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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]

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]

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]

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]

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]

This paper presents the improvement of load and resistance factor design (LRFD) method for axially loaded driven piles in Iran. The LRFD method has been well developed and successfully implemented in geotechnical engineering, especially in the design of pile foundations in different parts of the world. To extend the use of this method in Iran, it is necessary to use the results of reliable local pile load tests and construction records to calibrate LRFD resistance factors regionally. To this end, we first collected a comprehensive database of static and dynamic load tests which have been performed on driven piles in fine-grained soils across Iran. Based on this database, we calculated the resistance factors for different design methods using three different methods of reliability analysis (FORM, FOSM, and MCS) and for two levels of reliability (βT = 2.33 and 3). Finally, we used these calculations together with experience and engineering judgment to propose resistance factors for the National Building Code of Iran. [ABSTRACT FROM AUTHOR]

One key aspect of efficient transport is load factor: the load carried compared to the maximum load that could be carried in a load unit (e.g. a vehicle). The purpose of this study is to develop an approach that will clarify and describe ways in which shippers can measure load factor. Drawing on existing literature and understanding gained from empirical data the proposed approach uses the load factor model, which structures measurement of load factor overall and at several levels (packaging, shipping, vehicle, fleet) as the ratio of required to available capacity. Shipping level includes utilization of purchased capacity, which is of special interest to shippers. For applying the model in practice, calculation methods linked to availability of data are presented. Calculations of volumetric load factor from two cases illustrate the methods. This paper's detailed descriptions of how shippers can measure load factor provide calculation structure as well as transparency. Measuring load factor is of interest to evaluate efficiency, particularly since load factor is related to transport costs and environmental performance. [ABSTRACT FROM AUTHOR]

Results of several full scale RC (reinforced concrete) pile load tests were studied and analyzed to create a comparison between the MLT (maintained load test) and PDA (pile driving analyzer) methods. The ultimate pile capacities derived from analysis of PDA were consistently higher than results from the MLT. A coefficient of 0.9 or a 10% reduction is suggested to be applied to values derived from PDA. It is also observed that the longer the time interval, the greater the shaft friction contribution is towards the pile capacity. [ABSTRACT FROM AUTHOR]

The uniaxial compressive strength (UCS) of rocks is a critical parameter required for most geotechnical projects. However, it is not always possible for direct determination of the parameter. Since determination of such a parameter in the lab is not always cost and time effective, the aim of this study is to assess and estimate the general correlation trend between the UCS and indirect tests or indexes used to estimate the value of UCS for some granitoid rocks in KwaZulu-Natal. These tests include the point load index test, Schmidt hammer rebound, P-wave velocity (V) and Brazilian tensile strength (σ). Furthermore, it aims to assess the reliability of empirical equations developed towards estimating the value of UCS and propose useful empirical equations to estimate the value of UCS for granitoid rocks. According to the current study, the variations in mineralogy, as well as the textural characteristics of granitoid rocks play an important role in influencing the strength of the rock. Simple regression analyses exhibit good results, with all regression coefficients R being greater than 0.80, the highest R of 0.92 being obtained from UCS versus σ. Comparison of equations produced in the current study as well as empirical equations derived by several researchers serves as a validation. Also illustrate that the reliability of such empirical equations are dependent on the rock type as well as the type of index tests employed, where variation in rock type and index tests produces different values of UCS. These equations provide a practical tool for estimating the value of UCS, and also gives further insight into the controlling factors of the strength of the granitoid rocks, where the strength of a rock is a multidimensional parameter. [ABSTRACT FROM AUTHOR]

This paper presents reliability analyses of soil nail walls against two external ultimate limit states, global and sliding stabilities, which are related to the external stability failures of soil nail walls. Reliability analyses are conducted using Monte Carlo simulation technique. Soil nailing is a popular retaining system in highway construction and slope stabilization, and its current design practice is still based on the working stress design. There remains a need to establish a more rational design framework-load and resistance factor design-based on the concept of limit state design and reliability analysis for soil nail walls. The development of load and resistance factor design approach must consider multiple ultimate limit states, associated with external, internal, and facing failures. The analyses of resistance factors against two external failures are conducted in this study considering various influencing factors, including statistical parameters of soil friction angle, ultimate bond strength between soil and nails, soil type, wall geometry (wall height, back slope angle, and face batter angle), and nail configurations (nail inclination angle, drillhole diameter, and nail spacing). In the end, a series of resistance factors are proposed for potential application of load and resistance factor design approach against external failures for soil nail walls according to different design codes. [ABSTRACT FROM AUTHOR]

