Search

In this paper, serviceability limit state reliability analysis of a railway embankment on soft clay is conducted using probabilistic approach. The aim of this study is to evaluate how uncertainties in soil parameters and geometry affect the reliability of the design with respect to maintenance need assessment. The studied clay deposit is located in Perniö, Finland. Due to intensive laboratory testing, the coefficient of variation of geotechnical parameters for each clay layer could be estimated. Two performance functions were defined based on maximum settlement and maximum change in longitudinal gradient given in Finnish guidelines. In the settlement calculation, both primary and secondary consolidation were considered. According to the results, uncertainty in gradient changes is more critical and also more challenging to assess compared to uncertainty in total settlement. All in all, reliability analysis will clearly support the assessment of maintenance need.

The design of structures is more and more directed towards the entire lifetime design with multiple concurrent objectives. Apart from durability, the most important factor in the whole life design of reinforced and, in particular, prestressed concrete bridges, is the Service Limit State. From this point of view, prestressed concrete bridges are very sensitive to long-term increase of deflections. A survey of many bridges monitored in various countries showed that all of them have experienced similar deflection histories. The intention of the paper is to describe methods and mathematical models which should be used for reliable prediction of long-term behaviour of prestressed concrete bridges. The comparisons between results of numerical simulations and measurement data will be also mentioned.

A new procedure is proposed for design of individual drilled shafts in shale at service limit states. The procedure utilizes t-z analyses and adopts the factored strength approach to account for variability and uncertainty in the design method and associated input parameters. The resistance factors used in the procedure were calibrated using a finite-element code to model load transfer in drilled shafts and Monte Carlo simulations. The variability and uncertainty considered for calibration of the resistance factors were derived from full-scale load tests performed on drilled shafts founded in shales in the central United States. The calibrated resistance factors generally range between 0.1 and 0.4, depending upon the uncertainty in the shale uniaxial compressive strength. Such values are substantially less than those commonly used in current practice, but reasonably reflect the collective variability and uncertainty present for design of drilled shafts in shale. The primary appeal of the proposed procedure is that it eliminates the need to design for the service limit state on a case-by-case basis.

This paper discusses an experimental study on the pipe rehabilitation method for the purpose of establishing a fundamental design standard. In this method, as the new pipe is directly inserted into the aging pipe, there are several possibilities in terms of cost reduction. It is not clear how the damaged outer pipe mechanically influences the inner pipe through interaction with the surrounding soil when an external force is applied to the ground. In this study, centrifuge model tests for the buried pipe are carried out. The test results indicated that deformation mode of the new pipe is largely dependent on the damage level of the outer pipe. When the damage state is not serious, the outer pipe protects the inner pipe from deforming and behaves positively. On the other hand, the outer pipe, if at ultimate limit state, has almost no influence on the mechanical behavior of the inner pipe. Additionally, the concentration of stress within the inner pipe tends to occur at the position where there is cracking of the outer pipe in a certain damaged condition.

Fragility analysis is one of the most popular tools for the computation of the probability of reaching each investigated limit state for a given value of the external load intensity. Because of its versatility and computational efficiency, fragility analysis is particularly appropriate for regional loss estimations and risk analyses. Several different techniques have been proposed in the literature to compute the fragility of buildings and bridges. However, most of these techniques rely on simplifications and assumptions which, in some cases, are made more for analytical convenience than for adherence to reality. This paper investigates the effect of three of these common assumptions made on the engineering demand parameters for the case of seismic fragility analyses of bridges: (1) the marginal distribution is lognormal, (2) the median of such distribution follows a power law of the seismic intensity measure of choice, (3) the dispersion of such distribution is constant for any value of the intensity measure. Numerical analyses have been performed running extensive Monte Carlo simulations on computational clusters, focusing on structural models of different complexity. The results suggest that assumption (1) is not realistic in general, but it does not induce a significant error on the final results, whereas assumptions (2) and (3) corrupt significantly the quality of the results, introducing substantial errors. A comprehensive methodology for the assessment of fragility curves for structural components and systems is then proposed, which does not rely on the above mentioned assumptions.

