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Continued development of wind farms near populated areas has led to rising concerns about the potential risk posed to general aviation aircraft when flying through wind turbine wakes. There is an absence of experimental flight test data available with which to assess this potential risk. This paper presents the results of an instrumented flight experiment in which a general aviation aircraft was flown through the wake of a utilityscale wind turbine at an operating wind farm. Wake passes were flown at different downwind distances from the turbine, and data were collected on the orientation disturbances, altitude and speed deviations, and acceleration loads experienced by the aircraft. Videos and pilot statements were also collected, providing qualitative information about the disturbances encountered in the wake. Results show that flight disturbances were small in all cases, with no difference observed between flight data inside and outside the wake at distances greater than six rotor diameters from the turbine. At distances closer than six rotor diameters, small load factor and orientation disturbances were noted but were commensurate with those experienced in light or moderate atmospheric turbulence. Overall, the loads and disturbances experienced were far smaller than those that would risk causing loss of control or structural damage. [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymer (FRP) reinforcement has been employed as an alternative to conventional steel reinforcement in concrete structures, which is attributed to its excellent strength and corrosion resistance. However, one drawback is that FRP reinforcements are brittle and affect the ductility of concrete structures. One of the recent effective techniques proposed to overcome ductility issues is the compression yielding (CY) concept. The CY mechanism allows the structure to fail differently than the conventional FRP-reinforced concrete structure. Thus, the existing design recommendations as per the current codes for FRP-reinforced concrete structures are not appropriate. Hence, reliability studies are crucial for the development of a functional CY beam design in order to emphasise the structure's lifetime performance and to guarantee safety requirements. In this study, a reliability-based design approach is developed for a compression-yielded FRP-reinforced concrete beam (CY beam) using load and resistance factor design (LRFD). Firstly, the flexural failure modes of CY beams are discussed. The uncertainties involved in the development of the probabilistic model for the CY beam are defined. A case study is consequently conducted for a CY beam with random variables that are associated with the statistical characteristics of material properties and load. The reliability analysis method employed in this research is the Hasofer–Lind method. The results suggest the importance of choosing appropriate design variables and stochastic parameters for CY blocks that contribute to a higher level of reliability. The reliability index and resistance factors of a CY beam are then evaluated using the Monte Carlo Simulation computational method. The reliability index value of 3.336 is obtained from the simulation, which indicates that the CY beam demonstrates ductile behaviour. The results not only demonstrate ductile behaviour but also contribute to a possible reduction in material costs and a substantial safety margin. When compared to conventional FRP-reinforced concrete beams, for different load ratios, CY beams showed higher resistance and better reliability levels. [ABSTRACT FROM AUTHOR]

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]

The Wave Equation Analysis of Pile Driving (WEAP) has been widely used to determine drivability, predict static resistance, and assure the integrity of piles in soils. Assigning static and dynamic properties of Soil-based Intermediate Geomaterials (S-IGMs) remains a challenge in WEAP, partly attributed to IGMs that act as transition geomaterials between soil and hard rock. Furthermore, reliable static analysis methods for unit resistance predictions are rarely available for driven piles in S-IGMs in the default WEAP method. To alleviate these challenges, this study presents improved WEAP methods for steel piles driven in S-IGMs, including proposed damping parameters and Load and Resistance Factor Design (LRFD) recommendations based on newly developed static analysis methods and the classification of S-IGMs. A back calculation approach is used to generate the appropriate damping parameters for S-IGMs for three distinct subsurface conditions utilizing a database of 34 steel H- and pipe piles. Newly developed WEAP and LRFD procedures are also recommended. Additional independent 22 test pile data are used to compare and evaluate the accuracy and efficiency of the proposed WEAP methods with the default WEAP method. Compared with the default WEAP, bearing graph analysis results revealed that the selected proposed WEAP method, on average, reduces the underprediction of pile resistances by 6% and improves the reliability with a 43% reduction in the coefficient of variation (COV). Calibrated resistance factors for the proposed WEAP method increase to as high as 0.75 compared to the current AASHTO recommendation of 0.50. An economic impact assessment reveals that the proposed WEAP method is more efficient than the default WEAP method as the average difference in steel weight for 32 test piles is 0.06 kg/kN, almost close to zero, reducing the construction challenges in the current engineering practice. [ABSTRACT FROM AUTHOR]