Creep-fatigue tests of 9Cr-1Mo-V-Nb steel have been conducted under load control with further study of the steel mechanical degradation via microscopic observation, static-mechanical analysis and ultrasonic evaluation. The tempered specimens exhibited a tempered martensitic structure with a high dislocation density in the lath interior and fine precipitates on the previous austenite grain and martensite lath boundaries. However, the major microstructure changes to the 9Cr-1Mo-V-Nb steel caused by creep-fatigue were the coarsening of CrC precipitates, the recovery of dislocations due to rearrangement and annihilation, an increase in the martensite lath width, and the formation of cavities. The ultrasonic velocity was observed to increase rapidly within the initial fatigue life fraction (stage I), but the attenuation decreased during this stage. During stage II, there was a slight increase in the ultrasonic velocity and the attenuation subsequently decreased. The ultrasonic velocity decreased and the attenuation increased during the final period (stage III) of fatigue life. [ABSTRACT FROM AUTHOR]

The coaxing effect in fatigue refers to an increase in the fatigue strength of material imduced by prior cycling at a stress level below the fatigue limit. In this study, the coaxing effect of multi-level stresses in the fatigue process in the automotive drive shaft material 40Cr was investigated by applying three levels of stress amplitudes below the fatigue limit in different sequences prior to conducting the conventional constant amplitude fatigue test with standard round bar specimens. The existence of coaxing effect under multi-level stress with a load sequence effect was observed and confirmed by the results. The longest fatigue life is achieved through three levels of coaxing load with a step increase sequence, while a decrease sequence will result in the shortest fatigue life. The mechanisms of the coaxing effect which increased the fatigue life at the crack initiation and propagation stages were observed, through fracture morphology analysis, as the regulation of micropores, decreasing of pore density and the narrowed striation spacing. This finding is instrumental for extending the service life of mechanical components. [ABSTRACT FROM AUTHOR]

In a compartment fire, externally venting flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings; EVF-induced risks are constantly growing due to the ever-increasing trend of using combustible materials in building facades. The main aim of this work is to investigate the fundamental physical phenomena associated with EVF and the factors influencing their dynamic development. In this context, a series of fire tests is conducted in a medium-scale compartment-façade configuration; an n-hexane liquid pool fire is employed, aiming to realistically simulate an 'expendable' fire source. A parametric study is performed by varying the fire load density (127.75, 255.5 and 511 MJ/m) and ventilation factor (0.071 and 0.033 m). Emphasis is given to characterization of the thermal field developing adjacent to the façade wall. Experimental results suggest that the three characteristic EVF phases, namely 'internal flaming', 'intermittent flame ejection' and 'consistent external flaming', are mainly affected by the opening dimensions, whereas the fuel load has a notable impact on the fuel consumption rate and heat flux to the façade. Fuel consumption rates were found to increase with increasing fire load and opening area, whereas the global equivalence ratio increases with decreasing opening factor. The obtained extensive set of experimental data can be used to validate CFD fire models as well as to evaluate the accuracy of available fire design correlations. [ABSTRACT FROM AUTHOR]

