deformation capacity is greatly affected by the column size and portal structure configuration. The capacity curve from pushover analysis shows that the largest deformation capacity is achieved by medium columns size with a target-drift up to 3%.

P.583 Polymorphisms in BDNF, AKT1, GSK3B genes: possible association with antipsychotic-induced hyperprolactinemia in schizophrenia patients

This study presents new developments for the performance-based assessment of seismically-induced slope displacements (D). Performance-based procedures enable a hazard-consistent and rational seismic design of slope systems; hence, their use in practice is appealing. However, they are not the standard in engineering practice because their use is considered too complex to be used for non-critical projects. The developments presented in this study allow the straightforward estimation of displacement hazard curves (DHC) for a wide range of slope systems subjected to earthquakes in different tectonic settings (i.e., shallow crustal, and subduction), considering a rigorous quantification of the existing uncertainties.The new developments include 1) full integration of probabilistic seismic hazard assessments (PSHA), and the estimation of DHCs, 2) automatic estimation of DHC for D models with multiple intensity measures through vector PSHA, 3) estimation of DHC for systems with contributions from multiple tectonic settings, 4) uncertainty treatment (i.e., epistemic and aleatory) on DHCs, through a logic tree scheme, 5) deaggregation of earthquake scenarios from DHCs, and 6) uncertainty quantification on DHCs through the polynomial chaos theory. The new developments are implemented in a MATLAB graphical user interface (GUI) to facilitate its use by engineers and researchers. We discuss illustrative examples and guidelines for the application of the GUI to evaluate the seismic performance of different slope systems that are affected by earthquakes from multiple tectonic settings.

New developments for the performance-based assessment of seismically-induced slope displacements

This study presents new developments for the performance-based assessment of seismically-induced slope displacements (D). Performance-based procedures enable a hazard-consistent and rational seismic design of slope systems; hence, their use in practice is appealing. However, they are not the standard in engineering practice because their use is considered too complex to be used for non-critical projects. The developments presented in this study allow the straightforward estimation of displacement hazard curves (DHC) for a wide range of slope systems subjected to earthquakes in different tectonic settings (i.e., shallow crustal, and subduction), considering a rigorous quantification of the existing uncertainties.The new developments include 1) full integration of probabilistic seismic hazard assessments (PSHA), and the estimation of DHCs, 2) automatic estimation of DHC for D models with multiple intensity measures through vector PSHA, 3) estimation of DHC for systems with contributions from multiple tectonic settings, 4) uncertainty treatment (i.e., epistemic and aleatory) on DHCs, through a logic tree scheme, 5) deaggregation of earthquake scenarios from DHCs, and 6) uncertainty quantification on DHCs through the polynomial chaos theory. The new developments are implemented in a MATLAB graphical user interface (GUI) to facilitate its use by engineers and researchers. We discuss illustrative examples and guidelines for the application of the GUI to evaluate the seismic performance of different slope systems that are affected by earthquakes from multiple tectonic settings.

Probabilistic seismic analysis of an LNG subplant

Refrigerated liquefied gas (RLG) terminals that are part of lifeline facilities must be able to withstand extreme earthquakes. A liquefied natural gas (LNG, ethylene) terminal consists of a series of process facilities connected by pipelines of various sizes. Although tanks, pipes, elbows and bolted flanges have been a major concern in terms of seismic design, generally, they have not been analysed with modern performance-based procedures. In this study, the seismic performance of pipes, elbows and bolted flanges is analysed and seismic fragility functions are presented within the performance-based earthquake engineering framework.Particular attention was paid to component resistance to leakage and loss of containment even though several different limit states were investigated. The LNG tank, support structures and pipework, including elbows and flanges, were analysed with a detailed 3D finite element model. For this purpose, we developed a mechanical model of bolted flange joints, able to predict the leakage limit state, based on experimental data. A significant effort was also devoted to identification of a leakage limit state for piping elbows, and we found the level of hoop plastic strain to be an indicator. Given the complexity of the FE model of the LNG plant, we selected the Cloud method for probabilistic seismic demand analysis, due to its advantages in terms of consistency in the seismic input and of computational savings. Then, using a series of nonlinear time history analyses, we studied the behaviour of critical components such as elbows and bolted flange joints. In order to develop fragility curves, we selected a set of 36 ground motions from a database of historic earthquake accelerations. The results of seismic analysis show that bolted flange joints remain significantly below their leakage threshold whilst elbows at the top of the LNG tank are likely to show leakage. Moreover, fragility functions were computed, based on a linear regression approach, and we deduce that elbows located on the tank platform are relatively unsafe against earthquakes. Finally, the estimated probability of loss of containment was above the probability associated with ultimate limit states involved in structural Eurocodes.