This paper presents a new tub girder series for Colorado, conforming to the articles of the American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications. Although the B618 tub girders developed by the Colorado Department of Transportation in the 1990s have been successfully used for decades, the need for an upgrade is essential to satisfy the requirements of contemporary bridge design and construction. After examining the performance of tub girders selected from six transportation agencies in the United States, an optimization algorithm was employed to generate efficient prototype sections. Then, detailed investigations were conducted to examine various practical aspects concerning the serviceability and ultimate limit states of AASHTO LRFD specifications. Parametric analysis with five bridge superstructures that accommodate up to four traffic lanes demonstrated the applicability of the prototype girders. A simplified version of the prototype sections was also delineated for regional precasters. Furthermore, a comparative study was carried out to evaluate the geometric stability and production costs of the prototype, simplified, and existing B618 girders. [ABSTRACT FROM AUTHOR]

Over the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance by providing different factors of safety for loads of distinct natures with regard to their probability of overload, frequency of occurrences and changes in point of application. The method also results in safer structures because it considers the behavior at collapse. While resistance factors for traditional construction materials based on LRFD in the National Building Code (NBC) of Canada are available, they cannot be used for non-conventional ones. This is because the resistance of such materials due to various load effects has unique bias factors (λR) and coefficients of variation (VR), which greatly impact their reliability index (β). In this study, relationships between the resistance factor ϕ and critical load effects from the NBC load combinations at ultimate limit states are developed for a wide range of resistance bias factors and coefficients of variation. The relationships are presented in the form of charts that are useful for researchers and code-writing professionals who have expertise in the various fields of structural engineering but lack proper background in reliability theory. The developed spectra showed that for the same ϕ, β increases with an increase in the live-to-dead load (L/D) ratio until it reaches 1; thereafter, the shape of the relationship will depend on the statistics of the resistance as well as on the magnitude of ϕ. For a small ϕ and VR, β will keep increasing with an increase in the L/D ratio from 1 until 3, albeit at a lesser rate. For L/D > 3, the relationship between the critical β and applied load is just about constant. This finding is also true for load combinations involving snow and wind. Application of the method is illustrated by a practical example involving the shear strength of a corrugated web steel beam. [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]

This paper investigates wind load distribution in float PV plants. Wave and wind load are dominant environmental load factors in determining design load in float PV plants. In particular, wind load is determined based on the numerical analysis results. The literature indicates that several input parameters exist, such as inlet angle and space between PV modules. An exemplary structure with ten arrays of PV modules was generated in this study. To investigate the wind load distribution in a float PV plant, the computational fluid dynamic (CFD) analysis was conducted with variables including wind direction (inlet angles) and three wind speeds (36.2, 51.7, and 70 m/s) in PV modules in the floating structure. Based on the numerical analysis, the wind load distribution of PV modules can be characterized with respect to the inlet angle and wind speed. The numerical results show that the wind loads in the central arrays are dominant. [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]

Pakistan has seen a burst of infrastructure development recently due to the increased connection between Asia and East Europe. The China–Pakistan Economic Corridor is a project between China and Pakistan aimed to improve the regional infrastructure that would ultimately enhance the connection between Asia and Eastern Europe. However, the active tectonics of Pakistan could put this infrastructure at risk if it is not built to the highest hazard prevention standard. This study reports the ground motion hazard by using the probabilistic seismic hazard assessment approach and the areal seismic source model. The seismic hazard maps of the China–Pakistan Economic Corridor in Pakistan are derived using the Cornell–McGuire (1968–1976) approach, which takes into account all earthquakes (25AD-2020) that occurred in Pakistan and nearby regions, the newest ground motion prediction equations, and an updated seismotectonic source model of Pakistan. The final ground motion intensities are attained as peak ground acceleration and 5% damped spectral acceleration at T = 0.2 s and 1.0 s for 475- and 2475-year return periods (estimated for bedrock site conditions). The results are displayed as color-coded maps that represent the amplitude deviation of ground motion. From the spatial evaluation of the maps, a peak ground acceleration value of 0.40–0.52 g for the 475-year return period and a spectral acceleration (0.2 s) value of 1.66–2.13 g for 2475-year return period are mostly observed on the northern and western routes. The central and eastern routes are mostly characterized by a peak ground acceleration value of 0.22–0.24 g for the 475-year return period and a spectral acceleration (0.2 s) value of 0.95–1.13 g due to diffused seismicity and lower number of faults in this region. The ground motion intensity values obtained in this study can be utilized for the seismic design of all kinds of infrastructure and bridges along the CPEC routes in accordance with the Building Code of Pakistan, the International Building codes, and the load and resistance factor design codes published by American Association of the State Highway and Transportation Officials. [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]

