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Betonarme yapı ve yapı elemanları, kullanım süreleri boyunca çevresel faktörler, uygun olmayankullanım, deprem etkisi gibi çeşitli yük etkilerine maruz kalırlar. Düşük malzeme dayanımı ve kalitesiyapının taşıma gücünü azaltan en önemli faktördür ve diğer etkenlerle birlikte değerlendirildiğinde yapıve yapı elemanlarında hasar oluşumunun en önemli nedenidir. Bu nedenle yapıların performansının hasardüzeylerine göre belirlenmesi ve uygulanacak onarım/güçlendirme yöntemine karar verilebilmesi içinmevcut malzemelerin kalitesinin belirlenmesi ile birlikte bir ön tasarım çalışması yapılmasıgerekmektedir.Çalışmanın en önemli adımlarından birisi, yapının tamamının ya da belirli bir bölümünün sayısalmodelinin hazırlanması işlemidir. Hassas bir sayısal model oluşturmak için malzemelere ait bünyeselbağıntılar ile elemanların bireysel davranışının gerçekçi bir şekilde tanımlanması gerekmektedir. Buçalışmada sonlu elemanlar modelinin deneysel sonuçlara olan uygunluğu araştırılmıştır. Bu amaçlayazarların daha önce deneysel çalışmalarını gerçekleştirdikleri yalın ve güçlendirilmiş betonarme kirişlerile literatürde betonarme kirişler için yapılan deneysel çalışmaların modellemesi sonlu elemanlar yöntemiile yapılarak elde edilen sonuçlar deneylerden elde edilen sonuçlarla karşılaştırılmıştır. Araştırmacılar,daha önce yığma duvarların sayısal modellenmesinde kullandıkları elasto-plastik hasar teorisi yaklaşımınıbetonarme kirişler için geliştirerek uyarlamışlardır. Çalışmada LUSAS sonlu elemanlar yazılımıkullanılarak iki adet yalın ve üç adet Lifli Polimer (LP) sargılı kirişlerin eğilme altındaki davranışlarıbaşarı ile modellenmiştir., Reinforced concrete structures and structural elements are subjected to various load effectsduring their lifetime, such as environmental factors, improper handling, earthquake effects. Low materialstrength and low quality are the most important factors that reduce the load carrying capacity and whenevaluated together with other factors, it is the most important cause of damage to the structures andstructural elements. Therefore, in order to determine the performance of the structures according to thedamage levels and decide on the repair / strengthening method to be applied, a preliminary design studyhas to be done with determining the quality of the existing materials. One of the most important steps ofthis work is to prepare the numerical model of a complete structure or a specific part of the structure. Inorder to develop a precise numerical model, it is necessary to define the behavior of the elements with theconstitutive relations of the materials realistically. In this study, the numerical models of the reinforcedconcrete beams which authors had already performed the experiments and reinforced concrete beamssubjected to experimental loads in the literature are modelled and the results are presented. Researchersadopted the approach of elasto-plastic damage theory for reinforced concrete beams previously used inthe numerical modeling of masonry walls. In this study, the flexural behavior of two unreinforced andthree Fiber-reinforced polymer (FRP) strengthened beams with using LUSAS finite element softwaresuccessfully modeled.

This article presents numerical finite element method (FEM) analysis of the stress concentration at toes and crack-like faults in load-carrying fillet welded cruciform joints with transversal slits resulting from non-fused root faces. Potential fatigue damage of such joints subjected to cyclic tensile and bending loads appears in the form of fatigue cracks starting from the weld roots or toes. The aim of this article is to find qualitative and quantitative relationships between geometrical parameters of the load-carrying fillet welded cruciform joint subjected to tensile and bending loads and the stress concentration at weld toes and roots. The results of the analysis represented by the stress concentration factors (SCFs) and the stress intensity factors KI and KII are shown in the form of tables, graphs and mathematical formulas, which may be applied for fatigue assessment of such joints.

In this study, considering the combined effects of the load carrying capacity of broken fibers and its evolution with temperature, a theoretical model for characterizing ultimate tensile strength of unidirectional ceramic-fiber reinforced ceramic composites (UCFRCCs) as a function of temperature is established. The model is verified by comparison with measurements available of temperature dependent ultimate tensile strength of UCFRCCs. Besides, on the basis of the established model, the quantitative influences of broken fibers and fiber Young's modulus on the ultimate tensile strength as a function of temperature are analyzed. The results show that the volume fraction of broken fibers and its strength contribution ratio at different temperatures are almost proportional to each other. Besides, the improvement of fiber Young's modulus at high temperatures is more conducive to enhancing the ultimate tensile strength of UCFRCCs. This study not only provides a powerful means to characterize the ultimate tensile strength, but also contributes to providing theoretical basis and guidance for the design and fabrication of UCFRCCs at various temperatures.

This study comprises experimental tests that consist of 138 tests that are divided as follows: 36 tests for single pile, 36 tests for pile group (2 × 1), 36 tests for pile group (2 × 2) and 30 test...