Liquefaction-induced settlement of shallow foundations on two-layered subsoil strata

Geotechnical design codes have been shifted from classical limit equilibrium analysis toward the performance-based procedures. In foundation design, settlement is the most representative parameter for its performance. Settlement of shallow foundations subjected to earthquake loading and its consequences is one of the most outstanding issues which should be considered in designing different structures. In this study, settlement of shallow footing on two-layered subsoil strata under earthquake loading is of concern. The numerical study presented in this research by means of a 3D dynamic fully coupled u-p analysis, addresses the effect of different parameters on shallow foundation settlement rested on two-layered soil. Results show that the presence of dense layer can mitigate the settlement up to 50% in comparison to uniform liquefiable layer. Putting the results of all the analyzes together, an equation was proposed in order to estimate shallow foundation settlement on two-layered subsoil.

Safety assessment of RNP AR approach procedures

The required navigation performance authorisation required (RNP AR) approach, which is one of the performance-based navigation procedures, enables safer and efficient flight operations in busy and challenging mountainous areas. The RNP system increases situational awareness of pilots because of including monitoring and alerting service on board and ensuring lateral track accuracy of up to ± 0.1 NM. In this study, RNP AR approach (RNP AR APCH) procedures which will be a solution to prevent controlled flight into terrain (CFIT) accidents are defined. CFIT accidents mostly occur in the approach and landing phase of flights because of the lack of precision approaches. Moreover, flight operational safety assessment (FOSA) methodology published for only RNP AR APCH procedures is assessed. The FOSA is a significant part of the operational authorisation for RNP AR APCH procedures and also is applied to evaluate particular cases and could be useful method for mitigating the risk of CFIT.

Modified Performance-Based Liquefaction Triggering Procedure Using Liquefaction Loading Parameter Maps

AbstractSimplified performance-based liquefaction triggering procedures have sought to address observed inconsistencies in predicted liquefaction triggering hazards across the United States resulting from conventional, pseudoprobabilistic analysis procedures. Unfortunately, current simplified performance-based procedures are limited to use with a single liquefaction triggering curve. This paper introduces a modified performance-based procedure and applies it to a different liquefaction triggering curve that is currently used by many engineering practitioners. The modified procedure is derived, and the concept of liquefaction loading parameter maps is introduced. Validation of the modified procedure against the full performance-based procedure is performed for multiple U.S. cities and soil profiles at three different return periods. The results of the validation demonstrate that the modified performance-based procedure reasonably approximates the full performance-based procedure across multiple return peri...

Estimating seismic demands for performance-based engineering of steel buildings

Author(s): Reyes, Juan Carlos | Advisor(s): Chopra, Anil K | Abstract: Earthquake engineering practice is increasingly using performance-based procedures for evaluating existing buildings and proposed designs of new buildings. Both nonlinear static and nonlinear response history analyses (RHA) are used for estimating engineering demand parameters (EDPs)--floor displacements, story drifts, internal forces, hinge rotation, etc--in performance-based engineering of buildings. Topics related to both analysis procedures are investigated in this dissertation.In the first part, the original modal pushover analysis (MPA) to estimate seismic demands due to one component of ground motion is extended to consider two horizontal components simultaneously in three-dimensional analysis of buildings, and to estimate internal forces and plastic hinge rotations directly from pushover analyses. Subsequently, the accuracy of MPA in estimating EDPs for tall buildings and unsymmetric-plan buildings is evaluated. Seismic demands for recently designed and built 48- and 62-story buildings with ductile concrete core walls--designed according to the alternative provisions of the 2001 San Francisco Building Code (SFBC)--due to an ensemble of 30 ground motions are computed by MPA and nonlinear RHA, and compared. We demonstrate that MPA procedure shows degree of accuracy that is sufficient for practical application in estimating median values of EDPs for tall buildings subjected to two horizontal components of ground motion. The accuracy of the extended MPA procedure is also evaluated for low- and medium-rise unsymmetric-plan buildings with ductile frames designed in accordance with the 1985 Uniform Building Code (UBC85) and the 2006 International Building Code (IBC06). Seismic demands are computed for six unsymmetric-plan buildings due to 39 ground motions acting simultaneously in two orthogonal horizontal directions. Comparing these results with those from nonlinear RHA, we demonstrate that MPA provides good estimates of EDPs whereas the procedures specified in the ASCE/SEI 41-06 standard and the Eurocode 8 are not satisfactory for estimating seismic demands for unsymmetric-plan buildings.The second part of the dissertation concerns nonlinear response history analysis of buildings. With the goal of developing effective procedures for selection and scaling of multi-component ground motions to be used in nonlinear RHA, a modal-pushover-based-scaling (MPS) procedure is developed in this investigation. The developed MPS procedure is an extension of the original MPS procedure for one component of ground motion to two horizontal components. In this investigation, each horizontal component of ground motion is scaled by a factor selected to match the deformation of its inelastic SDF system to a target inelastic deformation that may be estimated using a design (or response) spectrum. The properties of the inelastic SDF system are determined by pushover analysis of the building using the first-mode distribution. Based on the results for medium-rise symmetric-plan and unsymmetric-plan buildings with ductile frames, we demonstrate that the MPS procedure provides much superior results than the scaling procedure specified in the ASCE/SEI 7-05 standard.

