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In the current research work, the shear capacity of the cold-formed steel (CFS) three-bolted clip angle (CA) beam-to-column moment connection (3BM) is investigated with 45 laboratory test results. The 3BM connection comprises a three-bolted CA connector that connects the web portions and a bolted flange cleat (FC) that connects the flange portions of the beam and column; in comparison, the three-bolted shear connection (3BS) connects only the web portions of the beam and column. The presence of the FC improved the shear strength of the 3BM connection over the 3BS connection and it is quantified using a coefficient called the "rigidity factor (β)." A shift in the failure mode of CAs from shear local buckling in a 3BS connection to tearing failure in a 3BM connection was observed as the FC resists beam torsional deformation and delays the early local buckling of the CA. The existing design shear equation of the 3BS connection is improved by expressing it as a function of CA failure modes. Following the same trend, the existing design shear method for the CFS moment connection is improved by incorporating the failure modes of the CA boundary conditions along with the geometric and material properties of both the CA and FC for the present 3BM connection. In addition, an empirical shear design equation is suggested for the 3BM connection. The design factors of the proposed 3BM shear equations for load and resistance factor design, limit state design, and allowable strength design methods were evaluated from the reliability study. [ABSTRACT FROM AUTHOR]

Energy piles are gaining popularity worldwide as both pile foundations and ground source heat producers. While considerable research has been conducted on energy pile design and evaluation, implementing these approaches effectively remains challenging for engineers. This study presents a novel approach based on Load and Resistance Factor Design (LRFD) with First-Order Second-Moment (FOSM) reliability analysis and target reliability ( β T ) for energy pile design. Additionally, three soft computing techniques, namely 1D-CNN, LSTM, and Bi-LSTM, were employed to enhance the design process. To conduct this research, datasets from each model were analyzed using various statistical indices, including R2, RMSE, RMSLE, MAPE, BF, AARD, NSE, U 95 , t-stat, TIC, and PI. The results indicated that the Bi-LSTM model demonstrated superior performance for heating operations, with R2, RMSE, and RMSLE values of 0.975, 0.021, and 0.007 for training and 0.984, 0.019, and 0.006 for testing datasets, respectively. For cooling operations, the LSTM model exhibited the most suitable predictive capabilities, achieving R2, RMSE, and RMSLE values of 0.969, 0.022, and 0.008 for training and 0.982, 0.019, and 0.007 for testing datasets, respectively. Comparative analyses, including rank analysis, Williams plot, accuracy matrix, and Taylor's diagram, were performed to assess the accuracy of the proposed models. The results demonstrated that the Bi-LSTM model for heating and the LSTM model for cooling outperformed other soft computing models within the reliability-based LRFD approach for energy pile design. This research contributes to the advancement of energy pile design methodologies, providing engineers with a more efficient and reliable LRFD-based framework. The successful application of soft computing techniques further enhances the accuracy of predictions for both heating and cooling operations. Overall, the findings of this study hold significant implications for the design and evaluation of energy piles, contributing to sustainable and energy-efficient construction practices. [ABSTRACT FROM AUTHOR]

Over the last few decades, reliability-based design methods have been widely implemented into the foundation design practice. However, several design codes for transmission tower foundations are still based on the allowable stress design (ASD) approach and are yet to adopt the reliability-based approach for design. This paper developed a load and resistance factor design (LRFD) method based on an existing ASD code to design spread foundations of transmission towers under uplift loading in cohesionless soils. In the LRFD development procedures, additional analysis was carried out to check the statistically significant dependency of the model factors (i.e., the ratio between the measured and calculated foundation capacities) on the foundation design parameters. The analysis results showed that there were statistical dependencies between the model factors and the foundation width, which are known as scale effects. By incorporating the identified dependencies, reliability analysis was carried out via Monte Carlo simulations (MCS) by considering the context of transmission tower foundations. From the reliability analysis outputs, it was found that the foundation width had notable effects on the foundation reliability and the calibrated resistance factors. The LRFD format of the existing code was proposed, along with the resistance factors for varying foundation widths and target reliability indices. Finally, a design example was illustrated to compare the design uplift capacities from the existing ASD format and the proposed LRFD format of the design code. Compared to the existing code, the developed LRFD method showed significant improvements in the consistency of the design capacities and the associated reliability levels for a given foundation design. [ABSTRACT FROM AUTHOR]

The increase in freight productivity in Australia is pressuring Australian bridge infrastructure. Bridge assessment is crucial to ensure the safety of bridges to accommodate heavier vehicles. Load distribution factor (LDF) has been widely used for bridge design and evaluation in the preliminary stage, but it is not specified in the Australian standard code. This study aims to develop the LDFs for typical Australian bridges with the most adverse load effects of single- and two-lane loads. Later, the LDFs were compared with the LDF equations in the different standards, including National Association of Australian State Road Authorities (National Association of Australian State Road Authorities, 1976), American Association of Highway and Transportation Officials: Load and Resistance Factor Design (AASHTO (2017), Henry's and modified Henry's methods. It can be concluded that the AASHTO (2017) LDF equations provide very good correlations with typical Australian bridges. It is possible to use the AASHTO LRFD LDF equations for assessing and designing in Australian concrete I-girder and Super-T girder bridges. However, most AASHTO LFRD provides conservative results of LDFs compared with LDFs of Australian bridges. It is recommended that LDFs of Australian bridges should be developed for bridge design and assessment. [ABSTRACT FROM AUTHOR]

Structural reliability theories are used in the calibration of load and resistance factor design (LRFD) in the Canadian Highway Bridge Design Code (CHBDC). The LRFD approach contains certain assumptions about uncertainties in the load and capacity estimation that prevent it from fully exploiting the information gathered during visual inspections. This paper presents a reliability-based framework for analyzing the visual inspection data obtained according to the Ontario structure inspection manual (OSIM). Existing deterioration models are adapted. The Bayesian interference is utilized to estimate the updated structural properties according to the prior information from the bridge maintenance and deterioration models and the new information collected from visual inspections. The criteria set by the CHBDC are used to analyze components and systems reliability. The value of the proposed framework for bridge evaluation and optimizing maintenance is demonstrated through the full implementation of a case-study bridge in the Canadian Province of NB. [ABSTRACT FROM AUTHOR]

The paper describes load and resistance factor design (LRFD) calibration for the resistance factor used in the Stiffness Method internal stability soil failure limit state for geogrid mechanically stabilized earth (MSE) walls. The Stiffness Method was recently adopted in the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications in the US, and will appear in the next edition of the Canadian Highway Bridge Design Code. The paper describes the details of the calibration of the soil failure limit state which is unique to the Stiffness Method. Calibration outcomes include consideration of the concept of level of understanding in the selection of nominal load and resistance values which is unique to LRFD foundation engineering practice in Canada. A practical conclusion from these calculations is that if product line-specific creep test data are available to estimate the reinforcement secant creep stiffness used for design, then a resistance factor of 1.0 is reasonable for US practice. If only minimum average roll value tensile strength data are available, then a value of 0.95 is recommended for US practice. For Canadian practice, the corresponding values for typical level of understanding are 0.90 and 0.85, respectively. [ABSTRACT FROM AUTHOR]