This paper presents the evaluation and analysis of LWC) manufacturing and applications. Clear comparisons of different LWC types according to the physical specifications and properties lead to accurate selection of concrete type depending on the conditions surrounding the buildings projects. The widely used of LWC in all over the world is approaching researchers to seriously consider finding new techniques to produce more resistant varieties nearby conditions of construction projects. The LWC types are more sustainable than burnt brick due to its providing high densities and better insulation. This work has been carried out the deep discussion and comparison between the properties of fly ash, AAC and CLC concrete types. The advantage of aerated lightweight concrete compared with traditional concrete is present in advance strength to weight ration, less thermal expansion coefficient and high insulation of sound. The classified of aerated lightweight concrete into foamed and autoclaved concrete has attention in the suggested mixture. By maintain the density as constant parameter, their load carrying capacity in compression, water absorption and thermal insulation are to be tabulated and concluded by their performance.

In this paper, a simple but feasible approach is proposed to predict the time-dependent load carrying behaviours of jacked piles from CPTu measurements. The corrected cone resistance, which considers the unequal area of the cone rod and the cone, is used to determine the soil parameters used in the proposed approach. The pile installation effects on the changes in the stress state of the surrounding soil are assessed by an analytical solution to undrained expansion of a cylindrical cavity in K0-consolidated anisotropic clayey soil. Considering the similarity and scale effects between the piezocone and the pile, the CPTu measurements are properly incorporated in the shaft and end resistance factors as well as in the load-transfer curves to predict the time-dependent load carrying behaviours of the pile. Centrifuge model tests are conducted and the measured load carrying behaviours of the model piles are compared with the predictions to validate the proposed approach. The proposed approach not only greatly saves the time of conducting time-consuming pile load tests, but also effectively avoids solving the complex partial differential equations involved in the consolidation analysis, and hence is feasible enough to determine the time-dependent load carrying behaviours of jacked piles in clay.

Composite cross joints are common structures in an airframe. When this type of joint is used on an air inlet stiffened structure, it will undertake large bending moment, especially under overpressure of the engine. In this paper, two types of cross joints are tested experimentally and simulated to investigate the load bearing characteristics and make comparative remarks. Four-point bending tests are conducted and the load deflection curves are obtained; besides, the damage pattern of the joints is reported. Based on composite progressive damage model, the numerical simulations have a good agreement with experimental results, revealing the joint failure mechanism and fastener force feature of various joints. The comparative assessment of two types of joints is summarized.

The Author presents the method that taking account an influence of surface roughness on both flow and operating parameters of a slide journal bearing in the paper. For this purpose, the expected value for the gap height function should be determined. The expected value is then the most probable value of the height of the lubrication gap. There are presented the results of analytical and numerical calculations of flow and operating parameters in slide journal bearings. Numerical calculations were performed using the finite difference method as well as own calculation procedures and the Mathcad 15 software.

In this paper, a finite element model with girth weld defects considering crack tip singularity was established in order to facilitate the accurate and rapid safety assessment on girth weld defects of long distance gas Transmission pipeline. Then the J-integral of girth weld cracks in pipes with different defect sizes was calculated, and the influence of weld matching coefficient and material hardening index on J-integral is analyzed. Furthermore, the influence factors of limit load of pipeline with girth weld defects based on J-integral theory are studied. Based on this, the engineering calculation formula which can calculate J-integral and limit load rapidly in the situations with specific matching coefficient and material hardening index was proposed. And the following research results were obtained. First, the engineering calculation formula based on the fitting of finite element calculation results has high accuracy, which can calculate the J-integral of defects in a large geometric range and the limit load of pipelines with girth weld cracks. Second, the J-integral of cracks in pipes with girth weld defects is closely related to defect size, material properties and weld matching coefficient, and the limit load of pipes with defects decreases as the crack size increases and increases as the material hardening index increases. Third, for the X80 pipes with surface cracks at the centerline of the girth weld, the load carrying capacity of the pipes with low-strength matched weld are lower than that with high-strength or equivalent-matched weld. In conclusion, the research results can be used as reference for the safety evaluation and integrity management of in-service gas pipelines. Keywords: X80 gas pipeline, Girth weld defect, J-integral, Limit load, Safety assessment

In robotic assistive devices, the determination of required assistance is vital for proper functioning of assistive control. This paper presents a novel solution to measure conveniently and accurately carried payload in order to estimate the required assistance level. The payload is estimated using upper armforcemyography (FMG) through a sensor band made of force sensitive resistors. The sensor band is worn on the upper arm and is able to measure the change of normal force applied due to muscle contraction. The readings of the sensor band are processed using support vector machine (SVM) regression techniqueto estimate the payload. The developed method was tested on human subjects, carrying a payload. Experiments were further conducted on an upper-body exoskeleton to provide the required assistance. The results show that the developed method is able to estimate the load carrying status, which can beused in exoskeleton control to provide effectively physical assistance needed. In robotic assistive devices, the determination of required assistance is vital for proper functioning of assistive control. This paper presents a novel solution to measure conveniently and accurately carried payload in order to estimate the required assistance level. The payload is estimated using upper arm forcemyography (FMG) through a sensor band made of force sensitive resistors. The sensor band is worn on the upper arm and is able to measure the change of normal force applied due to muscle contraction. The readings of the sensor band are processed using support vector machine (SVM) regression technique to estimate the payload. The developed method was tested on human subjects, carrying a payload. Experiments were further conducted on an upper-body exoskeleton to provide the required assistance. The results show that the developed method is able to estimate the load carrying status, which can be used in exoskeleton control to provide effectively physical assistance needed.