Full-Scale Experimental Verification of Soft-Story-Only Retrofits of Wood-Frame Buildings using Hybrid Testing

The FEMA P-807 Guidelines were developed for retrofitting soft-story wood-frame buildings based on existing data, and the method had not been verified through full-scale experimental testing. This article presents two different retrofit designs based directly on the FEMA P-807 Guidelines that were examined at several different seismic intensity levels. The effects of the retrofits on damage to the upper stories were investigated. The results from the hybrid testing verify that designs following the FEMA P-807 Guidelines meet specified performance levels and appear to successfully prevent collapse at significantly higher seismic intensity levels well beyond for which they were designed. Based on the test results presented in this article, it is recommended that the soft-story-only retrofit procedure can be followed when financial or other constraints limit the retrofit from bringing the soft-story building up to current code or applying performance-based procedures.

Performance control for efficient design of double-layer grids under uniform loading

Performance control (PC) is a recently developed, observation based, design process that aims at rational and efficient selection of structural elements rather than investigating their usefulness through iterative processes. The basic notion behind PC is that structural response is mainly a function of design and detailing, rather than numerical computations. The design concept uses pre-selected target displacements and failure mechanisms as key control objectives. While elastic analysis is still the predominant design methodology for double-layer grids (DLG) and similar structures under service conditions, performance-based procedures could further enhance their functional uses up to plastic limit states. The current contribution presents a general technique for the estimation of maximum plastic displacements of twistless, orthotropic, DLG of regular formation, simply supported along the sides of a parallelogram, and subjected to monotonically increasing uniform distribution of normal nodal forces. In the interim, a new application for the uniqueness theorem has also been discussed. The proposed methodology is ideally suited for preliminary design as well as capacity analysis purposes. It lends itself well to both manual and spreadsheet computations. The applications of the proposed solutions have been illustrated through a number of generic examples. The paper does not address seismic conditions.

Performance-based design methodologies for geotechnical earthquake engineering

Performance-based design offers a number of advantages over historically common design approaches. As currently practiced, performance is most commonly evaluated in terms of system response, typically displacement-related, using traditional ground motion intensity measures defined at two or more discrete hazard levels. Such approaches do not necessarily allow all of the potential benefits of performance-based design to be realized. More recently, integral performance-based procedures that account for ground shaking hazards at all hazard levels have been developed. This paper reviews basic concepts of performance and different approaches to the implementation of performance-based design. An load and resistance factor-like methodology is described and illustrated with an example.

A Review of ASHRAE Standard 160—Criteria for Moisture Control Design Analysis in Buildings

Abstract Many of our current recommendations for moisture and condensation control are not based on quantitative analysis under a consistent set of design assumptions, even though a growing number of computer tools are beginning to make such analysis practical. To address this issue, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published ASHRAE Standard 160, “Criteria for Moisture-Control Design Analysis in Buildings,” in January 2009. The standard provides performance-based procedures and criteria for moisture design analysis for buildings. It sets criteria for moisture design loads, moisture analysis methods, and satisfactory building performance. The standard can be used for the design analysis of the building envelope or to help guide specifications for HVAC equipment and controls. Eventually, it should form the basis for prescriptive moisture design rules based on a uniform set of design assumptions and loads. It is intended to help reduce building failures in service, provide consistency in design approach and recommendations, offer more flexibility in design for moisture control and better ability to incorporate new materials, and provide greater transparency by requiring reporting of design assumptions. This paper describes the rationale behind this standard, what is in it, its potential uses, and areas of uncertainties. A standing ASHRAE Standard Project Committee has now been formed to update the standard. The paper discusses some of the main changes that are likely to occur in the next update.

Simplified Approximation Procedure for Performance-Based Evaluation of Liquefaction Potential

Performance-based procedures for evaluation of liquefaction potential have been shown to provide more consistent and accurate indications of the actual likelihood of liquefaction in areas of different seismicity than conventional procedures. The process of performing a complete site-specific performance-based evaluation of liquefaction potential, however, requires numerous calculations involving quantities that many geotechnical engineers are not familiar with. This paper shows how the results of complete performance-based analyses can be expressed in terms of a scalar parameter corresponding to a particular element of soil in a reference soil profile, and presents procedures for adjustment of that parameter to account for site-specific conditions that differ from those of the reference profile. The procedures are shown to closely approximate the results of complete site-specific performance-based evaluations. Engineers can then use mapped values of the scalar parameter, along with the recommended adjustment procedure, to realize the benefits of a performance-based evaluation without having to actually perform the performance-based calculations.