The partial factor method has been widely used in building design and the partial factors to ensure the safety of structures are specified in the adopted codes. The load partial factors in the design expressions have been increased in the lasted code in China, which leads to theoretically increment in reliability and a growth in the consumption of construction materials. However, the influence of load partial factors adjustment on design of building structures arises different points among scholars. Some believe that it has a great impact on the design, some think the influence is small. This makes designers have doubts in the safety of structures and investors are also confused about the cost. In order to illustrate the influence of load partial factor adjustment on safety level and material consumption of RC (Reinforced Concrete) frame structures, reliability analysis and material consumption analysis are performed using First Order Reliability Method (FORM). The approach is carried out according to the load partial factors in Chinese codes of (GB50153-2008) and (GB50068-2018), respectively. Then, the influence of load partial factors adjustment is demonstrated with a case design of RC frame structures with different load partial factors in codes. The results show that the partial factor has a noticeable influence on the reliability index. The adjustment of load partial factors in design leads to an increase of the reliability index, which is about 8–16%. The increase of material consumption used in RC structures is about 0.75–6.29%. And the case indicated that the adjustment of load partial factors mainly result in the increase of reinforcement consumption, while have little effect on the concrete consumption. This study provides an analytical and conclusive insight into the influence of load partial factor adjustment on safety level and material consumption, which is can be applied to a wide range of structures. [ABSTRACT FROM AUTHOR]

In this paper, the ultimate shear capacity of the 3-bolt cold-formed steel clip-angle between the cold-formed steel (CFS) beam and column is evaluated through 54 laboratory tests. A series of experiments were conducted by varying (1) thickness, and (2) aspect ratio (L/D) of clip-angles for different depths (D) and widths (A). The experimental program consists of three phases of tests: (1) Phase-I: direct shear load tests on clip-angle attached to a CFS column through 4.6-grade bolts; (2) Phase-II: CFS column replaced with a hot-rolled steel (HRS) column, since the CFS column experienced bearing failure in Phase-I; and (3) Phase-III: 10.9-grade bolts used instead of 4.6, as the 4.6-grade bolts subjected to bolt shear failure in Phase-II. Failure modes observed in the test specimens are (1) shear local buckling of clip-angle; (2) column bearing failure; (3) bolt shear failure; and (4) tear failure in clip-angle. Design shear equations from the literature, for the bolted clip-angle, were found to be inefficient for the high-grade steel (fy=375 MPa to 550 MPa), and conservative for the commonly available low-grade steel (fy=275 MPa). Hence a new shear strength equation is suggested for the clip-angle from the collated data of the present study and past research work. A comparative study between 2-bolt and 3-bolt clip-angle configurations was conducted to evaluate the increase in shear strength. Reliability studies were conducted, and corresponding resistance and safety factors were suggested for the design shear strength calculation corresponding to load and resistance factor design (LRFD), limit state design (LSD), and allowable strength design (ASD) methods. [ABSTRACT FROM AUTHOR]

To design the foundation system of waterway bridges, Load and Resistance Factor Design guidelines suggest use of deterministic scour depth prediction models. Understanding the inherent bias of deterministic scour depth prediction models will advance the development of reliability index-based foundation design regime. Four bridge scour depth prediction models were assessed in terms of two statistical parameters, termed herein mean absolute percentage error (MAPE), and conservatism, percentage of cases the predicted scour depth exceeded the measured scour depth. Live-bed laboratory and field scour depth databases were used in analyses to quantify model scatter by comparatively assessing the computed scour depth versus measured data. For live-bed laboratory data, values of MAPE ranged from 23.5% to 59.8%, whereas conservatism ranged from 28.4% to 97.8%. For live-bed field data, conservatism varied from 93.3% to 95.1%, while MAPE ranged from 205.6% to 319%. Statistical models were applied to ascertain the biasness of the four deterministic models. Accuracy and conservatism of a given model were consequently adjusted through proposed modification factors. The proposed approach allows for the selection of a suitable modification factor to satisfy a target probability of deceedance or a target conservatism. [ABSTRACT FROM AUTHOR]

The design of shallow foundations typically proceeds by using the load and resistance factor design (LRFD) methodology to avoid various limit states with some probability. This paper looks at the sliding limit state of shallow foundations, and the sliding resistance factors required for the LRFD approach are estimated using reliability analyses of surface strip foundations. Cohesive and frictional soils are separately studied under wind loading conditions. Monte Carlo simulations are used to estimate the sliding failure probability of foundation designs on cohesive soils, and an analytical method is developed for frictional soils. The results indicate the existence of a "worst case" correlation length for cohesive soils, and the sliding resistance factor required to achieve target maximum lifetime failure probabilities is around 0.4–0.65 for moderate soil variability. For frictional soils, the required sliding resistance factor is about 0.5–0.85 for νϕ′ = 0.15. Overall, the sliding resistance factors recommended here agree well with the resistance factors of ϕgu = 0.6 for cohesive soils and ϕgu = 0.8 for frictional soils stipulated by geotechnical LRFD code provisions in Canada. The analyses can be used to estimate the reliability of current designs and can also aid the calibration of geotechnical design codes. [ABSTRACT FROM AUTHOR]

An innovative retrofit system consisting of fiber-reinforced polymers (FRP) and high-performance concrete (HPC) considering the difficulty of the accessibility and installation of FRP on the underside of reinforced concrete (RC) slabs was found to be efficient in the flexural strengthening of existing RC slabs. It is important to note that continuous slabs using the FRP-HPC retrofit systems are less effective in exploiting FRP tensile strength and can cause sudden failure once excessively enhanced flexural strength exceeds shear strength. A design method to ensure ductile failure mode was also proposed for strengthened continuous RC slabs in the previous literature. Thus, it is necessary to optimize retrofit systems in terms of mechanical performance aspects to improve the efficiency of retrofitted slabs in serviceability. This study proposes a design method for optimizing the strength of materials and inducing ductile failure of continuous slab retrofitting FRP-HPC systems. The proposed approach demonstrated its effectiveness for strengthening a continuous RC slab with various FRP-HPC retrofit systems through a case study. The results show that the design factored load in the serviceability limit state does not change appreciably from a decrease in carbon fiber-reinforced polymers (CFRP) of 38%; the design factored load decreased only by 9% and the ultimate failure load by 13% while reducing CFRP by 20% and HPC by 25%. [ABSTRACT FROM AUTHOR]