In industry, due to conservative system design, safety factors associated with uncertainty in the load requirements, discrete availability of commercial rated power, and/or load power variation, most three-phase squirrel-cage induction motors are oversized. Besides the extra capital investment, the oversizing of direct-on-line fixed-speed induction motors can lead to a significant efficiency and power factor reduction. However, the part-load efficiency of oversized motors can still be higher than the full-load efficiency of well-sized smaller motors because, in general, the nominal efficiency increases with the rated power. In this paper, an analysis of potential benefits and drawbacks of motor oversizing is carried out. On the basis of the catalogue technical data provided by one of the largest motor manufacturers for IE1-, IE2-, IE3-, and IE4-class four-pole induction motors, the main results of a simulation-based study on the oversizing energy efficiency and cost-effectiveness are presented. A method to estimate the motor efficiency and power factor for any load level using commercial catalogue data is proposed and applied. Some technical issues associated with motor oversizing are also briefly addressed. It is shown that, if the additional reactive energy consumption due to poorer power factor and the slight speed increase are ignored, for IE1-, IE2- and, to a much less extent, IE3-class motors, oversizing can be cost effective for many motor rated powers, resulting in a higher average efficiency and a lower motor lifecycle cost, as well as in an extended motor lifespan. For most IE3- and IE4-class motors, the oversizing is not cost effective because of the lower nominal efficiency gain when moving to a higher oversized rated power. Additionally, the oversizing impact on the motor energy consumption strongly depends on the load profile of the application. When an old motor fails, it will probably be an IE0- or IE1-class equivalent motor, and this situation provides a golden opportunity for replacing the old motor with a properly sized IE3- or IE4-class motor, which offers significantly higher efficiency for a wide range of loads. [ABSTRACT FROM AUTHOR]

Beghini et al. (Struct Multidisc Optim 50:49-64, ) have published a very interesting paper arriving to practically the same nearly optimal solutions for the so named 'bridge problem' that the writers published a year before, but using an alternative and remarkable approach to the problem. In spite of this general agreement, the writers think that some details of the paper can be improved and there are results that can be given a clear and meaningful interpretation, thanks to an old and practically unknown theorem on optimal slenderness. [ABSTRACT FROM AUTHOR]

In particular, it is argued that geotechnical data can be rich if generic databases are considered together with the site-specific data, new sensing and monitoring technology. Chapter 2 introduces the various sources of uncertainty in geotechnical engineering and statistical tools and methods to deal with data. This book has provided excellent examples on how to treat the data as the "digital twin" of the physical asset and how to use the database to improve the design and decision-making in geotechnical engineering. [Extracted from the article]

Substantiation of the choice is considered for an alternative 20G grade low-alloy structural steel instead of structural steel 40 for manufacturing bottom-hole pumping rod joint couplings. Steel 20G is most economic, available, and in many ways is no worse than steel 40. Laboratory and industrial tests are carried out for testing couplings prepared from steel 20G. It is established that with respect to the criterion of thread cutting the safe load factor is 5.75-9.84. [ABSTRACT FROM AUTHOR]

A reliable prediction of the strata behavior and support capacity of longwall workings has always been a challenge for mining engineers. It is still difficult to quantitatively predict some important mining parameters, such as support capability and the interval of periodic caving of the major roof under given mining and strata conditions. The reason is that several factors controlling the strata behavior are difficult to determine, such as the bulk factor of the caving zone, strength factor of the major roof and load factor of the overlying rock strata. In this study, the back analysis method is employed to address this problem. This paper illustrates an integrated approach to predict the strata movement behavior and optimum capability of powered roof supports for safe mining. First, this approach uses the empirical method to qualitatively analyze the mining influence zone, then establishes a quantitative prediction model by theoretic analysis method, and solves the optimum values of the factors described in the model with the back analysis method. On the basis of the above research, the support capability and interval of periodic caving of the major roof under similar geological conditions may be calculated by using these suitable values of the factors. Finally, an illustration of the above process is presented in this paper to examine the reliability of this approach. [ABSTRACT FROM AUTHOR]

Detailed geotechnical investigations were performed at two sites within the state of Arkansas (Monticello and Turrell). The soil parameters, predicted axial capacity, and predicted load-movement response values varied depending on (1) which geotechnical investigation methods and/or (2) which predictive software programs (FB-Deep, SHAFT) were utilized. The uncertainty associated with the different soil properties and the discrepancies between the different software programs are discussed. Parametric and nonparametric statistical testing methods, including the: T-test, F-Test, and Wilcoxon test were utilized to evaluate the soil parameters (corrected blow count, total unit weight, and undrained shear strength) and the predicted axial capacity data. No statistical differences (95 % confidence interval) were observed for the respective undrained shear strength, total unit weight (clay), and correlated corrected blow count parameters as determined from University of Arkansas (UofA) method and from Missouri Department of Transportation (MODOT) method. However, differences were observed for the predicted axial capacity and load-movement values that were predicted using the aforementioned soil parameters (percent differences ranging from 0.5 to 29.2 % for load-movement values). Because an inverse relationship was observed between the percent difference in the load-movement values and the number of statistically similar soil properties, it was determined that the predicted axial capacity and predicted load-movement response were dependent upon the soil sampling and testing methods and the utilized software program. [ABSTRACT FROM AUTHOR]