A numerical approach to safety estimation of the plate-girder bending structures from the shakedown theory point of view is considered. In the analysis the uncertainties of the physical and geometrical structure’s parameters and also the load parameters have been taken into account. It has been assumed that the structure is subjected to the dead load and variable live loads. The structure’s parameters uncertainties as well as the load magnitude are treated as fuzzy variables or mutually independent random variables. On the basis of the theory of the yield lines and the kinematic formulation of the shakedown problem the limit state function is being built. From this follows that some structural and material parameters such as the plate thickness, plate reinforcement, girder cross sections and yield point are hidden in the limit moments. In case of describing the load parameters by random variables as the safety measure the Hasofer-Lind reliability index is chosen. If all uncertain parameters which appear in the limit state functions are treated as fuzzy variables the dominant failure mechanism and the minimum load factor for the non-shakedown which correspond to them can be obtained by applying -level optimization. The shakedown analysis of a two-span plate-girder has been done and the results have been presented. The main advantage of presented method is that it can be applied without a need for developing special software. It seems to be an effective approach to safety analysis of industrial roof and highway bridges.

Severalnationalsteeldesignstandards allow,inprinciple, theuseofinelastic system analysis to check the integrity of a steel structural system. However, system reliability considerations have yet to be implemented in any rational way in such design-byinelastic analysis methods. This paper considers a representative steel moment frame subjected to combined gravity and wind loads. The frame is designed using secondorder inelastic analysis with a set of postulated system resistance factors. The probabilities of occurrence of strength and serviceability limit states are evaluated. The effects on these limit state probabilities of system resistance factor and wind-to-gravity load ratio are examined.

This paper takes the bridge of the A7 block in the national freeway (Ganzhou to Chongyi) as an example. According to its practical statistical data, the material properties and deterministic parameters are treated as random variables. The distribution function and statistical parameters of the random variables are concluded through a large number of numerical simulations. The ultimate limit state equation is derived by strictly adhering to the load and capacity formula requirements in Chinese highway bridge design specifications. The reliability index for flexural capacity is calculated with the Monte Carlo method and the sensitivity analysis of key parameters is carried out. Additionally, the suggestions for construction quality control are given out.

The excavation face stability of shield tunnel under seepage condition was studied by 3D numerical simulation. By using elasto-plastic deformation/seepage finite element analysis, the deformation process when support pressure reduces from earth pressure at rest to limit state under seepage condition was obtained, and the failure mechanism of tunnel face and the limit support pressure were determined. The influence of the cohesion and friction angle of soil on the failure mechanism of tunnel face and limit support pressure under specific water table line were investigated. The results showed that the soil strength parameters affect the value of limit support pressure; however, only the friction angle of soil would change the failure mechanism obviously, but the soil cohesion would not. Furthermore, the influence of the water level change which is caused by tide on the face stability was studied. The results showed that the change of water table leads to the redistribution of pore water pressure around the tunnel face and results in the fluctuation of the limit support pressure.

One of popular offshore wind turbine foundations, monopile has been largely used because of their cheapness and constructability. Monopile is subjected by large cyclic lateral loadings such as wind, wave and current. The P-y curve method which represents a relationship between lateral pile displacement and passive soil resistance along the leading face of the pile is known as a highly reasonable method to analyses lateral behaviors of pile. Performing reliability analysis of a monopile foundation using nonlinear p-y curves is difficult because the limit state functions (LSF) of pile head deformation and rotation angle of pile are in implicit forms. To solve such problem with implicit LSF, a response surface method (RSM) could be used. Basic concept of RSM is to approximate the limit state boundary using an explicit function of the random variables. In case of using RSM, reliability analysis could be very simple, but the accuracy of analysis due to approximation depends much on the linearity of the LSF and on the distance of the axial points in the failure space. This paper investigates the best combinations of the RSM techniques with a reliability analysis of monopile for an offshore wind foundation.

The Strength I Limit State of American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) specification deals with the failure probabilities of the combination of non-extreme loads. This design limit state equation (DLSE) has been fully calibrated for dead load and live load by using the reliability-based approach in previous research. However, most of other DLSEs, including the extreme event I and II, with certain probability-based concepts considered, have not yet been fully calibrated by using the reliability-based approach. This paper presents an evaluation of the bridge reliabilities under the limit state of Extreme Event I combination of dead load, live load and earthquake load, by using a force-based and a displacement-based approach on a set of nine simplified bridge models. Results show that the displacement-based approach came up with more convergent and accurate reliabilities for selected models.