Context-dependent sensitivities of parameters and reliability-based design (RBD) of rock slopes are the subjects of this paper. The similarities and differences between the design points in RBD and those of partial factor design methods are discussed. It is demonstrated that partial factors provided by the design point of the first-order reliability method (FORM) can provide case-specific insights and guidance to partial factor design methods like Eurocode 7 (EC7) and the load and resistance factor design (LRFD). It is suggested that conducting RBD-via-FORM in tandem with partial factor designs is more illuminating and meaningful than calibration of partial factors of parameters which can be sensitive in one case but insensitive in another case. Three cases are analysed probabilistically with respect to plane sliding in rock slopes with one or more discontinuities. In the first two cases, different deterministic solution procedures are used for the single block and two-block mechanisms, for comparison with stereographic projection method and closed form equation, respectively, prior to extending the cases into RBD. The third case involves a failed slope in a limestone quarry, analysed using FORM in this paper, for comparison with Monte Carlo simulation. Highlights: Alternative deterministic computations obtain same solutions as Goodman's deterministic results for single-block slide and two-block slide. Extend Goodman's deterministic single-block and two-block slides to reliability analysis accounting for input uncertainties. Reliability-based design (RBD) via the first-order reliability method (FORM) provides enlightening information at the FORM design point on parameter sensitivities. RBD-via-FORM automatically reflects context-dependent sensitivities of parameters at the design point of FORM, and can provide insights for Eurocode 7 and LRFD. FORM analysis of a failed slope confirms inadequate reliability. Failure probability from reliability index compares well with Monte Carlo simulation. An efficient procedure for rapid convergence of RBD-via-FORM using the Excel Forecast function. [ABSTRACT FROM AUTHOR]

This paper presents the results of load and resistance factor design (LRFD) calibration of the facing limit states for soil nail walls. The current AASHTO facing load model and a modified model together with the AASHTO facing resistance models for both permanent and temporary facing load cases are considered. The facing design includes flexure, punching shear, and headed-stud tensile limit states. The calibration of resistance factors captures uncertainty in the accuracy of the load and resistance models, uncertainties in the nominal load and resistance values at time of design, and bias dependencies between model bias and nominal values. Resistance factors are calibrated for a range of load factors and target reliability indexes. Example designs for facing limit states demonstrate the implementation of the calibrated resistance factors in a LRFD framework using the current AASHTO and modified load models for the permanent facing load case. The practical values of this study are calibrated load and resistance factors for facing limit states of soil nail walls that are of interest to code writers for future editions of LRFD codes in the United States and Canada. [ABSTRACT FROM AUTHOR]

This paper contains an introduction, probabilistic formulation, and exemplification (1) of system state and utility actions, (2) system state and utility action value analysis and (3) a threshold formulation for a predicted information and action decision analysis. The approaches build upon structural condition assessment and provide a basis for the condition management by maximising the expected utility for information and actions before information acquirement and action implementation. Following the basic distinction of system state and utility actions, strengthening, replacement, repair, load reduction and consequence reduction actions are formulated. With an exemplary study encompassing an expected utility calculation and an action value analysis, it is demonstrated how expected utility optimal physical system changes can be identified before implementation. The threshold formulation for a predicted information and action decision analysis relies on the equality of the decision theoretical posterior action optimality condition. By extending the exemplary predicted action decision analyses with different structural health information (SHI), the threshold formulation is exemplified and the optimal condition management strategies are identified. [ABSTRACT FROM AUTHOR]

Energy piles have been popular globally with functions of both pile foundation and ground source heat pumps. Although several researches have been devoted to the probabilistic design and assessment of energy piles, the corresponding procedures are too complicated for engineers. As a simple variant of the reliability-based design method, the load and resistance factor design (LRFD) approach for the geotechnical design of energy piles is presented in this study. Firstly, the load-transfer model for energy piles is developed to investigate the effect of cyclic thermal loading on the pile settlement. Then, the LRFD procedures based on first-order reliability method and target reliability method are implemented into two different constrained nonlinear optimization problems, respectively. The proposed LRFD model for energy piles is demonstrated through an example pile and a series of parametric analyses. [ABSTRACT FROM AUTHOR]

Reliability-based design (RBD) can overcome some limitations and ambiguities in the partial factor design approach found in Eurocode 7 (EC7) and the load and resistance factor design (LRFD) method used in North America. The aim of this study is to show how RBD via the first-order reliability method (FORM) can complement LRFD and EC7 codes. Three geotechnical engineering examples are used to demonstrate that RBD-via-FORM can provide guidance to the partial factor design approach in situations with load-resistance duality, shear strength parameters with context-dependent sensitivities, parameters not covered in design codes, cross-correlated parameters, and designs aimed at a target reliability or failure probability. Insights from RBD-via-FORM are presented. The differences and similarities between the design points in RBD, partial factor, and LRFD methods are explained. Comparisons are made with Monte Carlo simulations, the mean-value first-order second-moment method, and the Bathurst–Javankhoshdel closed-form reliability index solution which is restricted to simple linear limit state performance functions with lognormally distributed load and resistance terms and bias factors. It is suggested that RBD-via-FORM can be conducted in tandem with EC7 and LRFD methods in order to overcome limitations and ambiguities which sometimes arise using these methods. [ABSTRACT FROM AUTHOR]

Experimental investigations on centrically loaded column bases provide the basis for current punching shear design provisions. However, this symmetric loading condition represents an exception in daily engineering practice since usually load eccentricities occur leading to uneven shear stress distributions along the control perimeter. To account for this effect, design approaches define different factors to either increase the acting shear force or to decrease the punching shear resistance in design. New punching test results of 14 eccentrically loaded and four centrically loaded column bases now allow the evaluation of design approaches depending on different geometric boundary conditions. In this new test series, the load eccentricities were systematically graded to analyze their influence on the punching behavior. Strain measurements in the multiaxial compression zone of the concrete in the column‐footing connection reveal new insights on the punching failure of column bases. As a result, a correlation between tangential concrete strains and the reduction of punching shear strength can be recognized for increasing load eccentricities. The comparison of experimentally determined load increase factors with the design results according to Eurocode 2, Model Code 2010 and the stable version of the next generation of Eurocode 2 reveals optimization potential for deriving more advanced design provisions in the future. [ABSTRACT FROM AUTHOR]

The article presents a study which assessed the effectiveness of a modified live load model in conducting a reliability analysis of typical highway bridges in Manitoba and comply with the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LFRD), the Modified HSS-25. The analysis was conducted in three types of supported structures, including precast prestressed concrete box girder and steel girder.

We consider estimating a factor model for high-dimensional time series that contains structural breaks in the factor loading space at unknown time points. We first study the case when there is one change point in factor loadings, and propose a consistent estimator for the structural break location, whose convergence rate is shown to depend on an interplay between the dimension of the observed time series and the strength of the underlying factor structure. Our results reveal that the asymptotic behavior of the proposed estimator can be asymmetric in the sense that a larger estimation error can occur toward the regime with weaker factor strength. Based on the proposed estimator for the structural break location, we also consider the problem of estimating the factor loading spaces before and after the structural break. We show that the proposed estimators for change-point location and loading spaces are consistent when the numbers of factors are correctly estimated or overestimated. The algorithm for multiple change-point detection is also developed in the paper. Compared with existing results on change-point factor analyses of high-dimensional time series, a distinguished feature of the current paper is that the noise process is not necessarily assumed to be idiosyncratic and as a result we allow the noise process with potentially strong cross-sectional dependence. Another advantage for the proposed method is that it is specifically designed for the changes in the factor loading space and the stationarity assumption is not imposed on either the factor or noise process, while most existing methods for change-point detection of high-dimensional time series with/without a factor structure require the data to be stationary or 'close' to a stationary process between two change points, which is rather restrictive. Numerical experiments including a Monte Carlo simulation and a real data application are presented to illustrate the proposed estimators perform well. • Factor models for high-dimensional time series with structural breaks are studied. • The noise process in the setting can exhibit a strong notion of cross-sectional dependence. • The factor and noise processes are allowed to be non-stationary between change points. • The methods for change-point detection and estimation are proposed. • The asymptotic properties of proposed estimators are investigated. [ABSTRACT FROM AUTHOR]