Breakdown of air tightness due to a variation in load is possible in detachable airtight joints as the temperature of their constituent elements varies. Methods of assuring the constancy of the load independently of any variation in temperature for the flange connection and a stuffing box seal with soft stuffing and calculations of the parameters necessary to achieve this objective are presented. [ABSTRACT FROM AUTHOR]

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle. [ABSTRACT FROM AUTHOR]

In this paper, a new efficient optimization algorithm called Teaching-Learning-Based Optimization (TLBO) is used for the optimum design of grillage systems based on the LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Construction). Cross sectional area of W-shapes are considered as discrete design variables. Various grillage structures are designed to show the efficiency of the TLBO algorithm. The results obtained from this study are compared with those reported in the literature. It is concluded that the TLBO algorithm presented in this study can be effectively used in the optimal design of grillage structures. [ABSTRACT FROM AUTHOR]

During a fire resistance test for validating the fire resistance performance of a building's structural members, a member is generally exposed to flames while being applied with a defined load ratio. In the case of a member capable of bearing a large load, the load may not be applied at the corresponding defined load ratio. In this case, an additional procedure to check the fire resistance needs to be performed through analysis or document research. In this study, two different load ratios were applied to specimens comprising of two different sections in a Korean asymmetric floor beam, respectively, to conduct tests to validate fire resistance performance. Analysis was conducted using the finite element software ANSYS and the results were compared to validate the analysis model. The analysis model that was verified was used to analyze the fire resistance behaviors in four types of Korean asymmetric floor beams according to load ratio. Based on the results of the analysis, the fire resistance and limiting temperature of each model for a load ratio of 0.1 units were presented. [ABSTRACT FROM AUTHOR]

In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD) specifications are formulated based on failure probabilities, which are fully calibrated for dead load and non-extreme live loads. Design against earthquake load effect is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction (or increased scour depth). Furthermore, scour effect cannot be linked directly to an LRFD limit state equation because the latter is formulated using force-based analysis. This paper (in two parts) presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based failure calculations. In Part I of this series, the general principle for treating the scour depth as an equivalent load effect is presented. In Part II, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load effect are quantitatively discussed. The key formulae of the conditional partial failure probabilities and the necessary conditions are established. In order to illustrate the methodology, an example of dead, truck, earthquake and scour effects on a simple bridge pile foundation is represented. [ABSTRACT FROM AUTHOR]

The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In Part II of this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. There are three major steps in establishing load factors from MH load distributions: (1) formulate the failure probabilities; (2) normalize various load distributions; and (3) establish design limit state equations. This paper describes the formulation of the failure probabilities of single and combined loads. [ABSTRACT FROM AUTHOR]

The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variable and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. [ABSTRACT FROM AUTHOR]

It is well-known that a single tensile overload, during the fatigue crack growth under constant loading amplitude, can induce the delay phenomenon. One of the basic mechanisms for fatigue crack growth in ductile metals is based on the crack-tip blunting under tensile loads. In this article, we investigate the fatigue crack growth delay behavior due to the single overload in the case of 12NC6 steel through compact tension specimens. An analytical method based on properly modified εN concepts is presented to predict the delay lives. The combination knowledge of the short cracks and the 3D constraint effect is important for the analysis in the vicinity of the blunt crack tip after overload. The present approach provides an analytical means to quantify the crack delay cycles in fatigue following a single tensile overload. The experimental results are in good agreement with the analytical modeling for different overload distributions. [ABSTRACT FROM AUTHOR]