A proper foundation design is crucial for the structural stability of offshore wind turbines (OWT) in the severe ocean environments. As one of the typical foundation types for OWT, the high-rise pile cap foundation has been utilized in wind farms of China. In this study, a 3-dimensional finite element model for simulating the pile-soil interaction subjected to multi-axis complex loads is proposed and verified with existing experimental data. The bearing capacity of the high-rise pile cap foundation under various ultimate limit state (ULS) conditions is investigated. Local scour usually occurs around the pile and significantly reduces the bearing capacity of the foundation. Numerical simulation shows that scour could amplify the lateral displacement and tilt of the foundation.

The American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Specification for bridges has its strength design limit state formulated and fully calibrated using the reliability-based approach. The extreme event design limit states, however, are constructed by combining the non-extreme load effects with the independently established extreme hazard load effects through professional judgment. Its margin of safety and adequacy could not be assessed quantitatively. A research project sponsored by the Federal Highway Administration (FHWA) has been carried out to explore principles and approaches for establishing multiple-hazard (MH)-LRFD based on the established rationale and reliability-based methodology of the AASHTO LRFD. An analytical framework has been established to consider the non-extreme and extreme loads on a common reliability-based platform. This paper will describe the formulation of specific extreme event design limit state (e.g. the limit state for non-extreme load with the earthquake load effects) by using the all-hazard, reliability-based approach. Future challenges towards the development of a comprehensive MH-LRFD will be described.

Reinforced concrete (RC) bridge columns with inadequate lap splices in the longitudinal reinforcement are very vulnerable. They are even more critical in corrosive environments. Corrosion of steel bars decreases the steel section, reduces ductility, and deteriorates the bond between the steel reinforcing bars and the surrounding concrete. The base of a bridge pier, where the main reinforcing bars are lap spliced with starter bars, is a bond-critical region in RC bridges. This paper presents a model for estimation of the stress at corroded lap-spliced bars for tension-controlled RC column sections. The amount of stress in the steel bars at the ultimate limit state was estimated based on the experimental data of bond stress between the steel bars and concrete. Using the bond strength of corroded and non-corroded steel bars, stress of corroded lap-spliced bar is expressed in terms of corrosion rate and the original yielding strength. The results of this investigation suggest that corrosion of lap-spliced steel bars has significant impact on the load transfer between the lap-spliced bars and, consequently, drastic decrease in the flexural capacity of bridge columns.

Pullout tests for geosynthetics were developed to support the design of MSE walls to calculate maximum force required for internal stability calculation. In this case, the stability of the system at ultimate or limit state was of concern and results were reported in terms of coefficient of interaction (Ci) for a given geosynthetic and soil interface. However, to quantify the performance of geosynthetics used in flexible pavements, the soil-geosynthetic interface characteristics at low displacement magnitude is important. An analytical model was proposed by Gupta (2009) to assess the performance of soil-geosynthetic interaction and a new parameter to quantify soilgeosynthetic interaction (KSGI) was defined. This parameter is a function of yield shear stress and confined stiffness of the geosynthetic which can be obtained from a pullout test. The quantification of this new parameter required test equipment which would be able to define the low displacement behavior of soil-geosynthetic interfaces. However, the conventional pullout box available in most laboratories are capable of predicting the ultimate pullout force as required for MSE wall design which require long testing times. To reduce the testing times and to predict the soil-geosynthetic interface characteristics at low displacements, new pullout test equipment was developed which allows testing geosynthetics for reinforced pavement application at low displacement magnitudes. This paper describes the development of new pullout test equipment and discusses the interpretation of test results for a planar geosynthetic specimen to calibrate the proposed parameter based on the analytical model. Finally, the effect of geosynthetic orientation in the pullout equipment on the model parameters and its implication on design of reinforced pavements is discussed.

When the performance function (or limit state) is a numerical model without an explicit form, reliability analysis based on this limit state is often difficult to perform. In this paper, a series of moment methods that is built on the solutions obtained from Plaxis T M , a commercially available finite element code, is adopted for probabilistic evaluation of serviceability failure in a braced excavation. The accuracy of the computed reliability index and probability of failure tends to increase when the higher-order moments are considered. In addition, the effect of spatial variability of soil parameters on the computed probability of serviceability failure is investigated. A well documented case history of a braced excavation in clay is analyzed, and the results show that the moment methods are effective and easy to apply for computing failure probability.