Under the load and resistance factor design philosophy used in North America, building codes structures are designed using load and resistance factors calibrated to a target reliability level. Despite this, few attempts have been made to calibrate resistance factors for timber connections. A calibration process was carried out for the withdrawal resistance of axially loaded self-tapping screws using a database of test results from across Canada. Two load cases were considered, reflecting load combinations and statistics drawn from the 2015 National Building Code of Canada and from a proposal developed to provide greater consistency in reliability outcomes, and the reliability under each case was determined using the first-order reliability method (FORM). Given the low ductility–brittle nature of withdrawal failures, a resistance factor of φ=0.7 was recommended for a target reliability index of β=4.0. The outcomes will assist in the selection of a resistance factor for self-tapping screws for use in the Canadian timber design standard, CSA O86. [ABSTRACT FROM AUTHOR]

A simplified calculation method is proposed for determining the peak dynamic windage yaw angle φ ^ of electricity transmission line (TL) tower suspension insulator strings (SISs). According to the rigid-body rule, the geometric stiffness matrix in the calculation of the windage yaw angle φ of SISs is dominated by the average wind loads, while the fluctuating wind loads are the dominant factor in the elastic stiffness. With the average wind state of conductors as the initial calculation condition, the load-response-correlation (LRC) method can be used to determine the fluctuating windage yaw angle φ d and the corresponding equivalent static wind loads (ESWLs). Then, the improved rigid straight rod model, which uses the actual length of conductors rather than the projected length, was used to determine the average windage yaw angle φ ¯. Through the linear superposition of the horizontal increments of φ ¯ and φ ^ d (the peak value of φ d ), the formulae to calculate the φ ^ of SISs were derived. Additionally, the formulae for the dynamic wind load factor, β c , which is a key factor in designing wind loads for φ , were derived according to the principle of ESWLs, rather than being empirically determined by the Chinese code. Thus, the calculation model regarding the loads and response for the φ of SISs was established, and an actual TL was used to verify the established calculation model. Afterward, the influence of the different engineering design parameters on φ and its β c were analyzed. The parameter analyses show that the wind speed, span, and ground roughness influence the magnitudes of φ ^ and β c , however, the height difference between the two suspension points of the conductors, the nominal height, and the sag-to-span ratio may be neglected in the approximate calculation. Our method offers a new solution to TL design when there are large deformations and small strains. [ABSTRACT FROM AUTHOR]

Load and resistance factor design (LRFD) for serviceability limit state (SLS) of laterally loaded drilled shafts was explored for transmission line structures in sand, and the SLS resistance factor (RF) was proposed. Statistical characteristics of various load components, including transverse tension load (TTL), wind-on-structure load (WSL), and wind-on-conductor load (WCL), were considered and assessed. A database was established and adopted to calibrate RF for SLS of laterally loaded drilled shafts in sands. The hyperbolic model was introduced to quantify uncertainties in the lateral load–displacement curves for drilled shafts and adopted to determine the allowable load capacity. A Monte Carlo simulation was performed to calibrate RF for SLS. The effects of target reliability index (βT), allowable displacement (ya), ice thickness on conductor (Iz), and various load ratios were all considered in the RF calibration. The values of RF for SLS varied from 0.19 to 0.94 for βT in the range of 1.5–3.5. Equivalent factors of safety (FSeq) were obtained for the proposed RFs to evaluate and compare the safety margin of SLS to that of current design practice. [ABSTRACT FROM AUTHOR]

This article reviews the existing design philosophies of structural elements made of different structural materials in general and bamboo materials in specific. The theories behind design practice would be the main cornerstone for articulating why and how we employ a single philosophy. The demand for using verified theories or philosophies will facilitate the drawing of sound models. The detailed theoretical basis and methods that include the fundamental one are studied through extensive literature reviews in an organized way, and a critical synthesis has been made upon the basic parameters identified. Establishing a sound philosophy to address the existing behavior of materials and loads takes quite a time. Philosophies like allowable stress design, load factor design, and limit state design are the classical ones, while capacity-based, performance-based, and risk-based are the emerging ones for structural element design. The key characteristics for addressing the possible factors for developing a philosophy, whether classical or emerging, are valuable to seek out. The paper identifies the key parameters to develop a design philosophy using a Delphi survey from selected scientists. The key parameters found are material behavior, load behavior, displacement, failure modes, functionality, and method of construction. The identified key parameters need to be incorporated while developing a sound structural design philosophy. It is found that there is a significant relationship between material properties and design philosophy available when the force-based design approach is preferred, but if the functional-based and displacement-based approaches are used, there is no significant relationship between material properties and design philosophy. [ABSTRACT FROM AUTHOR]

• A physics-informed artificial neural network is proposed for the buckling design of axially compressed cylindrical shells. • Physical knowledge derived from the local reduced stiffness method and elastic buckling theory is incorporated into an artificial neural network model. • Physics-informed feature and loss function could improve the predictive accuracy of artificial neural network. • The physics-informed model could predict moderately conservative buckling loads with a design factor of 1.25. A physics-informed artificial neural network (ANN) is developed for the buckling design of cylindrical shells under axial compression, and two strategies are applied to incorporate physical knowledge into the ANN model. One strategy is to introduce physics-informed features derived from the local reduced stiffness method (LRSM) as additional input features. The other strategy is to incorporate physical constraints based on elastic buckling theory into the loss function of ANN. The accuracy of the proposed model is verified using a buckling dataset of metal and non-metal cylindrical shells. Results demonstrate that the proposed physics-informed ANN model with four hidden layers achieves better predictive performance than pure data-driven random forest (RF), support vector machine (SVM) and ANN. Furthermore, the physics-informed model could predict moderately conservative buckling loads with a design factor of 1.25. [ABSTRACT FROM AUTHOR]

Reliability-based design concepts have been widely adopted in structural engineering but remain less prevalent in geotechnical practice due to the challenges of characterising ground uncertainties. To facilitate the unification of structural and geotechnical designs in complex engineering systems, we focus on square shallow foundations as crucial elements. Before a complete transition to load and resistance factor design, understanding the reliability of foundations designed using traditional factors of safety is essential. This paper presents a simplified analytical method for evaluating the probability of failure of square shallow foundations on 3D cohesive soils, utilising local average theory. The approach efficiently computes local averages and covariances of soil properties without the need for time-consuming 3D finite element computations. Verified against random finite element analysis, the method accurately determines required factors of safety for bearing capacity designs. Site-specific parameters, including sample location, shear strength coefficient of variation, and spatial variability fluctuation scale, influence the derived factors of safety. We advocate a pragmatic approach that calibrates traditional factor of safety methods with rigorous reliability theories, easing the transition to reliability-based design for practicing engineers. Moreover, the determined factors of safety can aid in establishing appropriate resistance factors by considering suitable load factors. [ABSTRACT FROM AUTHOR]