The aim of this study is to investigate behavior of reinforced concrete beams with insufficient flexural strength which are reinforced by ultra high performance concrete (UHPC) were examined experimentally. UYPC with 3% fiber volume was used for manufacturing laminates which will be used for reinforcing. UHPC having three different thickness (30 mm, 50 mm and 70 mm) where one of them will be control sample was used for observing effect of change in thickness over flexural behavior were manufactured and applied over reinforced concrete beams. RC Beams were tested under four -point bending loads. Increase in load carrying capacity varying with 20%-58% rates were obtained in samples which were reinforced with UHPC.

U-shaped straps are an effective means to postpone premature debonding failure when fiber-reinforced polymer (FRP) composites are applied in structures. However, the U-wrap anchors are not cost-effective and in many cases cannot completely prevent the debonding phenomenon. In the current study, an innovative technique named “warp and woof strap” (WWS) is introduced for anchoring longitudinal FRP sheets, in which some parts of FRP fibers are manually made bi-directionally. Unlike the conventional U-shaped anchors, the anchorage system in this method is in direct contact with the tension side of the beam. Totally, 20 reinforced concrete (RC) beams, 120 × 160 × 1400 mm in size, were subjected to the four-point loading to evaluate the efficiency of the introduced anchorage system in comparison to the U-shaped anchorage. The effect of different parameters including the method employed for anchoring the longitudinal carbon fiber reinforced polymer (CFRP) sheet, anchorage height and width, location of FRP anchorage application, use of the corner strip and rounding corner method, and configuration of WWS anchorage were investigated. The experimental results indicated that the efficiency of the WWS method in preventing undesired debonding mode of failure is much better than that of conventional U-shaped anchor. It was also observed that using WWS method can improve the load carrying capacity and ductility up to 32% and 80%, respectively, compared to U-shaped anchors.

Background Asymmetrical load-carrying while walking requires modifications in joint forces to compensate the extra mass and ensure body stability, particularly when the environment is uneven, such as with a curb. Carrying a bag with one hand (dominant or non-dominant) may constrain the movement of the arm, altering the interlimb coordination of the upper limbs. Prior studies did not show changes in interlimb coordination when a light load was attached to the wrist, but the use of a bag to carry the load can be potentially disturbing since exaggerated movements of the bags may compromise balance. In this case, changes in interlimb coordination would be expected to minimize bag movements. However, it is not clear if these changes in interlimb coordination would be sufficient to affect the curb negotiation task. Research question We investigated the effect of asymmetric load-carrying using different bag types with the dominant and non-dominant hands on upper limb coordination and walking adaptations in a curb negotiation task in young adults. Methods Seventeen young adults walked and stepped down a curb while carrying a bag with 7% of their body mass. The experimental conditions were to walk without the bag, carrying the bag (with and without strap) using the dominant and non-dominant hand. Results Carrying the bag reduced the anti-phase pattern and increased the right or left shoulder phases, depending on the side used to carry the bag. It means that the limb that carried the load almost did not move while stepping down the curb. Load transportation did not influence foot-curb negotiation variables. Significance Our study indicates that a mild load and the bag influenced the interlimb coordination of the upper limbs. Despite that, young adults compensated for the disturbance caused by the load carriage and did not compromise the curb negotiation task.

Approximately, 65% of the existing residential structures are adjacent in Turkey. In addition to the social disadvantages of living in adjacent buildings, these structures are prone to pounding during earthquakes and they are under threat during the construction and demolition of the neighboring structures. The neighboring structures may experience damage during/after the demolition of adjacent structures due to pounding of structural components. There are many cases of casualties and economic losses due to the collapse of neighboring structures during the demolition of old structures. The damage can be occurred as a result of constructing shared foundations, different foundation depths, the groundwater level, and possible impact of the work machine during demolition. Also, in areas with high seismic risk, there is a possibility of an earthquake at a time between the demolition and reconstruction stages of a building, which can cause significant damage. Due to these reasons, the design and construction stages of adjacent structures should be described by building codes in detail. In order to renew the adjacent structures at different times, horizontal support elements should be used and required design calculations should be made. This study examines the truss system applications as horizontal support in such structures built in Eskisehir. The characteristics of the section and system properties, the horizontal load carrying capacity, the choice of support zones between the adjacent structures, and the characteristics of strain deformation are determined. It is concluded that the horizontal support applications prevent horizontal forces due to earthquakes and various vibrations in neighboring structures and prevent structural deformation.

This paper provides detailed design and characterisation of the Pneumatic Muscle Actuator (PMA) proposed for actuating an artificial human arm. The anatomy and the load carrying capacity of the human arm are considered for designing the PMA. The PMA is fabricated using the braided sleeve and latex tubes, and a pneumatic circuit is designed for its characterisation. The proposed artificial human arm with PMA can be used as a teaching aid to simulate neurological disorders.