Construction on expansive soils can generally be resolved using piles. Where shallow foundations are used in these materials, the swelling pressure should be determined and the foundations designed to provide a greater pressure to counteract this. Clearly, it will also be necessary to determine the capacity of the ground to take this load. The paper discusses the bearing capacity of unsaturated expansive soils for a given suction value and notes the bearing capacity was increased by 26% when the effect of suction was taken into account. However, an increase in the water content would cause a decrease in suction and hence a decrease in the bearing capacity. [ABSTRACT FROM AUTHOR]

This paper examines the control of entities having two degrees of freedom on the basis of external-load prediction. Models of zero- and first-order loadings, and also a method for common construction of a loading model with respect to both coordinates are presented. [ABSTRACT FROM AUTHOR]

This study was concerned with the drop performance between the Sn37Pb and the Sn3.8Ag0.7Cu (wt. %) solder joints when the specimens were subjected to drop test after soldering process. The U-notch butt-jointed specimen was adopted and a lab-designed drop tester was employed. Meanwhile, the electrical resistance values of two kinds of solder joints were measured and recorded after certain drop tests, and finally drop number versus resistance curves were plotted and compared. From the resistance variation with the drop number, it was observed that the Sn37Pb joints presented significantly higher drop performance than the Sn3.8Ag0.7Cu ones. For the Sn3.8Ag0.7Cu specimens, the average drop number before failure was approximately 15-18 and then the resistance values sharply increased. However, the average drop number of the Sn37Pb joints was over 110 and the increasing rate of the electrical resistance was smooth, which is consistent with the results of the board-level drop test. Moreover, one specimen of each kind was picked out and the microstructural observation was carried out to investigate the joint deformation behavior in the dynamic load. It was obvious that the plastic deformation capacity of the Sn37Pb joints was remarkably higher than the one of the Sn3.8Ag0.7Cu joints, proving that most of SnAgCu-based solders presented low deformation compatibility and low energy absorption. [ABSTRACT FROM AUTHOR]

The article demonstrates examples of the classical two-way body problem on the methods for deriving equations for dynamical process and the existence of orbits in gravitational fields within the Minkowski space. It refers to the extremal dimension theory which expressed the possibility to obtain the exact equations of motion for dynamical processes without limiting assumptions by means of real motions depending on the level of knowledge about the environment, extremum, and to a dimensional quantity. Moreover, its also expresses the possibility to derive by the use of purely mathematical means such as the existence of differential equation on the motion of trajectories, inertial overloads, and trajectories with and without overloads and reversible time.

The general authority of road, bridges, and land transportation (GARBLT) specify the limitation of truck loads that run on Egyptian highways. Many trucks violate these limits by loading additional weights to decrease the transportation unit cost. This behavior causes severe deterioration to the pavement. Such violating trucks are charged by eventually little penalties compared to the damage they cause to the pavement. The objectives of this study is to evaluate the effect of increasing axle load, due to overloaded trucks, on the pavement life and to estimate a critical load that makes a boundary between penalized loads and the unallowable loads by developing a relationship between the number of load repetition to failure and axle load. The research used the KENPAVE software to calculate the horizontal tensile strain occurring at the bottom of the asphalt layer and the vertical compressive strains occurring at the top the subgrade soil due to the different axle loads. The calculated strains are then utilized to estimate the number of load repetitions to failure due to fatigue cracking using the Asphalt Institute (AI) method. Finally, relationships relating the predicted numbers of load repetitions with axle load and tire pressure were developed using regression analysis. In this study, Cairo - Alexandria desert highway was used as a case study. [ABSTRACT FROM AUTHOR]

The initiation of multiple cracks in a fiber/matrix composite subjected to a torsional load is studied. The composite is made of a cylindrical fiber surrounded by a matrix of different properties. A periodic array of cracks is assumed to exist in the fiber along its central axis. A dual integral equation is formulated in terms of equivalent crack face loads. The effects of crack spacing on the crack tip field intensity factor, the stress, the torque, and the equivalent stiffness of the fiber are investigated and displayed graphically. [ABSTRACT FROM AUTHOR]