The load and resistance factor design (LRFD) method is normally used to design B-regions of reinforced concrete (RC) flexural members. The design includes many checks corresponding to different limit states. The LRFD method requires many loop calculation steps in the design, demonstrating its relative inefficiency. It cannot be applied to compare limit states directly and quantitatively. Different design limit states are separated and isolated. How to improve the analytical calculation efficiency of the LRFD method and to realize direct and quantitative comparisons between limit states are very important problems in structural engineering. This paper presents an innovative unified flexural resistance design (UFRD) method and a unified flexural resistance evaluation (UFRE) frame to solve these problems to some extent. The main contents include the unified flexural resistance (UFR) principles, formulas for the unified flexural resistance design (UFRD) method, the operation procedure to facilitate its usage, the UFRE framework to compare limit states, and three examples. The results show that the UFRD method can provide the same design outcomes as the LRFD one. However, UFRD calculations are simpler, requiring at most 20% of the calculation steps of the LRFD method. The UFRE frame can make different limit states compare with each other directly and quantitatively, which cannot be realized by the LRFD method. It helps expose some potential and insufficient flexural resistance hazards for some limit states, such as the only 10% relative strength reservation of one example. Thus, the UFRD method and the UFRE frame supplement and develop the LRFD method to some degree. The simplicity and practicality of the approach and the frame make them appropriate for many applications. [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]

Traditionally, the factor of safety (FOS) is widely used to account for uncertainties in the design of slopes within the framework of working stress design. As the uncertainties involved in the design of slopes vary, the same FOS may correspond to the different levels of reliability. In this study, the advanced first order reliability method is used to determine the resistance factors for design of slopes in a homogenous soil layer. It is found that the resistance factors depend on the target reliability index, the height of the slope, and the variability of the soil strength parameters. It is difficult to suggest a unique set of resistance factors for design of slopes. Analytic solutions are developed to determine the resistance factors for design of slopes assuming the random variables are normally distributed. An approximate method based on the concept of equivalent target reliability index is also suggested to determine the resistance factors for design of the slope when the soil strength parameters are lognormally distributed. The method suggested in this paper provides a practical way to perform load and resistance factors design of slopes. [ABSTRACT FROM AUTHOR]

Geotechnical design codes and guidelines are all switching from traditional factor of safety design to modern load and resistance factor design (LRFD) or partial factor design (PFD), in the belief that the latter two bring more flexibility and reliability consistency across various design scenarios, thus produce safe and cost-effective design outcomes. This paper first reviews the LRFD and PFD developed for geotechnical applications. A total of seven methods to calibrate the load and resistance factors are also introduced. The ability of the LRFD and PFD to produce designs with consistent reliability is examined and compared to that of a traditional factor of safety method using two examples of the bearing capacity of strip footings and the global stability of soil nail walls. Results showed that the framework of LRFD offers no apparent advantages over working stress design (WSD) in achieving more consistent reliability for geotechnical structures; the dispersion in design probabilities of failure could be five to seven orders of magnitude difference. The variation will be reduced to three orders if using the PFD. Neither reducing the variability in soil shear strength parameters nor allocating partial resistance factors with respect to soil types would efficiently harmonize the reliability levels when dealing with multiple soil layer conditions. In addition, the uniformity of reliability levels is insensitive to calibrations with or without presetting the load factors. This study provides insights into the LRFD and PFD frameworks currently developed for geotechnical applications. [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]

The present research work endeavours to study the shear performance of a 2-bolted clip-angle connector made of commonly available low-grade steel material (f y = 275-300 MPa) with 58 laboratory tests. The variability in the test specimens is achieved by varying the clip-angle thickness and its aspect ratio. The governing failure modes observed in the 2-bolted clip-angle are (i) Tearing failure for an aspect ratio (L/D) ≤ 0.23; (ii) Shear local buckling for an aspect ratio (L/D) > 0.23. An empirical shear equation for the 2-bolted clip-angle is developed by considering the present experimental data of low-grade steel material (f y = 275-300 MPa) and data in the literature for the high-grade (f y = 375-550 MPa) steel material. In addition, a new shear strength equation that applies to both 2-bolted and 3-bolted clip-angle of both high and low-grade steel strength is developed by the regression analysis of present 2-bolted and 3-bolted clip-angle experimental results from the literature. The proposed new shear strength equation is expressed as a function of L/D to represent the failure behavior of the bolted clip angles. Hence, the proposed new shear equation is applicable for all the bolted clip-angle connections under a shear load in a CFS beam-to-column connection and presents the corresponding failure mode as well. The design factors of Load and Resistance Factor Design (LRFD), Limit State Design (LSD) and Allowable Strength Design (ASD) methods were evaluated for the proposed shear equations by the reliability analysis. [Display omitted] • Shear behavior of the 2-bolted connection (2BS) studied for the low-grade (f y = 275–300 MPa) steel. • An improved shear equation for 2BS connection was developed from present and literature data. • A new set of equations as a function of failure modes was developed for CFS bolted connection. • Reliability analysis was conducted and design factors were evaluated. [ABSTRACT FROM AUTHOR]