In this work, the role of steel reinforcement in under reinforced concrete beams when subjected to flexural fatigue loading is studied using the acoustic emission (AE) technique. Three-point bend notched beams of three different sizes and with varying reinforcement ratios are subjected to step-wise increasing variable amplitude fatigue loading. The crack mouth opening displacement (CMOD) and AE parameters are analyzed to study the evolution of damage, load carrying and failure mechanisms in under reinforced concrete beams. It is concluded that the presence of reinforcement substantially increases the fatigue life. Further, the CMOD could be used as a criterion for failure in reinforced concrete beams under fatigue loading.

The behaviour of prestressed stayed steel columns under axial compression has been intensively investigated; however, research on their behaviour under eccentric loading has not been conducted. This current work investigates the stability behaviour of prestressed stayed steel box section columns under eccentric loading by using finite element analysis. It was demonstrated that the load carrying capacity could be decreased by the load eccentricity. A reduction factor that quantitatively denotes the effect of load eccentricity on the load carrying capacities was defined, and approximate formulae calculating the reduction factor have also been proposed. Further, it has been found that the effect of eccentricity on the load carrying capacity is significantly affected by the critical buckling modes of prestressed stayed steel columns. In addition, the effects of slenderness ratio, crossarm length, and stay diameter have also been presented in this work. The results will be of great assistance when designing this type of column under eccentric loading.

Problem statement. Correct assessment of load carrying capacity of connections is crucial for ensuring the structure reliability. The initial parameter for the calculation of load carrying capacity of the timber structures connections is the characteristic embedment strength (the strength of timber massive under dowel penetration). This characteristic can be determined using empiric formulas or through standard experimental investigation. Currently a wide database on the results of the experimental assessment of stress-strain state of timber structures connections exists, which covers the questions of determination of failure patterns, failure load, strength, “load-deformation” dependences etc. Nevertheless, a combination of the standard investigation methods with non-standard techniques allows obtaining more detailed information about the interaction between elements of the connection. The registration of the displacement fields of the surface or volume of the element is possible using optical physics methods, e.g. laser holographic interferometry. The purpose of the article is to investigate the strength and peculiarities of the deformation of timber under the influence of metal dowel using laser holographic interferometry method. Conclusion. As a result of experimental investigations, load-displacement curves, failure loads and maximum displacements were obtained for the samples tested. At each loading stage, interferograms were recorded and three-dimensional graphs of the deformed surface of the sample were obtained, which clearly represent the nature and evolution of the interaction between dowel and timber. The resulting complex of data on the deformation and strength characteristics in further studies will be used to develop and verify the design model of the dowel connection of timber elements taking into account nonlinear work.

The use of repurposed railroad flatcars (RRFCs) is an attractive option for low-volume applications due to their modular nature. Further, RRFCs are a sustainable and economical solution for low-volume bridges while providing considerable strength. A limited number of research projects focusing on the development of guidelines to load rate highway bridges constructed out of RRFCs have been conducted in the past. The authors have performed experimental and numerical research on various RRFC bridge configurations to develop guidelines. RRFCs are generally classified as fracture critical members (FCM) since these bridges are comprised of only two cars in the cross section in most cases. Classifying RRFCs as FCMs leads to issues when load rating these bridges, which requires rigorous hands-on inspection every 24-months as per the governing codes that significantly increases the long-term cost. The authors have previously presented the results of laboratory testing of bridges built using RRFCs having fractured primary load carrying component of the one and then both RRFCs. This paper presents a numerical parametric study performed using nonlinear finite element models benchmarked to the previously tested RRFC bridges. The results from both the experimental and numerical studies demonstrated that if certain requirements are met (e.g., utilizing composite concrete decks), RRFCs have adequate reserve strength even in a severely faulted state and need not be classified as FCMs. Additionally, simplified methods have been developed based on the research to assess if a given bridge will meet these criteria which are readily implementable in a typical design office.

Crushed Concrete Debris (CCD) is one of the waste materials, produced during the demolition of any existing structure, which needs to be taken care of and utilized in one or another civil engineering projects. This study represents the experimental results of model plate load tests on footings resting on CCD mixed with sand (CCD-S) composite overlying sand both with and without the inclusion of non-woven geotextile at the interface of CCD-S composite and the underlying sand. Proctor tests were conducted by varying the percentage of sand from 10% to 50% (by weight) with 10% increments. The mix with maximum of maximum dry unit weight has been selected for model plate load tests. Moreover, large box direct shear tests were carried out in order to understand the stress-strain behavior of the selected CCD-S composite. CCD-S composite layer, when placed over sand not only increases the ultimate bearing capacity but also reduces the corresponding settlement of the footing. From the test results, it has been confirmed that CCD-S composite can be deployed under foundations as one of the sustainable materials.