The partial safety factor method commonly necessitates a set of multiplying factors (MFs) to modify the basic variables; hence, when multiple variables are included, it is complicated for design practice. Conversely, the load and resistance factor design (LRFD) format is more practical since it utilizes fewer factors to adjust loads and resistance. This study carries out a comparative study of the two semi-probabilistic design formats and four calibration methods to determine the more suitable design approach and establish associated factors for sliding stability designs of caisson breakwaters under wave and seismic conditions. To fulfill the aforementioned purposes, 12 perforated caisson breakwaters are first selected; thereafter, four calibration methods, which include a closed-form solution and three scenarios based on Monte Carlo simulation (MCS), are executed to determine individual MFs for each case. The final single set of MFs for design practice is calibrated via an optimization process. The present study shows that the two design formats can provide similar solutions. Hence, the LRFD-based concept is recommended to be applied owing to its easier implementation in code calibrations and design practices. Moreover, the performance of the shifting-technique-MCS-based calibration (the simplest simulation) is thoroughly investigated, and it is then found that this approach must be used with care if the target safety considerably varies from the initial safety level. In the present work, an efficient and accurate approximation method to specify the final MFs set is proposed because the optimization-based calibrations to determine the final set of MFs are time-consuming and expensive to evaluate. • Performances of LRFD and PSM were examined and compared. • Similar LRFs were calibrated, although non-unique solutions occurred in DMCS. • Drawbacks of SMCS were pointed out, and SMCS is not suggested in practice. • TDMCS was reported as the most suitable method to calibrate LRFs. • A facile method avoiding optimization problems was proposed to assess final LRFs. [ABSTRACT FROM AUTHOR]

Modern structural design standards are based on the Limit State Design (LSD) philosophy, also known as Load and Resistance Factor Design (LRFD), which involves the use of resistance functions with accompanying safety factors that are based on a statistical evaluation of relevant experimental data, carried out within the framework of a probabilistic reliability theory. This paper presents the derivation of material factors for the yield strength and ultimate tensile strength of austenitic, duplex and ferritic stainless steels, and their associated coefficients of variation (COV) for use in evaluating the safety factors for the European design code EN 1993-1-4 and the American design codes Specification for Structural Stainless Steel Buildings (ANSI/AISC 370–21) and Specification for the Design of Cold-Formed Stainless Steel Structural Members (ASCE/SEI 8–22). Separate material factors and associated COV values are required for the U.S. and European design codes due to the different minimum specified strength values that are given in the respective product standards. The material factors were derived by analysing a large amount of material data provided by different stainless steel producers, which encompassed a wide range of stainless steels and material thicknesses. • Statistical analysis of the strength variability of stainless steels is presented. • Data from over 250,000 tensile coupons was collected and analysed. • Existing European material factors were found to be optimistic. • Stainless steel material factors are derived for European and U.S. standards. [ABSTRACT FROM AUTHOR]

Current design practice in the United States allows engineers to use either Allowable Strength Design (ASD) or Load and Resistance Factor Design (LRFD) method, under the assumption that both methods provide similar levels of economy (available design strengths) and safety (probabilities of failure and reliability indices) regardless of the design conditions. Recent studies have demonstrated that significant differences in economy can arise between ASD- and LRFD-based designs subjected to combinations of gravity and wind loads, suggesting inconsistencies between the safety levels. This study investigates the safety levels provided by the ASD and LRFD methods for such design cases. The safety levels were estimated using a formal reliability analysis with consideration of geometrically non-linear second-order effects. The reliability analysis was performed using Monte Carlo simulations with appropriate probability distributions for the random variables associated with both resistance and loads. The findings of this study indicate that generally accepted uniformity of reliabilities achieved by the ASD and LRFD methods does not hold for design cases governed by wind loads. The safety levels achieved by using the ASD method are less consistent than those achieved by using the LRFD method. The use of the ASD method generally entails the acceptance of failure risks many times greater than for those of the LRFD method, and target safety levels lower than those stipulated by the ASCE 7 Standard. These results highlight the need for a reevaluation of the current design practices to ensure that the required target levels of structural safety are consistently met. • This study investigates the safety levels (probabilities of failure and reliability indices) achieved by the ASD and LRFD methods for designs subjected to combinations of gravity and wind loads. • The safety levels were estimated using a formal reliability analysis, consistent with methods detailed in the ASCE 7 Standard, and with consideration of geometrically non-linear second-order effects. The reliability analysis was performed using Monte Carlo simulation with appropriate probability distributions for the random variables associated with both resistance and loads. • The findings of this study indicate that generally accepted uniformity of reliabilities achieved by the ASD and LRFD methods does not hold for design cases governed by wind loads. • The safety levels achieved by using the ASD method are less consistent than those achieved by using the LRFD method. The use of the ASD method generally entails the acceptance of failure risks many times greater than for those of the LRFD method, and target safety levels lower than those stipulated by the ASCE 7 Standard for many design cases. • The results of this study highlight the need for a reevaluation of the current design practices to ensure that the required target levels of structural safety are consistently met. [ABSTRACT FROM AUTHOR]

Partially or fully restrained steel moment connections are essential constituents of lateral force resisting moment frames. The constituents of the moment connection system – bolts, welds, plates and angles – are sized using their individual force demands by a limit state element-based load and resistance factor design procedure. The system reliability of the connection as a whole, which must be commensurate with reliabilities of adjoining frame components, has not been adequately investigated in the literature. This paper presents a methodology to determine the system reliability of commonly used steel moment connections that have been designed according to current element based procedures. A general expression is derived for a system factor that modifies element resistance factors to meet a specified system reliability target, as a function of the element's relative importance within the system, and associated uncertainties. Uncertainties in element capacities (including their mutual dependence) and system demands are considered. The approach can be used to rationalize element design equations to achieve system reliability targets for the connection system. A detailed numerical example and a set of parametric studies on a partially restrained moment connection with angle supports at top and bottom beam flanges are presented. The results suggest the existence of beneficial system effects in current AISC provisions for the design of partially restrained moment connections. • A novel system reliability design approach for steel connections is presented. • System to element reliability surfaces are constructed using nonlinear analysis. • An analytical expression for system design factor is derived. • A detailed example demonstrating potential application in design is provided. • Conservatism in current AISC design approaches results in system factor¿1.0. [ABSTRACT FROM AUTHOR]