The static response of simply supported functionally graded plates (FGP) subjected to a transverse uniform load (UL) or a sinusoidally distributed load (SL) and resting on an elastic foundation is examined by using a new hyperbolic displacement model. The present theory exactly satisfies the stress boundary conditions on the top and bottom surfaces of the plate. No transverse shear correction factors are needed, because a correct representation of the transverse shear strain is given. The material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of material constituents. The foundation is modeled as a two-parameter Pasternak-type foundation, or as a Winkler-type one if the second parameter is zero. The equilibrium equations of a functionally graded plate are given based on the hyperbolic shear deformation theory of plates presented. The effects of stiffness and gradient index of the foundation on the mechanical responses of the plates are discussed. It is established that the elastic foundations significantly affect the mechanical behavior of thick functionally graded plates. The numerical results presented in the paper can serve as benchmarks for future analyses of thick functionally graded plates on elastic foundations. [ABSTRACT FROM AUTHOR]

We present a simple theory of actions against the background of branching time, based on which we propose two versions of an extended stit theory, one equipped with particular actions and the other with sets of such actions. After reporting some basic results of a formal development of such a theory, we briefly explore its connection to a version of branching ETL. [ABSTRACT FROM AUTHOR]

It is known that sign of T-stress in cracked specimens affects fracture toughness under mixed mode conditions. We suggest a new test involving an inclined edge cracked semi circular specimen subjected to asymmetric three-point bend loading (IASCB specimen) that covers a broad range of modes I and II SIFs and T-stress values. It can provide both positive and negative T-stresses. This is illustrated by FEM computations. [ABSTRACT FROM AUTHOR]

In this work, the applicability of a procedure based on the load separation criterion in determining the fracture resistance ( JIc) of a rubber modified polyamide 66 (PA66) was analyzed and discussed. In particular, the effects of the testing conditions, with particular reference to geometry and loading rate, on the applicability of the method were investigated. The tests were performed both at low (from 0.5 to 50 mm/min) and moderately high (0.6 m/s) loading rates, on single edge notched in bending specimens with different initial crack length to width ratios ( a0/ W), which ranged between 0.3 and 0.7. Among the various findings it is worthwhile to point out that this analysis revealed that the plastic displacement at the end of the blunting process (at fracture initiation) resulted geometry independent. A clear dependence of such a parameter on the loading rate was observed. Further, it was shown that load separation is maintained beyond the blunting phase, as observed in the experiments carried out at low rate. [ABSTRACT FROM AUTHOR]

The dynamic behavior of a three-layer elliptic cylindrical shell is studied and associated problems are formulated. The refined Timoshenko model is used. The numerical method used to solve the equations of motion is based on the integro-interpolation differencing method. The dynamic behavior of a three-layer elliptic cylindrical shell under a distributed nonstationary load is studied. [ABSTRACT FROM AUTHOR]

The article focuses on the methodology used in the load testing of the concrete viaducts in the North-South railway crossing in Lisbon, Portugal. It describes how the static loading and dynamic loading tests were done using two locomotives pulling two or three water wagons as live loads. It concludes that bridge authorities and structural designers can use static and dynamic load testing as it provides a fundamental tool for the assessment of their structural performance.

Based on the analytical model for the plastic limit state, a numerical procedure for estimating the remaining strength of a complex-shaped defect has been developed. Comparison of the calculation results obtained by the proposed procedure with the experimental data and the calculation results obtained by other methods showed its efficiency. [ABSTRACT FROM AUTHOR]

The problem of estimating bounds to shakedown loads for problems governed by a class of deviatoric plasticity models including those of Hill, von Mises, and Tresca is addressed. Assuming that an exact elastic solution is available, an upper bound to the elastic shakedown multiplier can be obtained relatively easily using the plastic shakedown theorem. A procedure for computing this upper bound for arbitrary load domains is presented. A number of problems are then examined and it is found that the elastic shakedown factor is given as the minimum of the plastic shakedown factor and the classical limit load factor. Finally, some exact solutions to a number of two dimensional problems are given. [ABSTRACT FROM AUTHOR]