In steel I beams the corrugated webs are sometimes used as an alternative to plain web in many steel construction. The idea behind this concept is an increase in the shear capacity of steel beams without providing the transverse stiffeners. The recent development in steel construction is the used of web openings for the utilization of various technical utilities in web. This paper presents an extensive parametric study on the steel beam with corrugated web having openings in the web. The objective of the present study is to observe the structural performance of this special type of beam towards the strength capacities. In the parametric study 60 models of steel beams with trapezoidally corrugated web with opening has been analyzed by finite element analysis using ANSYS v12. The variables in the present study are angle of corrugation, thickness of web and diameter of opening. The angle of corrugation, web thickness and diameter of web openings considered in the study are 0°, 30°, 45° and 3 mm, 4 mm, 5 mm and 0.5, 0.6, 0.75 times the overall depth of beam, respectively. The parametric study shows that lesser the angle of web corrugation, the more increase in the load carrying capacity is obtained. Ultimate strength capacity of 30° corrugated web beam with different diameter of opening such as 0.5 D, 0.6 D, and 0.75 D is found to be 15.27%, 14.83%, 9.72%, which is more than the beam with plain web. The height to thickness (h/tw) ratio considered in the study are 30, 37.5, 40, 50, and 66.67, respectively. The height to thickness (h/tw) ratio is found to be the main parameter influencing the buckling behaviour of steel beam with corrugated web.

The load-carrying capacity of a K-type joint inside a floor truss is studied both experimentally and numerically. The joint tested is a scaled-down, isolated joint. The tubular braces, plate chord, and division plate are made of SSAB Domex steel. Comparison of load displacement curves received by finite element analyses with curves obtained from tests confirms that numerical models describe joint behaviour reasonable. The paper demonstrates that joints with high load-bearing capacity can be investigated experimentally by scaling the dimensions of the joint down when testing devices can affect the required capacity of the joint. The results presented can also be used for optimizing failure mechanism of similar joints in practice.

A framework to model timber connections at normal temperature and in fire, based on combined finite-element (FE) heat-transfer analyses and temperature-dependent Johansen-type load-carrying models, was developed and applied in a parametric study of previously tested beam-to-column steel-to-timber dowelled connections. Comparison with experimental results shows that the FE heat transfer models provide good estimates of measured temperatures and the load-carrying model gives good approximations of the load-carrying capacity at normal temperature (for dowel and embedment failures) and under standard fire exposure. For the degrees of utilisation expected in fire E fi / R 20 ≈ 0.3 , the developed models are able to predict the failure mode of each dowel and the expected load-carrying capacity. Simulation results showed a clear influence of the thickness of the side members on the fire resistance of the analysed connections. The influence of dowel spacing is not so clear, as it also depends on the dowel diameter. A smaller dowel diameter seems to slightly improve the fire resistance, namely for smaller degrees of utilisation or thinner side members, but compromises the load carrying capacity at normal temperature.

Resilient systems have the capability to survive and recover from seriously affecting events. Resilience engineering already is established for socio-economic organisations and extended network-like structures e. g. supply systems like power grids. Transferring the known principles and concepts used in these disciplines enables engineering resilient load-carrying systems and subsystems, too. Unexpected load conditions or component damages are summarised as disruptions caused by nesciense that may cause damages to the system or even system breakdowns. Disruptions caused by nescience can be controlled by analysing the resilience characteristics and synthesising resilient load-carrying systems. This paper contributes to a development methodology for resilient load-carrying systems by presenting a resilience applications model to support engineers analysing system resilience characteristics and behaviour. Further a concept of a systematically structured solution catalogue is provided that can be used for the classification of measures to realise resilience functions depending on system adaptivity and disruption progress. The resilience characteristics are illustrated by 3 examples.

The pullout load carrying behavior of helical anchors for inclined loading conditions was investigated based on the coupled Eulerian-Lagrangian (CEL) analyses. Various types of helical anchors, specified as Types 1 to 6, were adopted in the analyses. Types 1, 2 and 3 represent those with one, two, and three equal-diameter helical plates and Type 4 was a helical anchor type with two helical plates of different diameters. Types 5 and 6 were both with three helical plates of different diameters in opposite diameter configurations. Inclined loading conditions affected the pullout capacity (Qu) of helical anchors producing lower Qu with increasing load inclination. The patterns of the Qu decrease with increasing load inclination were similar for all helical anchor types considered in this study. The values of Qu were approximately similar up to θ = 60° and then decreased continually with furthering increasing θ. Qu was lowest at θ = 90°. The top-down increasing diameter configuration of helical plates was more efficient than the bottom-up increasing diameter configuration. A normalized load capacity relationship was proposed, which can be used to evaluate Qu for inclined loading conditions. The pullout behavior of helical anchors was governed by helical plates with marked effects of helical plate configuration, which was however less pronounced with increasing θ.