The importance of mineral filler on construction specifications

Studies have been conducted to date to demonstrate how the dust content in hot-mix-asphalt (HMA) should be accounted for in construction specifications. It may be detrimental to pavement performance if a high change in the dust content from the actual target value is not captured during HMA production. A study was conducted to determine whether the present composite pay factor (CPF) in Florida reflects the laboratory predicted loss in cracking performance. Resilient modulus, creep and strength tests, along with the University of Florida fracture mechanics model were used on 18 Superpave mixtures. Based on the analysis conducted, it was found that the current CPF in Florida did not reflect the expected loss in performance. The results showed that a 2% increase in dust can be at least as or more detrimental than 0.7% reduction in the asphalt content. However, this was not reflected in the weighted factor assigned to dust in the CPF equation. In this research, a framework to identify performance-based acceptance procedures was also presented. Ideally, this framework can be used to develop or modify construction specifications so that the expected performance of HMA can be assessed accordingly.

Drittmittel als Performanzindikator der Wissenschaftlichen Forschung

Ressourcen innerhalb und zwischen Universitaten und in der auseruniversitaren Forschung werden angesichts der Finanzknappheit im Wissenschaftssystem zunehmend in Abhangigkeit von Forschungsleistungen verteilt. Hiermit bekommen Evaluationsverfahren und die Messung von Forschungsleistungen einen neuen Stellenwert. Drittmitteleinkommen als relativ einfach zu erhebender Performanzindikator spielt in allen neuen leistungsbasierten Verteilungsverfahren eine grose Rolle. Ziel dieses Beitrags ist es, die Aussagekraft von Drittmitteln fur die Bewertung von Forschungsleistungen zu untersuchen. Auf der Grundlage von quantitativen und qualitativen Daten zu Forschungsgruppen aus drei sehr unterschiedlichen Forschungsfeldern wird der Zusammenhang von Strukturindikatoren, Drittmitteleinkommen als weiterem Inputfaktor und dem Output der wissenschaftlichen Produktion betrachtet. Hierbei zeigt sich, dass der Einsatz von Drittmitteln als Performanzindikator nur unterhalb eines von disziplinspezifischen Produktionsbedingungen bestimmten Schwellenwertes sinnvoll ist. Ferner ergibt die weitergehende Analyse, dass Forschungsperformanz mehrdimensional ist, Publikationen also nicht der einzig sinnvolle Indikator fur Performanz sein konnen. Schlieslich zeigt sich, dass die Bedingungen wissenschaftlicher Produktion zwischen den Fachgebieten so unterschiedlich sind, dass Performanzvergleiche nur innerhalb homogener Forschungsfelder sinnvoll einsetzbar sind. Abschliesend werden die forschungspolitischen Implikationen fur Forschungsfinanzierung und Forschungsevaluation diskutiert sowie weiterer Forschungsbedarf aufgezeigt.

Seismic analysis, design, and review for tall buildings

AbstractWhereas current building codes legally apply to seismic design of tall buildings, their prescriptive provisions do not adequately address many critical aspects. Performance‐based engineering provides a desirable alternative. Application of performance‐based procedures requires: an understanding of the relation between performance and nonlinear modeling; selection and manipulation of ground motions appropriate to design hazard levels; selection of appropriate nonlinear models and analysis procedures; interpretation of results to determine design quantities based on nonlinear dynamic analysis procedures; careful attention to structural details; and peer review by independent qualified experts to help assure the building official that the proposed materials and system are acceptable. These topics are discussed with an emphasis on tall buildings. Copyright © 2006 John Wiley & Sons, Ltd.

Seismic Capacity Requirements for Low-Rise Reinforced Concrete Buildings Comprised of Members Failing in Shear and in Flexure

This paper presents a method for determining required shear and flexural strengths associated with structural damage states for various levels of earthquake demand of low-rise RC buildings having a dual lateral-load resisting system. The interaction curves of the required strengths are derived for various ductility ratios based on nonlinear dynamic analyses of the singledegree- of-freedom system. Damage states of buildings controlled by both shear and flexure are evaluated by the procedure outlined by the Japanese Standard. The proposed method predicts reasonably well damage sustained by actual buildings during an earthquake. The proposed method can be used to develop performance-based seismic evaluation and rehabilitation procedures of lowrise RC buildings having a dual lateral-load resisting system.