ASCE 7, Minimum Design Loads for Buildings and Other Structures, provides load combinations for both Load and Resistance Factor Design (LRFD) and for Allowable Stress Design (ASD), defining the required strength of structural members and connections. Similarly, the AISC Specification for Structural Steel Buildings provides resistance factors for LRFD and safety factors for ASD to be applied to the nominal strength for each limit state, permitting design using either method in conjunction with the corresponding load combinations in ASCE 7. Previous publications have demonstrated that similar designs (with similar levels of reliability) result from the application of LRFD and ASD for cases in which the governing load combination has live load as the principal load. This study presents comparison of ASD and LRFD demands, and corresponding reliability indices, from ASCE 7 lateral load combinations, determined with different proportions of dead, live, wind, and seismic load effects and a range of levels of second-order effects. The findings indicate that the generally accepted uniformity between the two design methods established for gravity load combinations does not always extend to lateral load combinations. For a range of conditions, design using ASD load combinations provides significantly lower reliability than using LRFD and does not meet the ASCE 7 reliability target. • ASD and LRFD design methods can result in significant differences in required strength for lateral-load combinations. • Differences in required strength are influenced by load ratios and second-order effects. • Differences in required strength result in significant differences in reliability for wind loading. • LRFD provides more consistent reliability across a range of conditions than ASD, with reliability near the target. • ASD results in a wide range of reliability, including both the greatest overdesign and the greatest underdesign with respect to target reliability. [ABSTRACT FROM AUTHOR]

The paper demonstrates load and resistance factor design (LRFD) calibration for tensile strength and pullout strength limit states for steel strip mechanically stabilized earth (MSE) walls using a reliability theory-based approach. The analyses adopt load models found in current North American LRFD specifications in combination with a coupled mechanical-corrosion model for the reinforcement tensile strength and pullout models found in design guidelines and in the research literature. Resistance factors for prescribed load factors and different load and resistance model combinations are compiled in tables. The limitations of the LRFD approach to generate resistance factors that are judged to be acceptable based on current practice are demonstrated. The challenges to generate consistent design outcomes with the same margin of safety expressed probabilistically are identified, and the link to reliability-based design is described. Example designs are provided to show the impact on steel reinforcement quantities and length when using different models in combination with proposed and current specified load and resistance factors. The calibration outcomes will be of value to code writers in Canada and the US for MSE wall design sections in the next editions of national geotechnical foundation LRFD codes. [ABSTRACT FROM AUTHOR]

Pile foundations are one of the significant marine substructure systems for a variety of offshore and onshore facilities. Thus, optimum and reliable design during their lifetime and under inherent uncertainties is noteworthy. Among various methods for predicting axial pile bearing capacity, cone penetration test (CPT)-based methods enhance geotechnical design to a more satisfying level due to continuous and reliable CPT records and their suitable performance in offshore environments. This article aims to reveal the importance of CPT and pile databases, especially in deltaic deposits. A new relevant CPT and pile data-based approach is introduced by assessing a few elaborated works on typical CPT and pile case studies. The proposed procedure assists in comparing the characteristics and conditions of a given pile with similar database cases through screening and, consequently, deciding on the design methods' priority. It is depicted that superior methods result in a more reliable design and higher resistance factors and efficiency ratios in load and resistance factor design (LRFD). Accordingly, it is engaged with lowered safety factors in the allowable stress design (ASD) approach. Eventually, upon various assessment criteria, the optimum site-specific methods are proposed leading to a performance-based design that can be realized in geotechnical practice. [ABSTRACT FROM AUTHOR]

In this study, the resistance factors (RF) in the load and resistance factor design (LRFD) for the drilled-shaft foundation of transmission line structures subjected to lateral loads were investigated. Various load test results were collected to establish a database and used in the reliability analysis. The first-order reliability method (FORM) was implemented to calibrate RF for the Broms, Brinch-Hansen, and Prasad and Chari methods. Loads for transmission line structures were categorized and characterized statistically for calibrating RF. Uncertainties of the transverse tension load (TTL), wind-on-structure load (WLs), and wind-on-ice-coated conductor load (WLc), all dominant in transmission line structures, were evaluated. RF varied largely with nominal load ratios of WLs/TTL and WLc/TTL , which should be considered for the selection of RF in the design to maintain a consistent safety margin. Increases in nominal WLs and WLc induced higher RF while increasing nominal TTL yielded lower RF. The higher RF values obtained in this study were due to the low bias factors of wind-induced loads and the large load factors of the tension and wind loads. The equivalent factor of safety (FSeq) was evaluated and analyzed for the proposed RF s. [ABSTRACT FROM AUTHOR]

6.Databaseofloaddata Miyata and Bathurst (2019) developed a database of 113 measured steel grid loads (T max) from 11 instrumented steel grid walls constructed with cohesive-frictional soils and purely frictional soils. Reliability-based design and analysis for internal limit states of steel grid-reinforced mechanically stabilized earth walls. Thegeneralapproachdescribedin thispaperisanimportantcontributiontonext-generationanalysis and design using modern concepts of RBD for internal stability design of both steel and polymeric soil-reinforced MSE walls and is thus in alignment with the international movement towards RBD for geotechnical structures (e.g., Low and Phoon 2015;Phoon2017;PhoonandChing2015;ISSMGE2017). Allen et al. (2001, 2004) quantified the level of accuracy of the Simplified Method for steel MSE walls using bias statistics deduced from a large number of instrumented walls. 1.Introduction This paper is focused on reliability-based design (RBD) and analysis for tensile strength and pullout limit states of steel grid-reinforced mechanically stabilized earth (MSE) walls constructed with frictional soils and subjected to typical operational conditions. [Extracted from the article]

A total of 105 cross-tension tests were conducted to investigate the strength and behavior of power-actuated fastener (PAF) connections under quasi-static monotonic tensile loading. Three types of PAF were used to join sheets with thicknesses ranging from 0.75 to 4.00 mm to thicker plates with thicknesses ranging from 3.00 to 20.0 mm. All of the steel materials were high-strength cold-formed steel, except for the 20-mm-thick steel, which was hot-rolled steel. The studied parameters were the type and diameter of the fasteners and the thicknesses of the top and base steel materials. The majority of the specimens failed by pull-out failure, although some thinner sheets failed by transverse fracture of the top sheet. The test results reveal that PAF connections exhibit a high tensile capacity as long as a sufficient embedment length is provided. A model is proposed to evaluate the pull-out strength of PAF connections based on the base material strength and the average embedded diameter and embedment length of the fastener. The proposed model produces a mean of test-to-prediction ratio equal to 1.02 with a coefficient of variation ranging from 0.12 to 0.16. Reliability analyses were carried out and resulted in a resistance factor of 0.56–0.69 for Load and Resistance Factor Design. [ABSTRACT FROM AUTHOR]