Sustainable engineering requires that engineering products are not only socially acceptable, economically feasible, and environmentally friendly, but also safe against all possible serviceability and ultimate limit states. Laterally loaded piles are mostly designed against the serviceability limit state of excessive lateral deflection. This study takes into account the uncertainties associated with the response of laterally loaded piles and focuses on their load and resistance factor design based on the serviceability limit state of excessive lateral deflection. Resistance factors are obtained for laterally loaded piles embedded in clay deposits in which the soil properties are assumed to be random variables. Pile capacities are determined based on a specified allowable lateral deflection at the pile head. The pile load-displacement curves are generated using the p-y method. Model uncertainties and bias factors are incorporated in the analysis. The uncertainties associated with the lateral capacity, for a specified lateral head deflection, are quantified, and the probability distribution of the lateral capacity is determined using Monte Carlo simulations. The applied dead and live loads are assumed to follow normal and lognormal distributions, respectively. First order reliability analysis is then performed using the distributions of loads and capacity to determine the load and resistance factors.

The bearing capacity of super-long pile foundation has not achieved the limit state during the force process, considering only the calculation method of the limit state of pile foundation bearing capacity can't meet the design need. In this paper, considers the combined influence of vertical and horizontal load on pile foundation, studies the interaction relationship between pile and oil bearing the pile load, explores the change law of pile body bearing load and resistance by using two method of experimental analysis and numerical simulation. Finally the author put forward the calculation method of the pile under the combined action of the vertical and horizontal load combining with the computer programming.

By studying the essential relationship between ultimate and serviceability limit states index, the method that takes deflection-to-span ratio as evaluation criteria for traffic ability is proposed. Specifically, using the parametric design language of ANSYS, the finite-element model of beam bridge is established rapidly, and the model is modified by analyzing the deflection result. Then using the modified model, simulation experiments are carried out, and the deflection-to-span ratio of bridge under the vehicle load are worked out. Finally based on previous work, a set of evaluation standards are determined and used to evaluate the vehicle trafficability on bridge.

Diaphragm wall is commonly used as retaining structure in foundations of subway stations. The stability of slurry trench excavated during construction becomes a major concern. Field cases with the geology that a sand layer of low stability is sandwiched between two relatively stronger clays are often encountered. Because layers above and beneath are impermeable clays, confined water pressure may exist. The local stability in terms of this special geology needs to be carefully investigated. In this paper, the problem is foremost simplified to be modeled as a sand layer compressed between two rigid plates. Hyperbolic partial differential equations are established assuming the sand layer, which is rigid plastic conforming to Mohr-Coulomb yield criteria, is a limit state. The equations are then solved to obtain the theoretical solution of stress distribution on the trench surface so that a simplified formula to compute factor of safety of local stability is derived. Finally, a case history is presented and the validation of the formula is verified by numerical analysis. The method proposed by this paper successfully predicts the failure pattern of the trench face and can be applied in practice.

This paper studies the design method for the dynamic scale model of a pedestrian footbridge. A typical pedestrian footbridge was taken as the prototype and the actual structural properties and dynamic mechanics theoretical analysis based on the dynamic similarity theory for the scaled test model was used so as to deduce structurally similar ratio parameters in the scale model. Then, combined with the practical feasibility, the model is designed and produced. Compared with the dynamic field test, the finite element method analysis shows that the dynamic properties of the scaled model are very similar to the actual prototype. This designed scale model can satisfy the study on the dynamic response of pedestrian footbridges under pedestrian loads or ambient excitation. This design method for the dynamic scale model of pedestrian footbridges supplies a new approach for the study on vibration serviceability of pedestrian footbridges. In current civil engineering construction, more economic and aesthetic factors are considered in the design of all types of buildings and bridges. With the development of calculation methods in the designs and with the widespread use of lightweight and high strength structural materials, these structures are becoming larger, lighter weight, more flexible and lower damping. Although the static performance of these structures can satisfy classical structural requirements, such as bearing capacity and deformation, it brings about another problem. Its dynamic performance of serviceability limit state, especially excessive man-induced vibration of the pedestrian bridge by the overcrowded pedestrian load, will cause the people to feel uncomfortable, or even nervous and panic, while they are walking along the bridges. Man-induced vibration of footbridge structures has been researched for a period of time both at home and abroad, but most of the research is in the form of theoretical studies. For example, Jacobs, Skorecki and Charnley have researched the pedestrian’s vertical load under normal walking and other forms (Jacobs 1972). J.E. Wheeler has proposed that human-induced vibration of footbridges can be treated as forced vibration (Wheeler, 1982). The pedestrian’s walk load relates to its movement