The principal objective of this investigation is to furnish equations to compute the design strength of fillet welds under in-plane eccentric loads suitable for load and resistance factor design (LRFD) applications. Over the years, experimental and analytical techniques have been used to arrive at safe estimates for the strength of such welds in common practical applications. The conventional elastic design (ED) method is very conservative and is not compatible with the LRFD design philosophy. In addition, the ED method neglects the weld group's ductility and strain compatibility. On the other hand, the instantaneous center of rotation (IC) method considers the above parameters but requires complex calculations. In the present study, a method for designing fillet welds under eccentric loading is introduced called the plastic design (PD) method. This method considers the inelastic properties of the welds in a simple manner while providing an accurate prediction of the weld group's capacity. The performance of the proposed PD method was compared with the IC method for several cases. The ultimate loads obtained were mostly within 10% difference on the conservative side and only marginally different for a few. Additionally, the fillet weld group's resistance under in-plane eccentric loads was evaluated experimentally using 12C-shaped specimens with the load applied at different angles of 0, 45, and 75°. The test results also confirmed the efficacy of the proposed PD method in evaluating the design strength of such weld groups. [Display omitted] • Fillet welds under in-plane eccentric loads were studied. • To predict the fillet weld strength a new Plastic Design (PD) method was proposed. • The PD method results revealed a great improvement as compared to classical elastic design method. • As compared with complex IC method, PD strength predictions showed acceptable accuracy. • 12 experimental specimens also validated the applicability of the PD method. [ABSTRACT FROM AUTHOR]

A series of numerical simulations were completed to investigate the behavior of intact, fire-damaged, and Carbon Fiber-Reinforced Polymers (CFRP) retrofitted reinforced concrete (RC) bridge columns of varying sizes subjected to vehicle collisions. Three-dimensional finite element models of isolated RC columns and their foundation systems surrounded by soil volumes were developed using LS-DYNA. A comprehensive parametric study was carried out to investigate the effects of nine demand and design parameters on the performance of bridge columns. Studied parameters included: column diameter, column height, unconfined compressive strength, steel reinforcement ratio, fire duration, CFRP wrap thickness, wrapping configuration, vehicle's mass, and vehicle's speed. For each studied scenario, Peak Twenty-five Milli-second Moving Average (PTMSA) was employed to estimate the Equivalent Static Force (ESF) corresponding to each vehicle collision scenario. Resulting ESF s were then utilized to assess effectiveness of the current ESF approach available in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO-LRFD) Bridge Design Specification for analyzing and helping design bridge columns under vehicle collision. Multivariate nonlinear regression analyses were used to derive an empirically based, simplified equation to predict the ESF that corresponds to a vehicle collision. Rather than constant design force, this equation established a correlation between ESF and kinetic energy, column axial capacity, and column height. Results indicated that the proposed equation is reliable and can accurately predict ESF s over a diverse range of collision scenarios that included intact, fire damaged, and CFRP retrofitted columns. To facilitate realistic implementation of the derived equation, an ESF assessment framework was also devised. • Performance assessment and insights on intact, fire-damaged, and CFRP retrofitted bridge pier columns under vehicle impact. • Developed 3D finite element models of isolated bridge column, foundation system, and surrounding soil domain using LS-DYNA. • Conducted a comprehensive parametric study including nine demand and design variables. • Derived an empirically based, simplified equation that predicts ESF over a wide range of vehicle collision scenarios. • Proposed an assessment framework to facilitate the implementation of the proposed equation. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) has emerged as a prominent choice for structural components and sections in the construction industry. The primary focus of this Special Issue is to disseminate the latest innovative research on CFS sections, aiming to positively impact the structural design and analysis of steel infrastructure. Non-linear finite element analysis and advanced optimization algorithms play essential roles in investigating the performance of CFS sections and achieving optimization [[11]]. [Extracted from the article]