Background A load carrying task was identified as a major factor leading to slip and fall injuries such as overexertion and bodily reaction. Holding a load in front of the body while walking would shift the whole body center-of-mass to the front, loading additional rotational torque at the foot-ground contact. Objectives The present study evaluated if carrying a load would increase the likelihood of slip initiation and the slip severity. Methods Eleven young and 10 older adults participated in the present study. A dry surface or a slippery surface was introduced while walking. Slip distance, peak sliding heel velocity, heel contact velocity, and required coefficient of friction were measured to test the study hypotheses. Results The results showed that significant main effects were found in slip distance, and peak sliding heel velocity and no main effect were found in heel contact velocity and required coefficient of friction. Conclusion In conclusion, younger adults were found to slip longer and faster on the slippery surface while carrying a load. On the contrary, the older adults employed a safety-centered gait adaptation while carrying, to maintain slip initiation and severity characteristics at the same level as normal walking. Furthermore, light load carriage at 10% of body weight was suggested as a safe task for the elderly.

In this article, the effect of prolonged fire (24-hour duration) on reinforced concrete beams made with recycled aggregates from demolished concrete was experimentally investigated. Demolished concrete was used recycled coarse aggregates in equal proportion with natural coarse aggregates. Normal and rich mix concrete with water-cement ratio equal to 0.54 were used. As a control specimen, beams with all-natural aggregates were also cast to compare with the results of the proposed beams. All beams were cured for 28 days and exposed to fire at 1000°C in an oven for 24 hours. After the elapse of this fire period, the beams were allowed to air cool, followed by testing till failure in a universal load testing machine. Comparison of the test results shows that rich mix concrete beams more reduction in flexural strength, more increase in maximum load carrying capacity and deflection than normal mix beams. The maximum reduction in flexural strength was 32.41% for beams cast with 50% RCA and rich mix. Although the fire duration used in this study is rare, yet the outcome provides guidelines for taking proper decisions for retrofitting/strengthening of the fire affected structure before putting it back in service.

A key issue of load-carrying exoskeleton is to maintain the stability of gait during walking and prevent the wearer from falling over. Some of current strategies were to maintain ZMP (zero-moment point) in the support area, which had been widely used in humanoid robot. However, this method would cause serious interference between body and exoskeleton. because the body often gets energy-saving and rapid walking through unstable conditions during human walking. A control strategy for load-carrying exoskeleton was presented in this paper, which maintained the consistency of body ZMP and exoskeleton ZMP. This control strategy could reduce body-exoskeleton interference while maintaining the stability of walking. In this paper, we firstly introduced the experimental environment and the ZMP detection method, and then designed a computational model of the body-exoskeleton interaction force and evaluation criterion for gait stability. Then, a control strategy based on ZMP was designed. Finally, experiments showed that the control strategy could effectively reduce the body-exoskeleton interference, and maintained the stability of wearer’s walking.

Pile foundation is one of the most commonly used foundations for offshore and coastal structures. This paper describes an innovative design for the pile foundation, which institutes an innovative strategy over traditional pile foundation to achieve higher axial bearing capacity. This is achieved by adding restriction plates inside the pile to help form the soil plug. A series of geotechnical centrifuge tests are carried out to evaluate the load bearing behaviors of traditional pile foundation and innovative pile foundation with different types of restriction plates. The pile diameter and shapes of the restriction plates on the soil plug behaviors and pile load carrying capacity are analyzed. The results show that the use of restriction plates could significantly increase the axial bearing capacity of large diameter pile foundations. For different pile diameters, the restriction plates with four smaller holes achieve better performance than those with one large hole of the same effective opening areas. A bearing capacity equation is obtained by normalizing the ultimate bearing capacity with the pile diameters for different restriction plates. This study demonstrates the promise of an innovative pile foundation with a restriction plate as an economic and technically feasible way to produce higher load-bearing capacity to support offshore and coastal structures.

Concrete pipes are widely used in municipal structures and vulnerable to cracking and leakage when subjected to external load. To improve the mechanical properties and hence increase the cracking resistance of the pipe, steel fiber reinforced cement-based composite pipe specimens with steel fibers annularly distributed along the circumferential direction of the pipe were prepared. In the preparation of the annularly aligned steel fiber reinforced cement-based composite (ASFRC) pipe specimens, an external circular magnetic field was applied to the fresh mixture of the steel fiber reinforced cement-based composite to drive the steel fibers rotating to the circumferential direction of the pipe when the mixture was compacted. The three-edge-bearing strength and ductility of the ASFRC and ordinary steel fiber reinforced cement-based composite (SFRC) pipes were tested and compared. The results showed that annularly aligned steel fibers can effectively improve the load carrying capacity and ductility of the pipe specimens, which can be attributed to the higher orientation efficiency factor of the steel fibers and the increase in the number of steel fibers on fractured section of ASFRC pipe specimens.

The subject of this article is the finite element method (FEM) simulation of the multi-layered rectangular composite beam subjected to three-point bending test. The study is focused on the composite beams made of glass or carbon fibre-reinforced laminates (glass fibre-reinforced polymer [GFRP] and carbon fibre-reinforced polymer [CFRP]) for which different laminate stacking were addressed. Three beam geometries with various length-to-thickness ratios included short beam shear (SBS) test, provided the beam is short relative to its thickness, which maximised the induced shear stresses. Simulation included the application of Tsai–Hill, Hoffman, Tsai–Wu, Hashin and Puck failure criteria to perform the composite beam failure analysis wherein the matrix and fibre failure were considered separately. Numerical failure studies also aimed to verify the beam failure modes and the participation of stress tensor elements in material failure.