In areas with significant seismic activity, earthquake-induced loading effects may constitute the major portion of the design loads on foundations. However, very few attempts have been made to apply reliability-based design concepts on footings under seismic loads. Therefore, this study aims at contributing to the reliability-based design methodology by estimating the resistance factors for shallow foundations in cohesionless soils under earthquake loads for the ultimate limit state (ULS), which is defined as the condition in which the seismic bearing capacity is equal to the design load including dynamic effects. The uncertainties in both the load and the capacity are considered. To evaluate the variation of the reliability index ( ) with respect to each significant design parameter, a parametric study was conducted using First Order Reliability Method (FORM) and Markov Chain Monte Carlo simulations. These results were used to select the appropriate domains within the most influential design parameters for the calibration of the simplified RBD equations that can be presented for general use. The target reliability index for calibration, which turned out to be significantly smaller than that for static loading conditions, is selected after examining the range of reliability levels implicit in existing deterministic foundation designs. The resulting resistance factors are presented in the form of design charts that can be readily applied in foundation engineering practice.

For excavations in built-up areas with deep deposits of soft clays, it is essential to control ground movements to minimize damage to adjacent structures and facilities. This is commonly carried out by controlling the deflections of the retaining wall system. The limiting wall deflection or serviceability limit state is typically taken to be a percentage of the excavation height. In this study, extensive plane strain finite element analyses have been carried out to examine the excavation-induced wall deflections for a deep deposit of soft clay supported by diaphragm walls and bracing. Based on the numerical results, two polynomial regression approaches were used to develop the equations for estimating the maximum wall deflection. This paper describes how the developed equations can be used to perform reliability analysis of the diaphragm wall serviceability limit state to estimate the probability of exceeding the limiting wall deflection. Accepted version

The design of foundations should satisfy various serviceability performance requirements. A structural foundation may concurrently experience vertical displacement, horizontal displacement, and angular distortion. While the limiting value of a single displacement has been studied, the limiting values of multiple displacements when they occur simultaneously have not yet been well studied. The objectives of this paper are to determine the limiting tolerable displacements when multiple movement components occur and to propose a composite limiting tolerable displacement criterion involving both vertical and horizontal displacements. To determine the limiting tolerable displacements for foundations subject to movements in multiple directions, performance information of 280 bridges with either vertical displacement and/or horizontal displacement has been collected and evaluated. Limiting tolerable displacements are determined by using a fragility curve to represent the cumulative probability distribution. The limiting tolerable vertical displacement and horizontal displacement when they occur concurrently are found to be smaller than their respective limiting values when only one component occurs. Both the observed intolerable horizontal displacement and limiting horizontal displacement are smaller than the corresponding vertical displacements of the same category of bridges. A linear function between the limiting vertical and horizontal displacements is proposed. The sum of two dimensionless limiting displacement terms is equal to 1.0. The composite function is modified to allow for construction tolerances in both vertical and horizontal directions. The characteristic tolerable displacements for limit state design or the allowable displacements for conventional design in both vertical and horizontal directions can be obtained based on the composite function. INTRODUCTION Geotechnical limit state design methodologies were advanced substantially in the past two decades (e.g. Becker 1996; Phoon et al. 2003a, 2003b; Honjo 2011; Wang et al. 2011). In geotechnical design, several serviceability requirements have to be satisfied, including limits in the vertical displacement, horizontal displacement, and angular distortion or differential settlement of the structural foundation (e.g. Zhang & Ng 2005; Zhang & Phoon 2006; Paikowsky & Lu 2006). Most engineering design codes provide these limits without specifying whether multiple displacement components occur concurrently or not (e.g. AASHTO 1997; CEN 2001). The traditional limiting displacement surface involving three limiting displacement variables is shown in Figure 1. The three variables are assumed to be independent. The physical processes that cause serviceability problems are very complex. Different types of displacement may interact with each other. For example, the stresses in a structural element that lead to serviceability problems are functions of the displacement components (i.e., vertical

This paper focuses on the Bayesian probabilistic modelling of uncertainty in the evaluation of drained sand strength (i.e., friction angle) and stiffness of natural sands in-situ, as evaluated using the cone penetration test (CPT), and on the probabilistic prediction of loadinginduced settlements. For the sand strength, two special datasets are compiled from undisturbed (frozen) sands that were tested in triaxial compression following thawing. For stiffness, equivalent Young’’s moduli were back-calculated from full-scale footing load tests on sands via elastic continuum theory. Transformation uncertainty is parameterized by means of model factors, which can be directly implemented in geotechnical limit state design for any user-defined target reliability level.

