Evaluation Of Load Carrying Capacity Research Articles

Face gear drives: Nominal contact stress calculation for flank load carrying capacity evaluation

Face gear drives are angular gear units in which an involute pinion meshes with a face gear wheel. Spur and helical face gear drives are possible with or without center offset. Face gear drives can be manufactured on conventional gear cutting machines. Furthermore, the pinion is free to move axially and such displacements have no effect on the contact pattern. This makes them a promising gearing for various applications. Due to the lack of established calculation standards, the design of face gear drives is a challenge and often results in oversizing or early failures. This may also be why face gear drives have not yet established themselves in power transmissions. Instead, the main application can be found in kinematic/auxiliary drives. In this paper, two methods for contact stress calculation for face gear drives with any configuration between helix angle and center offset are developed. Calculation examples compare the two methods and confirm the applicability. Overall, this study provides a new standard-capable easy-to-program calculation method for the contact stress based on existing standards for cylindrical gears.

A time-coupling consideration for evaluation of load carrying capacity in district multi-energy systems

This paper proposes a systematic approach to evaluate the load carrying capability of a district multi-energy system (MES) using the Energy Hub (EH) modeling approach. The EH approach is used to model the system, and the EH steady-state security region concept is introduced as a means of assessing the system's load carrying capacity. To calculate the security region, a multi-parametric programming (MPP) algorithm is proposed, while a standardized matrix modeling approach is utilized to formulate its mathematical representation. To handle the high-dimensional polytope resulting from time coupling, a strategy is employed to approximate the original polytope using a reduced number of lower-dimensional polytopes. These lower-dimensional polytopes are specifically associated with a limited number of time periods, thereby alleviating the computational complexity. The proposed method offers an improved balance between computational accuracy and efficiency compared to existing approaches, while retaining the inherent time coupling characteristics across different period combinations.

Bridge Evaluation Based on Identified Influence Lines and Influence Surfaces: Multiple-Scenario Application

Bridge influence lines (BILs) and bridge influence surfaces (BISs) are inherent static parameters of bridges which can be extracted from moving vehicle-induced bridge responses. Compared with dynamic parameters, these parameters are directly related to the stiffness and internal forces in each cross-section of a bridge therefore can be considered as an effective bridge metamodel. To accelerate the engineering practice of BIL- and BIS-based bridge evaluation, this paper first briefly reviews the current BIL and BIS field test and identification methods. Then, the bridge evaluation guidelines of China and the United States are introduced as the basis of the evaluation methods. Engineering application scenarios for bridge evaluation, including permit load verification, performance degradation checking, and load carrying capacity evaluation, are summarized, and a multiple-scenario bridge evaluation method is established. At the end of this paper, an evaluation example of a four-span continuous bridge is presented to illustrate the application procedure and verify the effectiveness of the proposed method. The outcomes of this paper provide a promising application method of field test BILs and BISs, which may help bridge engineers more effectively use these parameters in engineering practice.

A Load-Carrying Capacity Evaluation Method for the Welded Joints of Rocket Engine Frame

The load-carrying capacities of welded joints need to be paid attention to in the design of the frame, which transfers the thrust generated by the rocket engine to the rocket body. A load-carrying capacity evaluation method of welded joints based on the structural stress method is proposed in this study. Both the ultimate load-carrying capacity and fracture section angle are precisely obtained by the evaluation method. At the same time, a definition of weld-failure stress is given based on the evaluation method and tests. The load-carrying capacity of welded joints in the rocket engine frame is analyzed through the finite element model, including the overall structure and local weld details. The weld-failure stress of welded joints is obtained based on the analysis of three types of welded structures—standard shear specimen, U-shaped fillet welded specimen and pipe-plate fillet welded specimen. The safety factors of the transverse rod and longitudinal bearing rod welded joints of the frame are 8.6 and 13.4, respectively.

Determination of Prestress Losses in Existing Pre-Tensioned Structures Using Bayesian Approach.