Medial Tibial Stress Syndrome MTSS is frequently diagnosed as a severe clinical issue which occurs due to the cycle loadings (fatigue failure). Since the mechanical properties of the bones are random variables, therefore, there is a need for a probabilistic approach to rationally assess the reliability level of the fatigue failure of the tibia. The main contribution of this paper is to introduce a novel limit state function to determine the fatigue damage state and the reliability index of MTSS based on the different loading and aging conditions. In this study, the tibias of the several people at the different ages are subjected to the fatigue loadings. The load carrying capacities of the considered specimen are determined based on the reliability analysis. Indeed, several 3D finite element analyses are performed to find out the damage states of the tibias. Accordingly, the reliability-based stress analysis is accomplished to localize the most vulnerable zone of the bone. As it was expected, the higher loading cycles associated with the elder bones is related to the lowest fatigue reliability level. Finally, the target reliability level of MTSS is proposed to deliberate the safe level of the loading condition on the tibia in terms of the walking distance.

The analyses of load carrying capacity of shallow footings, located on semi-infinite horizontal surface, have been dealt at large by various researchers. With the growth in urbanization in the hill...

Cement stabilized soil bases have been used in flexible pavements in Louisiana for years. Soil cement has an excellent load carrying capacity and durability, but is also well-known for developing shrinkage cracks, which can reflect through asphalt concrete surfaces and accelerate the deterioration of asphalt pavements. Micro-cracking is a special reflective cracking mitigation technique used in cement-stabilized base construction. The objectives of the research were to determine the effectiveness and performance of micro-cracking on soil-cement pavements. Micro-cracking was applied on field projects, based on the experience of a previous micro-cracking research project at the Pavement Research Facility of the Louisiana Department of Transportation and Development. Two pavement sites were selected for the field pavement rehabilitation projects, LA 1003 and LA 599, to test the micro-cracking technique. In-situ tests were conducted and pavement performance was monitored for both sites. It was found that an 8.5-in. micro-cracked soil cement pavement showed a similar or better early performance as compared to a non-micro-cracked soil cement pavement with regards to the overall cracking performance. On the other hand, more cracks were found on the micro-cracked test sections than the control sections when micro-cracking was applied on a 12-in. cement treated soil base in Louisiana. Analysis of the structural numbers did not show a significant difference between the control and micro-cracked sections. Further monitoring is recommended for both of the field projects.

Purpose The purpose of this paper is to improve the lubrication performance of a water-lubricated polymer bearing with axial grooves, especially enlarge the minimum film thickness. Design/methodology/approach The bearing diameter is enlarged near the axial ends of the journal, with axial openings of a trumpet shape. A numerical model is developed which considers the proposed trumpet-shaped openings, bush deformation and grooves. The generatrix of the trumpet-shaped opening is assumed to be a paraboloid. Three different variations are covered, and the influences of the trumpet-shaped openings’ parameters on the bearing performance are analyzed. Findings The appropriate trumpet-shaped openings at the axial ends effectively increase the minimum film thickness, and the impact of trumpet-shaped openings on load carrying capacity is very small or even negligible. For the water-lubricated polymer bearing with axial grooves analyzed in this paper, the appropriate trumpet-shaped openings increase the minimum film thickness from 0.53 to 11.14 µm and decrease the load carrying capacity by 2.48 per cent. Practical implications The results of this study can be applied to marine propeller shaft systems and other systems with polymer bearings. Originality/value This paper has presented an approach for significantly increasing the minimum film thickness of a water-lubricated polymer bearing. A study on the performance improvement of water-lubricated polymer bearings with axial grooves is of significant interest to the research community.

A series of innovative connections with the different combinations of steel plates and screws was developed for timber–concrete composite (TCC) system in this paper. Several groups have introduced vulcanized rubber layer to the jointing steel plate, which was used to be glued onto the timber beam surface. Push-out tests were carried out on the proposed connections and three replicates were prepared for each series. The study focused on the load carrying capacity, slip modulus, ductility and the role of some factors of the innovative connections. Moreover, the load-slip behaviour was evaluated based on an existing non-linear model and parametric analysis was also conducted. The research results showed that this connecting system looks suitable for structural application.

In recent years, the superhydrophobic fabrics with specific wetting property had attracted extensive attention of the researcher and industry for their extraordinary performance. In this report, a robust superhydrophobic fabric with oil/water separation property and load carrying capacity had been successfully prepared by introducing the modified magnesium oxide (MgO) and aluminate. It has proved that the modified fabric has excellent stability through tape peeling test, folding test, washing experiment and pH test. In particular, the fabric weight of 200 g could be moved by 22 m on 600 # sandpaper without losing superhydrophobic property. Besides, the fabric can separate oil and water from different oil-water mixtures with a separation efficiency of over 90%, using superhydrophilic-superoleophobic properties. Otherwise, it is 66.8 N/m2 that loadable pressure of the fabric in water. The superhydrophobic fabric has tremendously wide applications in the field of oil-containing wastewater and diving equipment.