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]

Steel frame with steel plate shear walls (SPSWs) is used to resist lateral loads caused by wind and earthquakes in high-rise buildings. In this load-resisting system, the cost and performance are more efficient than in the moment frame system. Behaviors of beam-to-column connections are assumed to be pinned or fixed to simplify the calculation in the past few decades. However, studies have stated that such a simulation fails to reveal the response of beam-to-column connections. In this paper, a newly developed metaheuristic optimization algorithm—the dolphin echolocation algorithm (DE)—based on foraging prey using echolocation in dolphins is applied as the present study optimizer. Two different two-dimensional semirigid connection steel frames with SPSWs are optimized to obtain the minimum cost of semirigid connection steel frame with steel plate shear walls with constraints to element stresses and story drift ratio according to the American Institute of Steel Construction (AISC) Load and Resistance Factor Design (LFRD). SPSW is modeled as a brace with equivalent lateral stiffness, while the P − △ effects are considered in the steel frame. Semirigid connections are used to reveal the actual responses of beam-to-column connections. The results demonstrate the proposed method's effectiveness for optimizing semirigid connection steel frames with SPSWs and the interaction between semirigid connections and the SPSWs. [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]

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.

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]

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]

Load and resistance factor design (LRFD) is widely used in building codes for reliability design. In the calculation of load and resistance factors, the third-moment method (3M) has been proposed to overcome the shortcomings (e.g., inevitable iterative computation, requirement of probability density functions (PDFs) of random variables) of other methods. With the existing 3M method, the iterative is simplified to one computation, and the PDFs of random variables are not required. In this paper, the computation of load and resistance factors is further simplified to no iterations. Furthermore, the accuracy of the proposed method is proved to be higher than the existing 3M methods. Additionally, with the proposed method, the limitations regarding applicable range in the existing 3M methods are avoided. With several examples, the comparison of the existing 3M method, the ASCE method, the Mori method, and the proposed method is given. The results show that the proposed method is accurate, simple, safe, and saves material. [ABSTRACT FROM AUTHOR]

The total ultimate resistance (or bearing capacity) of driven piles considering setup effects is composed of initial ultimate resistance and setup resistance, and the setup effects of driven piles are mainly reflected by the setup resistance. In literature, a logarithmic empirical formula is generally used to quantify the setup effects of driven piles. This paper proposes an increase factor (Msetup) to modify the resistance factor and factor of safety calculation formula in accordance with the load and resistance factor design (LFRD) principle; here, the increase factor is defined as the ratio of the setup resistance (Rsetup) to the initial ultimate resistance (R0) of driven piles. Meanwhile, the correlation between R0 and Rsetup is fully considered in the resistance factor and factor of safety calculation. Finally, the influence of four key parameters (ratio of dead load to live load ρ = QD/QL, target reliability index βT, Msetup, correlation coefficient between R0 and Rsetup, ρR0,Rsetup) on the resistance factor and factor of safety are analyzed. Parametric research shows that ρ has basically no effect on the resistance factor, which can be taken as a constant in further research, and ρ has a significant influence on the factor of safety. The value of Msetup has almost no effect on the resistance factor and factor of safety. However, βT and ρR0,Rsetup have a significant influence on the resistance factor and factor of safety, so the value selection of βT and ρR0,Rsetup are crucial for reliability-based design of driven piles. Through this study, it is concluded that considering setup effects in reliability-based design of driven piles will greatly improve the prediction for design capacity. [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]

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]

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]