Parallel implementations of dynamic structured adaptive mesh refinement (SAMR) methods lead to significant runtime management challenges that can limit their scalability on large systems. This paper presents a runtime engine that addresses the scalability of SAMR applications with localized refinements and high SAMR efficiencies on large numbers of processors (upto 1024 processors). The SAMR runtime engine augments hierarchical partitioning with bin-packing based load-balancing to manage the space-time heterogeneity of the SAMR grid hierarchy, and includes a communication substrate that optimizes the use of MPI non-blocking communication primitives. An experimental evaluation on the IBM SP2 supercomputer using the 3-D Richtmyer-Meshkov compressible turbulence kernel demonstrates the effectiveness of the runtime engine in improving SAMR scalability. [ABSTRACT FROM AUTHOR]

An in-plane load measuring technique is developed to perform the strength test of the micro-cantilever. Based on electromagnetism theorem, Micro UTM (Universal Testing Machine) was in-house made with the load range ±1 N and the displacement range ±300 µm. It applies an in-plane load on the free-end of the micro-cantilever. The load acts as a bending moment for the root of the cantilever, but as a torque for the anchor. The results show that for samples with different sizes the ultimate loads range from 1.3 to 69.8 mN and the calculated torque is approximately proportional to the square of the bonding length. Two failure modes, fracture at the root of the cantilever and fracture at the anchor, are observed by micro examination to the debris, which indicates that there is a critical design to achieve the strength balance between the cantilever and the anchor. The work demonstrates that Micro UTM is a powerful instrument for the strength test of the micro-cantilever and similar micro-structures. [ABSTRACT FROM AUTHOR]

This paper presents the results from an analytical investigation of the behavior of composite circular cylinders subjected to internal and external surface loading. The present cylinder consists of a number of homogeneous ply groups of axially variable thickness. Each ply group forming a layer is treated as an individual thin elastic cylinder of generally orthotropic material with interfacial stresses on the inner and outer surfaces of the layer as boundary loading. The deformation and stresses in each layer can be expressed in terms of interfacial stresses along the exterior surfaces of each layer. All displacement and stresses throughout the composite cylinder can be determined subsequently after satisfying boundary conditions at the inside and outside surfaces of the cylinder in conjunction with the recurrence relationship among interfacial stresses. Numerical results are presented for different values of the inner-to-outer ratio, number of layers, stacking sequence, axially-variable-thickness parameter, and load factor. Based on the presented results, conclusions can be drawn concerning the cylinder behavior and its sensitivity to different parameter variations. [ABSTRACT FROM AUTHOR]

A procedure is given for estimating the residual working life and calculations are presented on the total fatigue damage to the loaded elements in the pipelines with and without allowance for the effects of the water on the actual number of loading cycles of each type. [ABSTRACT FROM AUTHOR]

The results of practical use of the pilot membrane unit UDVV-500 in a system that allows repeated utilization of hydrogen at metallurgical works are examined. The technical and economic factors are cited for forward-flow conditions of feeding gaseous hydrogen into high-temperature annealing furnaces (with burning of the entire spent hydrogen in torches) as well as for furnace feeding conditions (with a system for repeated utilization of hydrogen). [ABSTRACT FROM AUTHOR]

Characteristics of pump versions with front and rear reducers for pumping I40 oil and water are given. Flexure of the screws and loads on the supports are assessed. It is noted that with respect to screw rigidity and loads on the supports a three-support structure with a front reducer is superior to a structure with a rear reducer. A two-support structure, being inferior in shaft rigidity to a three-support structure, has smaller loads on the supports. [ABSTRACT FROM AUTHOR]

We describe the first stage (1830–1870) of formation of the science of cyclic fatigue of metals closely related to the events of failures of railway transport. In the 1830s, French engineers (J. B. Poncelet, A. Morin, and others) described the phenomenon fatigue. The scientific research into this field was originated in the 1840s in England (W. J. Rankine, H. James, W. Fairbairn, J. E. MacConnel, et al.). However, the first fundamental investigations were carried out in Germany by A. Wöhler. He developed a method and means (machines and devices) for fatigue testing of car axles and specimens and introduced the notions of fatigue limit and the number of cycles to failure as the main characteristics of the fatigue resistance of the metal. As a result of systematic investigations, he accumulated a vast amount of data on the fatigue behavior of metals depending on the loading mode (bending, twisting, or tension), stress ratio, notches, etc. [ABSTRACT FROM AUTHOR]