Deterioration of materials and structures is an unavoidable fact, and prestressed concrete structures are not an exception. The evaluation of load-carrying capacity and remaining service life includes collecting various information. However, one type of information is essential and the most important, the state of prestressing, which inevitably decreases over time. Currently, many possible methods for the evaluation of prestressing are available. These techniques are part of the structural assessment and provide residual prestressing force value which is later used in the evaluation process. Therefore, it is suitable to provide the value of prestressing force based on certain probabilistic backgrounds. This study addresses the determination of residual prestressing force in pre-tensioned railway sleepers one year after their production, using the so-called Bayesian approach. This technique is focused on the validation of results obtained from the application of the non-destructive indirect saw-cut method. The Bayesian approach considers analytic calculation as the primary method of prestressing determination. In this paper, Monte Carlo simulation was used to determine the total variability that defines all Bayesian systems of probability functions. Specifically, a total of 1000 simulations was applied, and the current random vector of prestressing force derived from the analytical calculation has been assumed as a normally distributed function. Finally, obtained results for different depths of saw-cuts are compared. The results of the experimental and statistical determination of residual prestressing force provide its value with a 95% confidence level. This study suggests that the implementation of the probability approach can be an effective tool for determining prestress losses.

Rapid Evaluation of Load-Carrying Capacity of Long-Span Bridges Using Limited Testing Vehicles

Load testing is usually used to evaluate the load-carrying capacity of long-span bridges in their service life. However, a large number of calibration trucks should be arranged in complicated loading patterns to deform bridges during load testing, which is labor-intensive and time-consuming. Aiming to solve this problem, this paper proposes a rapid bridge load-carrying capacity evaluation method using limited testing vehicles. The methodology includes three steps: influence line identification from limited vehicle exciting responses; influence line correction based on prior information of the bridge; and influence line–based bridge load-carrying capacity evaluation. To apply this method in engineering practice, standardized truck passage routines are designed. An application example involving a 1,280-m long-span suspension bridge is presented at the end of this paper. The truck routines, extracted bridge influence lines, and predicted load-carrying capacity of that bridge are presented based on the proposed methods. The testing results are also compared with standard load testing conducted 12 years ago to evaluate bridge performance changes. The outcomes of this paper provide a workable and economical method for long-span bridge load-carrying capacity evaluation.

Buckling in prestressed stayed beam–columns and intelligent evaluation

For prestressed stayed beam–columns, the buckling behaviour is studied analytically, and the intelligent models for evaluating the nonlinear behaviour are developed using machine learning. An implicit solution, which allows the direct evaluation for the buckling behaviour of both doubly-symmetric and mono-symmetric stayed members, is determined analytically for the first time, and an explicit simplified solution of the buckling load is obtained using regression. Both the implicit and explicit solutions can simplify the traditional numerical method for evaluating the buckling load of stayed members, and they are verified using numerical modelling and excellent comparisons are obtained. Based on the explicit solution of the buckling load, machine learning models are adopted to develop the intelligent methods for evaluating the nonlinear buckling behaviour of prestressed stayed beam–columns, which can overcome the difficulties in distinguishing between pure and interactive buckling modes in the traditional method for load-carrying capacity evaluation. The results in the test set show that Extreme Gradient Boosting (XGBoost) and Artificial Neural Network (ANN) can predict the nonlinear failure mode and ultimate load of prestressed stayed beam–columns accurately and reliably.

Load-carrying capacity evaluation of girder bridge using moving vehicle

Efficient and reliable load-carrying capacity evaluation of deficient bridges is essential for bridge maintenance and management. Based on load-carrying capacity evaluation of an existing bridge, operator can formulate strategies and implement countermeasures such as repair, strengthening or traffic regulation. Currently, static load test is used widely for evaluation of bridge load-carrying capacity. The test, however, is often considered expensive and requires massive traffic closure that hinders frequent implementation on highway or bridges in the rural area. In this paper, an efficient method for load-carrying capacity evaluation of girder bridges based on displacement under moving vehicle is proposed. The method consists of three main procedures, namely, radar-based dynamic displacement measurement under truck pass-by test, influence line extraction, and estimation of the displacement under the static load test scenario. Based on these procedures, evaluation of load-carrying capacity is conducted following the AASHTO manual. The method was verified in numerical simulations using three-dimensional finite element model of typical girder bridge under vehicle loading. Effects of vehicle weight, vehicle speed, and road roughness on the accuracy of displacement estimation were investigated in the numerical simulations. Full-scale implementation of the method was conducted on a simply supported prestressed concrete girder bridge to investigate feasibility of the proposed method and to provide guidance for practical application. The results reveal that load rating factor of the girders can be reliably evaluated. The evaluation process was also more effective and economical than the conventional method.