In this paper, the authors present the equations of the hydrodynamic lubrication theory for conical slide bearings lubricated with the oil with properties described by the Rivlin-Ericksen model. It is assumed, that the considered lubricating oil shows non-Newtonian properties, i.e. it is an oil for which, apart from the classic dependence of oil viscosity on pressure, temperature and operating time, there is also a change in dynamic viscosity values caused by the changes of shear rate. The method of a small parameter was used to solve the conservation of momentum, stream continuity, and energy conservation equations. The small parameter method consists in presenting the sought functions (pressure, temperature, components of the velocity vector) in the form of a uniformly convergent series expansion in powers of a constant small parameter. These functions are substituted into the system of basic equations, and then the series are multiplied by the Cauchy method. By a comparison of the coefficients with the same powers of a small parameter, we obtain systems of partial differential equations, from which the subsequent approximations of unknowns of the sought functions are determined. The small parameter method separates the non-linear system of partial differential equations and creates several linear systems of equations. The aim of this work is to derive the equations describing and allowing the determination of the temperature distribution, hydrodynamic pressure distribution, velocity vector components, load carrying capacity, friction force and friction coefficient in the gap of conical slide bearing, lubricated with the oil of the properties described by the Rivlin-Ericksen model, taking into account its viscosity changes due to time of operation.

Future trends indicate that the demands on bevel and hypoid gears for higher power transmission and lower weight are continuously increasing. Beside typical fatigue failures such as pitting, tooth root breakage, and tooth flank fracture, spontaneous failures such as scuffing are often observed if the load-carrying capacity of the tribological system consisting of gears and lubricant is exceeded. This paper gives an overview of the newest findings on scuffing specifically on bevel and hypoid gears and discusses the hypoid-specific decisive influence parameters. Furthermore, the newly developed calculation method as well as its verification with test results and results from field application are presented.

Purpose The purpose of this paper is to determine parameters for an efficient running-in of gears and an improved method for the prediction of the tooth flank load carrying capacity. Design/methodology/approach In this contribution, a model for the calculation of the pitting life of involute spur gears is introduced, which is based on an extension of the life model according to Ioannides and Harris for rough surfaces. To achieve the most realistic thermal elastohydrodynamic lubrication simulation and stress calculation possible, measured real surfaces and elastic-plastic material properties of the area close to the surface are used. Special attention is paid to the compatibility of the fatigue life calculation for heterogeneous rough surfaces and their consistent consideration in the lifespan calculation. Findings A non-destructive running-in for twin-disc pairings can be performed using suitable operating parameters, which subsequently can be transferred to tooth flank tests. Using the extended life model according to Ioannides and Harris, an enhanced prediction of the tooth flank load carrying capacity is possible. Originality/value The developed extended life model includes a new numerical approach for calculating the tooth flank load carrying capacity. It has the potential to reliably support and hence to accelerate the design process of gears.

Demands for higher performance have caused a need for improved component characteristics, e.g. through surface strengthening of gears and increased cleanliness of gear steels. Unfortunately, a resultant drawback is that cracks in such high-strength gears are more often initiated in the material matrix at nonmetallic inclusions and not at the surface. In standardized calculation methods, the degree of cleanliness of steels is not yet directly correlated to the tooth root load-carrying capacity. This paper considers the effects of nonmetallic inclusions in the steel matrix on the tooth root strength based on the theoretical approach of Murakami.

Seismic performance of rectangular underground structures as a hot topic was studied systematically for decades. However, less attention was paid to the functionalities of the structural components. This paper presents a detailed numerical investigation of the seismic responses of rectangular underground structures and aims to explore the functionalities of the structural components. A three-dimensional numerical model for nonlinear dynamic responses simulations of underground structures was built, and the seismic responses of a rectangular underground structure under multiple ground motions were simulated. Dynamic response data, including internal forces, drifts of the columns and walls were obtained and analysed. Results of the proportions of seismic loads undertaken by the structural components explicitly illustrated the functionalities of the structural components before and during earthquakes. Then the failure process of Daikai station during the Great Hanshin earthquake was simulated, and the loading and deformation capacities of the slabs, as well as the intermediate columns and lateral walls, were presented. In terms of the load carrying capacities and functionalities of the structural components, the failure mechanism of the structures was better to understand, and the intermediate columns as the supporting components for the rectangular underground structures were proposed. The conclusions are beneficial to the seismic design of underground structures.

A constitutive model of SiC/SiC composites is developed which considers fiber failure and broken fibers’ load carrying capability. To obtain the in situ properties of SiC fibers, tensile tests are performed on the heat-treated fibers. A more universal fiber strength model is developed to describe the strength distribution of SiC fibers. In the constitutive model of SiC/SiC composites, the stress distribution of broken fibers is analyzed. To validate the in situ fiber strength distribution and the constitutive model, a tensile test is performed on SiC/SiC minicomposites. The predicted strength and stress-strain response of SiC/SiC minicomposites are in good agreement with the experimental results. The numerical calculations show that fiber failure nearly has no effect on the nonlinearity of SiC/SiC composites although the strength of composites will increase to infinity without fiber failure, and that the strength of the composites will decrease greatly if broken fibers do not carry the load.