This paper proposes a systematic approach to design a buried cross-country steel pipeline for oil transportation, based on limit states of the pipeline in operation. Yield and buckling due to primary loads and secondary loads are considered in the limit state design. A procedure to evaluate limit states in accordance with stress and strain criteria is proposed when the pipeline is applied with factored loads. The evaluated limits include the maximum stress limit for finite element analysis (FEA) with beam-elements and the equivalent stress and strain limit for FEA with 3D solid elements. The soil conditions along the pipeline are classified into three different types. Soil is represented by discrete bilinear springs for the beam-element pipeline model and represented by extended Drucker-Prager model for the 3D solid element model. The sensitivities of the limit states to the soil conditions and pipeline bend parameters were studied. Mitigation measures are taken to make the pipeline meet the proposed limit state evaluation criteria. The cost and constructibility are taken into account to expand the beam-element model to the 3D solid element model.

Research studies examining buried pipes cannot rely on computational work alone, and physical experiments are needed for credible evaluation of buried pipe performance at service and ultimate loads. Specialized testing facilities are described which can be used to undertake buried pipe experiments on structures up to 10 m span at shallow cover, and pipes of 0.6 m diameter or less up to 1000 kPa overburden pressure (about 50 m burial). The capabilities include service load testing under real vehicles, and testing to ultimate limit states under simulated axle loads of up to 2000 kN (about 9 times the normal service load for a tandem axle design truck). Use of the facility is briefly illustrated through reference to six different projects on pipes and culverts installed using conventional and trenchless construction techniques.

The application of reinforced concrete trough girders in urban light railway reduces the noises that affect the neighborhood, which also alleviates the traffic problems. However, constraint torsional problems will be caused by the swaying force of the train; therefore more reasonable reinforcement methods should be used. Girders under constraint torsion were researched to interpret their stress states and mechanism of fractures based on the limit state analysis method. Warping, normal stress, and shearing strength distributions are interpreted, and a new mechanics analysis method is put forward. Then the warping moment is translated into moments by integrating the warping normal stress in the webs and plate separately and doing derivations of the integral. Combined with the bending moment bearing capacity calculation formula, the torsional limit bearing capacity formula for trough girders under constraint torsion is primarily established. The ultimate torque from the formula agrees with both the test results in the existing references and the simulated results from ABAQUS software. The results exhibit significant guidance for engineering applications.

This paper sets out the principles of a limit state design approach to design a pile or piled raft foundation system for tall buildings, and involves three sets of analyses: 1. An overall stability analysis in which the resistances of the foundation components are reduced by the appropriate geotechnical reduction factor and the ultimate limit state (ULS) load combinations are applied. 2. A serviceability analysis, in which the best-estimate (unfactored) values foundation resistances and stiffnesses are employed and the serviceability limit state (SLS) loads are applied. 3. An analysis to obtain foundation loads, moments and shears for structural design of the foundation system. The importance of appropriate parameter selection and load testing is emphasized. The approach is illustrated via its application to a high-rise building in Korea.

Active transportation bridges carry non-motorised modes, principally cyclists, pedestrians, equestrians, stock animals and native fauna. Designers must consider aesthetics, collision risk, the user envelope, loads, limit state criteria, deflections and dynamic behaviour, access requirements (including the mobility impaired), security against errant objects, railings, curbs and balustrades. These issues are explored via several recent bridge developments in Australia. Design references considered during the design of Australian active transportation bridges are discussed and compared with the predominant codes of practice adopted in Europe and the USA.

This paper presents a robust Monte Carlo Simulation method that can be applied to the analysis of the load-deflection behavior for laterally loaded piles considering various sources of uncertainties arising from soil properties, analytical model, and p-y criteria. In particular, soil properties needed as input for determining site specific p-y curves could be modeled as random fields. In the simulation process, a large number of random samples are generated as input, and uncertainties arising from inputs and model errors are considered. Performance criteria on the basis of service limit state (i.e., allowable deflection at working loads) and strength limit state (i.e., capacity defined at the specified limiting deflection) can be evaluated for each random sample. The probability of failure, in which failure is defined as not meeting performance criteria, is calculated by the number of failures divided by the number of random samples. A design example is presented at the end of paper to demonstrate practical applications of the developed Monte Carlo simulation method.