Fracture studies on carbon steel straight pipes having off-centred circumferential through-wall crack under finite compliance

The level-3 Leak-Before-Break (LBB) assessment of nuclear piping system is based on simplified fracture mechanics calculations. A postulated through-wall circumferential crack is shown to be stable even under extreme loading conditions. An important aspect of this fracture assessment, which is generally not considered, is the reduction in load at the cracked section that occurs due to the local and global compliance of the piping system. In this study, the effect of piping system compliance, crack size and crack location on the load carrying capacity of SA-333 Gr. 6 carbon steel pipes was analysed. Experimental investigations were performed on 8״ NB Schedule 100 pipes (Outer diameter 219 mm and wall thickness of approx. 12.6 mm) under quasi-static four point bending loads. Out of the six fracture tests, one specimen had a through-wall circumferential crack at the centre (along the length of pipe) and the remaining five tests had off-centred cracks. While the initial crack size showed a weak influence on the load carrying capacity of a stiff piping system, the effect of crack location was, however, quite significant. Calculations based on twice-elastic slope (TES) method and limit analysis of uncracked piping system (in some cases) for evaluation of load carrying capacity of pipes under finite compliance may lead to large safety margins.

支間部に腐食劣化の生じた鋼 I 桁橋の耐荷性能評価に関する解析的検討

支間部に腐食劣化の生じた鋼 I 桁橋の耐荷性能評価に関する解析的検討

Modeling of shear mechanisms and strength of concrete deep beams reinforced with FRP bars

With the growing application of concrete structures reinforced with fiber reinforced polymer (FRP) composite materials, it is necessary to develop more rational mechanical models for their load-carrying capacity evaluation. Firstly, this study numerically analyzed the influences of differences in bond behavior and axial stiffness between FRP and steel bars on the shear behavior of concrete deep beams. It was identified the reinforcement stiffness is the main influencing factor, and an explanation on how the reinforcement stiffness influences the shear performance of deep beams at the mechanism-level was also provided. On this basis, a mechanical cracking strut-and-tie model (CSTM), which theoretically considered the effect of the critical shear crack on the diagonal strut capacity, was proposed to predict shear mechanisms and strength of concrete deep beams reinforced with FRP bars. The proposed CSTM was verified by a shear database of 52 existing tests and compared with predictions of other models. In addition, for purpose of practical design, a simplified CSTM was proposed and verified to be superior to the shear models of CSA S086-12 and ACI 440.1R-15 in terms of safety margin and accuracy.

A Research on Access of Load Carrying Capacity of Large Diameter Piles

The evaluation of load carrying capacity of piles needs the geotechnical properties, penetration tests, the nature of the subsoil both around and beneath the proposed pile, adequate description of rock to convey its physical behavior on borings, dead loads, live loads dimensions of the piles (length and diameter of pile). To compare the length and diameter response of bored cast in situ piles, the data required is obtained from the site of project name Four Laning Project of Nagpur-Saoner-Betul Section of NH-69. The subsoil profile of site shows the clayey and silty clayey soils at the top to the considerable depth underlying highly weathered sandstone. The water table is observed from 4.5 m below the ground level. Here it is not possible to provide shallow, raft foundation as the soil strata mostly clayey and silty clayey soils which have very less safe load bearing capacity. Hence deep foundation proposed for the work. Sufficient number of borings taken in accordance with IS: 1892. Study is done by using all these geotechnical engineering properties at all bore holes locations, varying length and diameters of piles for evaluation of load carrying capacities as per IS:2911 (Part 2) and IRC:78. The load carrying capacity for different diameter of piles and for different length of piles goes on increasing with the increase in diameter. The contribution of end bearing resistance increases up to 170%, whereas contribution of frictional resistance increases up to 40%. Theoretical settlement for different diameters of piles for 25m length of pile has been computed. It has been observed that the theoretical settlement for 1.2 m diameter pile for 25 m length of pile is found to be more than actual settlement obtained from pile test for the same dimensions of the pile. Since theoretical settlement prediction is within in permissible limit and greater than the settlement obtained from the actual pile load test data, the load – settlement designed using excel can be used by the geotechnical engineers for prediction of the load and settlement calculations.