This work provides a state-of-the-art report on the current knowledge concerning the structural behavior and design, by means of the Direct Strength Method (DSM), of steel equal-leg angle columns with short-to-intermediate lengths, that is, those buckling in flexural–torsional modes – although cold-formed columns constitute the main focus of the paper, hot-rolled columns are also addressed. The columns dealt with are either fixed-ended or simply supported – the latter designation includes columns with both cylindrically and spherically-hinged end cross-sections. Initially, numerical results concerning the mechanics underlying the buckling and postbuckling behavior of the previous angle columns are presented and discussed: (1) highlighting the main differences between the fixed-ended and simply supported column responses, and (2) evidencing the need for specific design procedures. Next, the paper collects the experimental and numerical failure load data available in the literature, reported by various researchers and dealing with cold-formed and hot-rolled fixed-ended and simply supported columns with several geometries (cross-section dimensions and lengths). Then, the paper presents the mechanical reasoning behind a recently proposed novel DSM-based design approach, as well as the main steps involved in developing and calibrating the corresponding strength curves. Finally, the merits of this design approach are assessed through (1) the estimation quality of the available failure load data, and (2) the evaluation of the associated Load and Resistance Factor Design (LRFD) resistance factors, which are compared with those currently recommended by the North American Design Specifications. The paper closes with an overview of the findings reported and a reference to future developments of this research effort. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to present a new solution for simultaneous shape and size optimization of double-layer grids. In order to find the optimum design, Enhanced Colliding Bodies Optimization method is applied to the optimum design of the most common examples of double-layer grids, while both material and geometrical nonlinearity are taken into account. The small and big sizes of span length are considered for each type of square grids. The algorithm gets the minimum weight grid by finding the best nodal location in z-direction (height of the structure) and the suitable selection from the list of tube sections available in American Institute of Steel Construction Load and Resistance Factor Design, simultaneously. All examples are optimized with strength and displacement constraints. The numerical results demonstrate the efficiency and robustness of the presented method for solving real-world practical double-layer grids. [ABSTRACT FROM AUTHOR]

The empirical approach adapting the Stress History and Normalized Soil Engineering Properties (SHANSEP) concept relates the average overconsolidation ratio (OCR) of plastic soils to the average pile side adhesion normalized to the effective overburden stress. Additional pile case histories were identified and used to expand an existing database and slightly revise the side adhesion design model. The data set then was used to calibrate resistance factors for the SHANSEP-based design model within the Load and Resistance Factor Design (LRFD) framework. The resistance factors derived provide a significantly greater nominal capacity than those presently available in the AASHTO code due to the accuracy of the SHANSEP-based design approach. For example, piles loaded in compression and for bridge spans with a dead-to-live load ratio of three returned resistance factors equal to 0.875 and 0.769 for reliability indexes of 2.33 and 3.09, respectively, in the absence of variability in OCR. Resistance factors then were calibrated in consideration of the uncertainty in OCR to allow the practitioner to directly consider the uncertainty in stress history in the reliability of the SHANSEP design approach. Reductions in the resistance factors ranged from 2% to 67% for coefficients of variability in OCR ranging from 5% to 50%. The reliability-based SHANSEP approach for side resistance represents a significant improvement over currently accepted design models in the AASHTO code and can be directly used to justify improved site investigation. [ABSTRACT FROM AUTHOR]

Background: Modifying variables in exercise prescription can produce specific effects on Achilles tendinopathy outcomes. This study aims to determine the feasibility of conducting an adequately powered randomised trial in the future to assess the efficacy of different load intensity and time-under-tension exercise parameters for improving pain and function in individuals with persistent midportion Achilles tendinopathy. Methods: The trial is designed as prospective, four-armed feasibility and randomised pilot trial with 3 months follow-up. Interventions will be provided in a gym setting. The investigator, who will be blind to the allocation of participants, will conduct all pre- and post-intervention assessments. Forty-eight male participants with Achilles tendinopathy will be recruited from the community. We will use a 2 × 2 factorial design with factors of load intensity (six or eighteen repetitions maximum) and time-under-tension (two or six second repetitions). Participants will be randomised into one of the testing groups: six RM with two second repetitions, six RM with six second repetitions, eighteen RM with two second repetitions or eighteen RM with six second repetitions. Trial feasibility will be indicated by the rate of conversion, recruitment and retention, adherence to the interventions by participants, the utility of videoconferencing mode for weekly exercise supervision, incidence of adverse events, and feasibility of future economic evaluation. The secondary clinical outcomes will assess pain and disability, participant impression of change, satisfaction, health-related quality of life, physical activity, work absenteeism, psychological measures at baseline, 6 and 12 weeks, and plantarflexor contractile dysfunction (torque, rate of force development and muscle force steadiness) at baseline and 12 weeks. These clinical outcomes are primarily measured to provide information regarding potential treatment effects and trends. Discussion: The proposed study and follow-up powered randomised trial will be a first step towards determining exercise dose parameters that may optimise outcomes for Achilles tendinopathy. We have chosen to focus on load intensity and time-under-tension, as these parameters are important for tendon adaptation. This work has the potential to lead to more effective exercise loading interventions for Achilles tendinopathy. Trial registration: Australian New Zealand Clinical Trials Registry, ACTRN12618001315202. Registered retrospectively on August 6th, 2018. [ABSTRACT FROM AUTHOR]

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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]