Load tests of drilled shafts are often performed using Osterberg cell (O-cell) testing, a popular load test method for drilled shafts, which measures both side and tip resistance. However, it is common that only one of the resistance components can be fully mobilized. Therefore, extrapolation of the partially mobilized resistance is often required to determine the total resistance or the equivalent top-down curve. The extrapolation tends to introduce errors to the constructed total resistance values, which subsequently affect the calibrated resistance factors required for the LRFD design of drilled shafts. In this study, eight O-cell tests of drilled shafts with total measured resistances close to the failure criteria defined by FHWA, 5% of the shaft diameter (B), were collected among 64 drilled shaft load tests from Louisiana and Mississippi. For each of the eight cases, extrapolation was performed on both tip and side movement curves for the construction of the equivalent top-down load-settlement (ELT) curves. Data points from the measured side or tip movement curve were removed systematically to create a total of 80 cases with partially mobilized movement curves, and extrapolation exercises were performed on each fabricated case to obtain its equivalent top-down curve. The error of bias for each fabricated case was determined for statistical analyses. Multiple linear regression analysis was performed on the bias errors to model the bias errors caused by extrapolation. Calibrated resistance factors were determined and compared between the original database and fabricated database needing extrapolation. A correction method is proposed, based on a linear regression relationship, to estimate and minimize the extrapolation error of bias for less mobilized databases. [ABSTRACT FROM AUTHOR]

Fixed offshore platforms in the Gulf of Mexico (GoM) are traditionally designed following the working stress design (WSD) format, that is, the factor of safety approach. In 1993, the first reliability-based design standard for offshore platforms using the Load and Resistance Factor Design (LRFD) format was published by the American Petroleum Institute (API) called Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platforms—Load and Resistance Factor Design, which is commonly abbreviated as API RP 2A-LRFD 1st edition. API RP 2A-LRFD 1st edition has had a significant influence in developing the LRFD format of the ISO for fixed offshore structures (i.e., ISO 19902), but it was not commonly used in the United States, and it was withdrawn in 2012 due to a lack of maintenance. The API RP 2A-LRFD format was reintroduced in 2014 as a draft 2nd edition. This study was carried out in the context of the plan to prepare the API RP 2A-LRFD 2nd edition under the effort to align and merge the API and ISO standards as a single global standard. The objectives of this study are to assess the fixed offshore platform component reliability with the accumulated experience in the last several decades, and to evaluate the suitability of the load and resistance factors in API RP 2A-LRFD 1st edition for the 2nd edition of API LRFD given the updated metocean characteristics after Hurricane Katrina in the GoM. The key findings of this study are that the LRFD format with the load and resistance factors from API RP2A-LRFD 1st edition gives slightly higher reliability levels for component checks than the WSD format, but lower reliability level with the updated new metocean criteria comparing to the criteria in the 1980s. A list of recommendations on the load and resistance factors was provided to facilitate the preparation for the API RP2A-LRFD 2nd edition. [ABSTRACT FROM AUTHOR]

• Moment live load distribution factor (LLDF) predictions of AASHTO LRFD BDS including skew correction factors were, in general, conservative as compared to field measurements. AASHTO shear LLDFs were very conservative for all girders when compared to field measurements. • Analysis results showed that seasonal temperature changes were sufficient to create measurable superstructure in-plane rotations. Skewed superstructures were observed to rotate towards obtuse and acute corners for negative and positive temperature changes, respectively. • Increasing skew angles increased displacements at bearings in the bridge transverse direction. • For all cases, transverse bearing displacements were markedly greater than longitudinal ones. This has a special significance in typical bearing design where transverse bearing displacements are usually ignored. • Using a mix of fixed and expansion bearings over the same pier substantially reduces transverse bearing displacements and racking under temperature changes. High skew in bridges alters live load distribution and creates performance issues such as deck cracking, superstructure in-plane (horizontal) displacements and bearing distress. In-plane superstructure displacements, also called racking, are particularly important as they cause misalignments of superstructure and approach slabs, stress bearings and expansion joints. This study had two objectives: to evaluate live load distribution in skewed bridges and to understand how skew influences in-plane superstructure displacements. The effect of bridge design details on live load distribution and in-plane superstructure displacements was assessed through parametric studies on highly skewed bridges. A three-span, steel girder-concrete deck bridge with a 47-degree skew was load tested. Load test results were employed to validate finite element analyses that were used to understand the impact of varying skew angle, bridge features and bearing fixity on live load distribution and in-plane superstructure displacements. The ability of the American Association of Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications (AASHTO LRFD BDS) to accurately capture live load distribution for steel girder bridges was evaluated. Field test results, consisting of girder bending and vertical shear strains measured through strain gages strategically located on one of the exterior spans, and parametric studies showed that AASHTO LRFD BDS predicted shear and moment distribution very conservatively and closely, respectively. Seasonal temperature changes were sufficient to create in-plane (horizontal) superstructure displacements. These displacements caused the superstructure to rotate towards obtuse and acute corners for negative and positive temperature changes, respectively. Larger skew angles led to greater transverse (i.e., perpendicular to bridge longitudinal axis) displacements at girder bearings. Longitudinal (i.e., parallel to bridge longitudinal axis) displacements were consistently smaller than transverse displacements and were not affected by skew. Mixed bearing fixity arrangements, with both fixed and expansion bearings over the same pier, limited superstructure transverse in-plane displacements. [ABSTRACT FROM AUTHOR]

Possessing a more complicated mechanism and catastrophic brittle collapse mode, it is necessary to investigate the reliability level of design guidelines for concrete structures shear strengthened with fiber reinforced polymer (FRP). In this paper, six guidelines have been appraised based on the philosophy of load and resistance factor design approach. First, the model error of shear capacity prediction was identified. Subsequently, the reliability index was estimated, followed by the calibration of FRP design factors and a comparison of the design economy. The results show that: (1) For U-jacketing and fully wrapping, the Chinese guideline is the most accurate. For side bonding, both Chinese and American guidelines show a satisfying prediction. (2) The reliability index for U-jacketing is generally larger than that for side bonding and smaller than fully wrapping. (3) The Australian guideline provides the largest reliability indexes for U-jacketing and side bonding, while the British guideline provides the largest reliability indexes for fully wrapping. (4) Besides the reliability level, the design economy also relies on the sensitivity of β to design factors. For U-jacketing, CIDAR shows the best economy, followed by CSA and fib. For fully wrapping, TR shows the best economy, followed by CIDAR and ACI for β T < 3.5. [ABSTRACT FROM AUTHOR]

The design of transmission lines is based on the Load and Resistance Factor Design approach, considering that their collapse limit state is governed by climatic actions (wind and ice). Even so, accident reports indicate the regular observation of moderate to severe damage of towers after strong ground motions, affecting the structure's capacity to withstand future load events. Therefore, integrating the concepts of Performance-Based and Multi-Hazard Design, successfully applied to buildings and still embryonic to transmission lines, seems to be promising. With such performance-based multi-hazard approaches, intermediate performances can be evaluated even when they are controlled by a non-dominant hazard. Hence, the present paper aims at performing an original multi-hazard assessment of a Chilean 230kV transmission line segment. For this purpose, direct geometric and material nonlinear time history analysis, using a finite element suitable for eccentrically loaded angle profiles (L-shaped cross-sections), is employed to construct the fragility curves. In addition, uncertainties in loads and material properties are accounted for to address the transmission line system failure probability. In the existing literature, fragility analysis has been performed through pushover approaches, whereas reliability has been assessed for a single structure rather than for the transmission line system, as recommended by line codes. Contrary to design practice, the results show that seismic loads control all limit states in TLs located from central to northern Chile. Numerical results presented in this paper are based on 5000 h of total computation time. • Seismic + wind multi-hazard assessment of full transmission line segment. • Performance-based approach considering multi-hazard curves. • Direct geometric and material nonlinear time history analysis performed. • Several locations in Chile considered; for some locations. • Collapse LS controlled by wind, but serviceability and damage LS controlled by seismic actions. [ABSTRACT FROM AUTHOR]