A variety of probabilistic approaches can be applied when performing levee underseepage analyses, as part of larger assessments of the reliability or probability of failure of a levee system. Historically, much of the work that has been conducted in this area has used probabilistic approaches that utilize a mean value first order second moment (MVFOSM) technique, due to the inherent simplicity of this probabilistic approach. This paper investigates the effect of three probabilistic approaches for assessing the likelihood of failure of a levee via an underseepage mechanism: MVFOSM, advanced first order second moment (AFOSM), and Monte Carlo simulation (MCS). For each of these approaches, two limit state criteria are explored: safety margin and safety factor. Analyses are conducted in accordance with the current U.S. Army Corps of Engineers levee design code, and representative results from some classic USACE design cases are presented. For the various design cases that were examined, results were found to be sensitive to both the probabilistic approach that was utilized and the limit state criterion that was selected. The results provide useful guidance for practicing engineers that are trying to select a probabilistic approach for these types of analyses that is both accurate and as computationally efficient as possible.

With the rapid construction of China's long-distance natural gas pipelines, it is inevitable that in many regions the high pressure pipes are laid parallel and work at the same time. Once one of the pipelines explodes caused by the defects on the pipe body, the third-party damage, or the geological disaster etc., the blast shock wave and the combustion radiant heat may lead to a chain failure reaction to the parallel pipe. This paper focuses on the explosion impact loading, an interaction mode among explosion loading, soil and gas transmission pipeline is established. In order to find out the main factors which influence the security conditions of parallel laying pipelines, the relationships between pipe’s laying space, wall thickness and internal pressure under blast loading are obtained by using LS-DYNA finite element software, accordingly, the limit state of the parallel laying pipelines would be determined. The study will give the theory adding of the parallel laying design of long-distance gas transmission pipelines, and the results have certain reference value to the study and formulation of protection measures.

The traditional shield construction technology has many defects, such as intensive labor in the process of assembling segments, high cost of the bolts, cannot stand inner water pressure directly and so on, so the shield tunnel cannot be applied in the field of tunnels rapidly that can stand inner water pressure. In recent years, post-tensioned pre-stress technology of concrete has been introduced in the production of shield tunneling segments and the assembly of segments at home and abroad, which extend the shield tunnels application in the hydraulic field. Based on the literatures and the existent researches, the paper takes the formation of a region in Beijing as the engineering background. Firstly, according to the load-structure method, the probability-based limit state design and the concept of prestressing degree, prestressed and precast concrete segments have been designed for a water conveyance tunnel. Secondly, in reference to the prestressing technology of domestic tunnel standing inner water pressure, a encircled anchorage technology was chosen for use. Meanwhile, in order to reduce the testing cost, these existing segment molds were transformed to produce these segments to meet the testing requirements. Thirdly, it was the first time to carry out the water pressure test for a full-scale and horizontal model of prestressed and precast concrete segmental lining in China and the results were satisfactory and could meet the design requirements. In the end, the mechanical properties of prestressed and precast concrete segmental lining at 0.5 MPa inner water pressure were analyzed by the three-dimensional finite element method and the theoretical results approached the full-scale experimental results. Some promising research results were obtained.

This paper focuses on the statistical characterization and stochastic modeling of the load-displacement behavior of full-scale quasi-square footings. The study relies on a large and comprehensive field database of 66 full-scale footings subjected to vertical loading on 4 different soil types (sands, silts, intact clays, fissured clays) with CPT cone resistances available for each site. The performance of 2 analytical load-displacement models in replicating empirical field data is assessed comparatively through statistical modeling of load-displacement data. Correlation between model parameters is investigated and replicated using copula theory. Following the identification of best-performance models for each soil type, loaddisplacement curves are simulated stochastically. The influence of soil type on statistical properties and modelling details are discussed. Best-performing configurations of modelling options are provided for practical implementation in geotechnical limit state design.

The reliability-based design (RBD) of shallow foundations in cohesionless soils under drained compression loading is examined for the serviceability limit state (SLS). This SLS is defined when the compression capacity at the allowable settlement limit imposed by the structure is equal to the applied load. The uncertainties in both the load and the capacity sides are considered. A Monte Carlo simulation-based parametric study indicates that the most influential parameters on the reliability index are the statistics of the effective stress friction angle and the ratio of the 50-year snow load to total load, where snow is present. These results were used to select the appropriate domains for the calibration of the simplified RBD equations that can be presented for general use. The target reliability index for calibration was selected after examining the range of reliability levels implicit in existing deterministic foundation designs. The resulting resistance factors are tabulated in a form that can be applied readily in foundation engineering practice.