CFD 해석을 이용한 배관지지용 유압식 완충기의 밸브 스프링 설계 및 지지하중 평가

CFD 해석을 이용한 배관지지용 유압식 완충기의 밸브 스프링 설계 및 지지하중 평가

Bridge influence line identification based on adaptive B‐spline basis dictionary and sparse regularization

Bridge influence line (BIL) is a promising tool for the real applications in the fields of bridge weight-in-motion (BWIM), model updating, damage identification, and load carrying capacity evaluation. The key of such applications is how to obtain the accurate results of BIL. To accurately identify BIL based on bridge dynamic responses induced by a moving vehicle, two critical problems, including how to construct a general representation function of BIL and how to deal with the ill-posed inverse problem, should be properly resolved. This paper proposes a novel approach based on the adaptive B-spline basis dictionary and sparse regularization technique for BIL identification. A representation of basis function is first established to construct BIL, and then integrated with a redundant B-spline basis dictionary to ensure the sparsity of solution. A curvature-based adaptive node optimization method is proposed to automatically adjust the spatial arrangement of nodes according to the shape of BILs. Numerical and experimental validations are conducted to verify the accuracy and robustness of the proposed approach. The identified BIL results are accurate, indicating that the proposed node-adaptive optimization and sparse regularization techniques are effective to improve the quality of BIL identification. It is also shown that the proposed approach is not sensitive to the noise interference and configuration of testing vehicle. Through the robustness testing, it is proved that the proposed approach has the merits of high accuracy and strong robustness.

The stress property analysis and evaluation of load carrying capacity of hollow slab bridge with missing thickness of upper floor plate

The stress property analysis and evaluation of load carrying capacity of hollow slab bridge with missing thickness of upper floor plate

Analysis of Appropriateness for Maintenance of Aged Small Bridges based on Condition and Load Carrying Capacity Evaluation

현재 시설물 안전 및 유지관리에 관한 특별법에 의하면 소규모 교량은 육안점검 위주의 정기점검만 실시하고 있다. 특히 공용년수 30년 이상의 교량은 노후화에 따라 개축여부에 관한 의사결정이 필요하지만 외관상태만으로 결정해야 하는 상황이 발생하여 안전적인 유지관리의 측면에서 미흡한 부분이 있다. 본 논문에서는...

Evaluation of load-carrying capacity of full-scale falling protection net using distinct element method

This article presents a simulation of a full-scale falling protection net using three-dimensional distinct element method. First, an application of distinct element method utilized cylinder rigid body element for collision response analysis of a flexible structure that has a long and slender shape similar to wire rope. Second, contact spring normally obtain contact force between the cylindrical element and spherical element in the case of distinct element method. However, connect spring that expresses axial stiffness like tension or compression and bending stiffness of the flexible structure was indicated as a fresh approach of the analysis method. Third, it is suggested to simulate large deformation program using connect spring of three-dimensional distinct element method and examine the application of reproducibility to analyze a full-scale falling protection net. Finally, the analysis result evaluated the performance of falling protection net using distinct element method which utilized connect spring and cylindrical model.

Evaluation of the horizontal load-carrying capacity of a thin steel bridge pier by means of the Damage Subloading Surface model

The evaluation of the load-carrying capacity of a structure is an important aspect of the structural design. In particular, large seismic events can significantly compromise the performances of structures, or parts of them, due to the formation and accumulation of plastic deformation. In the present paper, we analyse the seismic performance of a thin steel bridge column by means of an unconventional elastoplastic and damage model. The idea is to evaluate the horizontal load-carrying capacity of the pier for different seismic events, analysing the conditions that can compromise the stability of the structure.

Current Status of Degraded Road Bridge Slab Located in Mountainous Area

In the mountainous area of the Hokuriku region, bridges are suffering early deterioration caused by salt damage, alkali-silica reaction (ASR) and frost damage. Under such a regional situation, the load carrying capacity evaluation of these bridges has become an urgent issue. In this study, a statistical method–survival analysis–was carried out by using inspection data for bridges in the Hokuriku region, and the relationship between degradation tendency of bridges and regional characteristics causing salt damage, ASR and frost damage has been studied. In addition, the degradation causes of the reinforced concrete deck of a road bridge which deteriorated early in the mountainous area of the Hokuriku region were investigated. Cylindrical core extraction was carried out to analyze the degradation causes. Polarizing microscopic observation of specimens collected from RC slabs confirmed that cracks developed from the andesite particles and cracks were confirmed to be filled with ASR gels. Therefore, ASR was a cause of the deterioration. Moreover, the degradation in the mechanical properties of concrete due to ASR was also studied and reported. The results show that the reduction in compressive strength and static elastic modulus of both dry and leakage-water parts affected the load bearing capacity of the structure.

A Study of Structural Behavior Rationality and Load Carrying-capacity Evaluation of Integral Abutment Bridge

A Study of Structural Behavior Rationality and Load Carrying-capacity Evaluation of Integral Abutment Bridge