• An algorithm is proposed to determine an optimal site investigation plan (OSIP) that will reduce the ground and geological (geomaterial) uncertainties. • Geomaterial uncertainties are explicitly considered in the design of H-piles driven into weathered shale. • The effects of using OSIP and geostatistical simulation on the predicted resistance and reliability of bridge pile foundations are quantified. • Cost-benefit and break-even analyses are conducted to determine the cost-effectiveness of OSIP. Site investigation (SI) provides relevant subsurface information for designing piles driven into soft rocks or intermediate geomaterials (IGMs) such as shale. However, uncertainties in geological and ground (geomaterial) conditions pose challenges to accurately predicting pile resistance and ensuring design reliability. This study used multinomial categorical prediction (MCP) and conditional simulation on a random field to develop an optimal SI plan (OSIP). The OSIP aims to minimize geomaterial uncertainties, improve design efficiency, and enhance the economic benefits of pile foundations. The proposed method integrates OSIP with static analysis (SA) methods. This integration enhances the calibrated resistance factor from the load and resistance factor design (LRFD) by improving the quality of geomaterial information used in pile resistance prediction. The effectiveness of the proposed method is demonstrated using a database consisting of 22 steel end-bearing H-piles that are driven into weathered shales and load tested in Kansas, Iowa, and Wyoming. By incorporating OSIP into pile design, the prediction error of end-bearing resistance is decreased by 25.6%, and the LRFD resistance factor for redundant piles is increased by 20%. Furthermore, a cost-benefit analysis of the pile design reveals an average saving of approximately $39,410 per foundation. Break-even analysis further supports OSIP as a cost-effective SI plan option for enhancing pile design. [ABSTRACT FROM AUTHOR]

• A novel strengthened screw connection by wrapping with CFRP sheets was suggested. • Failure modes and Shear performance like shear strength, deformation capacity and energy dissipation capacity, etc. improved significantly. • The shear toughness of connections increased by more than 1.9 times according to the proposed evaluation method. • Design formulae for the shear strength of the CFRP-strengthened connections were recommended based on LRFD and ASD methods in AISI S100. Cracking damage of the sheathing wallboards in screw connections is the typical failure mode of cold formed steel (CFS) structures under seismic effects, which limits the shear capacity and weakens the hysteretic performance of CFS structures. To improve the shear performance of CFS-sheathing screw connections, a novel screw connection with carbon fiber reinforced polymer (CFRP) reinforcement is proposed in this paper. Cyclic tests were conducted on a total of 26 sets of screw connections with different configurations and wall sheathings, and the effects on the failure modes and shear performance of the connections with and without CFRP reinforcement were investigated. The strengthening effects of the sheathing material, panel thickness and end distance on the shear properties of the connections were discussed. The results indicated that (1) except for specimens with 15 mm end distance, CFRP reinforcement can effectively avoid brittle cracking failure of the connections, and the failure mode tended to ductile failure of the bearing and pull-through damage. (2) in addition to the stiffness, the shear strength, deformation capacity, ductility and energy dissipation capacity of CFRP-strengthened connections are significantly enhanced. The effect of CFRP on the shear performance improvement of connections sheathed with gypsum board (GWB) and magnesium glass board (MgO) is greater than that of oriented strand board (OSB), and the strengthening effect is not significantly influenced by the board thickness. A toughness evaluation method for CFRP-strengthened connections was proposed, and the design formulae for the shear strength of the CFRP-strengthened screw connections were recommended based on the load resistance factor design (LRFD) method and allowable strength design (ASD) method. [ABSTRACT FROM AUTHOR]

Improving soil mechanical properties using reinforcement inclusions has become of major interest to many researchers. Accordingly, several numerical, analytical, and experimental studies have been conducted to explore the improvement of soil's mechanical properties under shallow foundations. However, a comprehensive Reinforced Soil Foundations (RSF) design framework has not been established. This paper introduces a novel design framework for RSF based on the Load and Resistance Factor Design (LRFD) approach. Resistance factors for improved bearing capacity are computed using the First Order Reliability Method (FORM) for strip and square footings resting on loose sandy soil. A spreadsheet-based model is developed to compute the resistance factors at a targeted reliability index (β T) equal to 3 for ASCE-7 2000, AASHTO 1998, and EC7 (DA2) load factors. The resistance factors developed using ASCE-7 load factors ranged from 0.2 to 0.55 and 0.27 to 0.7 for a geogrid tensile strength of 45 kN/m and 160 kN/m, respectively. Load factors of different established design codes had a significant effect on the developed resistance factors. Soils with high frictional angles and embedment ratios resulted in conservative resistance factors. Moreover, the computed resistance factors for square footings were slightly higher in reinforced cases and lower for unreinforced cases than in strip footings. • Introducing a novel design framework for RSF based on LRFD approach. • Computing resistance factors for improved bearing capacity using FORM. • ASCE-7 2000, AASHTO 1998, and EC7 (DA2) load factors are considered. [ABSTRACT FROM AUTHOR]

The objective of this research is to demonstrate that parts of decommissioned wind turbine blades can be repurposed for infrastructure applications for a sustainable future of the wind power industry. The purpose of this paper was to develop a methodology to conduct detailed structural engineering design of composite material parts extracted from wind turbine blades. A large section extracted from a 100-m long blade was repurposed as a roof for a small (approximately 40 m2) single-story masonry house. Geometric and material properties were taken from the blade design documents. A three-dimensional graphical model was created from the exterior surface and material layups. The roof was designed using the load and resistance factor design method familiar to civil engineers. Analysis of stresses and defections was conducted using hand calculations and the finite element method. The results of the analyses showed that the roof is within code mandated stress and deflection limits. The methodology developed could be applied to other wind blade repurposing concepts. [ABSTRACT FROM AUTHOR]

This paper compiles two expanded databases—NUS/SpreadFound/919 and NUS/RockFound/270—to evaluate the calculation methods of foundation capacity, where the number is the number of load tests collated. The mean (bias) and coefficient of variation (COV) (dispersion) of the model factor, defined as a ratio of measured-to-calculated capacity, are computed. With the statistics of a ratio of calculated-to-observed foundation settlement reported in literature, design methods for foundation capacity and settlement are classified according to their ability to match measured values. Such a statistical-based classification provides the designer with a sense of the accuracy of a capacity or settlement model. For the 298 case records in NUS/SpreadFound/919, the uncertainty exhibited by the load-movement curves over their full range of movements is captured by two parameters in a hyperbolic fitting of measured data. Copula analysis is adopted to evaluate the observed correlation structure between the hyperbolic parameters. Finally, the model statistics are applied to calibrate the resistance factors in load and resistance factor design of spread foundations at ultimate and serviceability limit states. [ABSTRACT FROM AUTHOR]