The design and construction of deep excavations in urban environment is often governed by serviceability limit state related to the risk of damage to adjacent buildings. In current practice, the assessment of excavation-induced building damage has focused on a deterministic approach. This paper presents a component/system reliability analysis framework to assess the probability that specified threshold design criteria for multiple serviceability limit states are exceeded. A recently developed Bayesian probabilistic framework is used to update the predictions of ground movements in the later stages of excavation based on the recorded deformation measurements. An example is presented to show how the serviceability performance for excavation problems can be assessed based on the component/system reliability analysis. © 2011 ASCE.

Considering the facts that the parameters of tunnel lining structures are random, that the distributions are various, and that the limit state functions are highly nonlinear, this paper estimates and presents the practical parameters of tunnel lining structures. The calculations are formulated in the framework of the information entropy and maximal entropy principle, so that the actual parameters are obtained. The failure probability and the reliability index are calculated using the parameters based on the Monte-Carlo direct sampling method. Then the stability of tunnel lining structure is evaluated by using the reliability index. According to the practical engineering, an example is given. The results, which are calculated by the Monte-Carlo direct sampling method and maximal entropy principle for tunnel lining structure, are more scientific and reliable. The present method, with a high precision and a fast velocity, is suitable for similar parameter estimation and reliability calculation.

In a collaborative effort between NEES TIPS, NIED in Japan, and the NEES Nonstructural Grand Challenge project, a 5-story steel moment frame building will be shaken at the E-Defense facility in Japan. The specimen will be shaken both with and without triple friction pendulum isolators. Nonstructural components including interior walls, ceilings, piping, and concrete cladding panels will be constructed and in the specimen. The isolated specimen will be shaken to a suite of motions representing frequent, design/L2, and MCE/L3 level motions. The tests represent the grandest showcase of the benefit of seismic isolation technology to date, and the primary objective of the tests is to demonstrate that damage free performance can be targeted and achieved against an MCE/L3 earthquake. Limit state tests will illustrate the performance when the demands exceed the displacement capacity of the bearings. The tests will take place over a 3-week time frame in August 2011, with 4 days of shaking anticipated.

The objective of the presented study is to evaluate the sensitivities of the random variables and Average Daily Truck Traffic (ADTT) on the evaluated reliability of bridges. The reliability analysis is carried out for the Strength I Limit State in the AASHTO LRFD Bridge Design Specification. The Weigh-In-Motion (WIM) data recorded at 24 WIM stations in Missouri are processed and used as an input to simulate realistic live loads due to truck traffic. Gumbel Type I extreme value distribution is used to represent daily maximum positive moments and extreme value theory is used to project the daily maximum values to the maximum values in 75 years of bridge lifespan. Sensitivity analysis is conducted to understand the relative effects of random variables and ADTT on the calculated reliability index. The result shows that the ADTT affects the reliability index as sensitively as other random variables, such as dead load, girder distribution factor, and dynamic impact factor. Hence, explicit consideration of uncertainties in ADTT is suggested for future calibration studies. Alternatively, the reliability index needs to be assessed conditioned on deterministic ADTT.

Improved design methods have led to the use of more slender structural elements in the construction of many newly built structures, especially office floors. These floors satisfy ultimate limit state criteria but can attract complaints arising from excessive human-induced vibrations. Active vibration control is a technology that has been shown to significantly reduce the level of response in this situation. This paper investigates the potential increases in slenderness and associated materials savings that can be realised whilst adhering to the vibration serviceability limits through the implementation of an active vibration control system. The decentralised control setup used was found to realise significant material savings whilst still achieving desirable vibration performance.

A structural risk evaluation methodology is introduced in this paper for the offshore platforms against major hazard events (hurricanes and earthquakes) during the operating life of the platforms. The primary objective is to evaluate the risk level from the major hazard events to identify possible risk reduction solutions. Firstly a non-linear progressive collapse analysis approach is presented to investigate the platform capacity to resist the loads imposed by major hazard events. The structural reliability method is then proposed to estimate the probability of platform failure under major hazard events. The platform failure limit state function is defined in terms of hazard loads and platform capacity. Uncertainties are included in the parameters associated with hazard loads and platform capacity. Finally the platform failure consequence and the probability of platform failure are combined to determine the platform risk associated with the major hazard events. Case studies are presented to illustrate the application of the developed structural risk evaluation approach.