COMBINED bearings are made of spherical roller and thrust spherical roller bearings that are two important supports in different low-speed heavy-duty mechanisms, and the stability of their running state is the key to ensure supporting the normal operation of the mechanism. Based on the functionality of wellbore trajectory control tool, the LOADING distribution of the COMBINED bearing under pure radial and axial forces is theoretically studied. Two kinds of the limit state of the rolling elements movement called \Odd press" state and \Even press" state are considered, and the Hertzian line elastic contact model is used to deal with the contact between roller and raceway. The calculation results of the contact stress and radial displacement are very close to the analysis results, and the accuracy of the analysis results is verified by the radial displacement experiment. The results indicate that the radial load causes the radial displacement of the COMBINED bearing axis, which is about 5. 81*10-3 mm. The radial displacement can affect the guiding accuracy of the tool to a certain extent. The radial displacement can be reduced by adjusting the structural dimensions of the COMBINED bearing. The findings of this research can be employed to design COMBINED Spherical Roller Bearing (SRB) and Thrust Spherical Roller Bearing (TSRB) COMBINED bearings in actual engineering problems.

This article introduces three simple ideas that lead to the efficient design of regular moment frames. The finite module concept assumes that the moment frame may be construed as being composed of predesigned, imaginary rectangular modules that fit into the bays of the structure. Plastic design analysis aims at minimizing the demand-capacity ratios of elements of ductile moment frames by inducing the strength and stiffnesses of groups of members in accordance with certain design criteria, rather than investigating their suitability against the same rules of compliance. Collapse modes and stability conditions are imposed rather than investigated. In short, theory of structures is applied rather than followed. Plastic displacement control suggests that in addition to conducting failure analysis, the maximum displacements of plausible failure modes at incipient collapse should also be taken into consideration. While two collapse mechanisms may share the same carrying capacity, their maximum displacements may be different.

The study investigated the effect of COMBINED LOADING on end-plate moment connection considering the interaction of bending moments, axial forces and twisting moments. In some cases, beam-to-column joints can be subjected to the simultaneous action of bending moments, axial forces and twisting moments. Current specifications for steel joints do not take into account the presence of axial forces (tension and / or compression) or twisting moments in the joints. Although the axial force or twisting moments that transferred from the beam is usually low, it may, in some situations attain values which can lead to a considerable effect on the connections behaviour and significantly reduce the joint flexural capacity. Unfortunately, few studies considering the bending moment versus axial force interactions have been reported and there aren’ t any reports considering bending moments versus twisting moments interactions or combination of all the mentioned cases of loads. The lack of knowledge for understanding the performance of end-plate moment connection under COMBINED loads may lead to unreasonable or even unsafe design, so in this study a combination of different loads have been examined. Therefore two extended End-Plate connections with different behaviour modeled using finite element method of analysis. The interactions between connection components (bolts, members and endplate) were accurately modelled to simulate the actual behaviour of connections. Both material and geometric nonlinearities were considered. At first the behavior of these models are investigated in pure bending application and numerical results validated against experimental data. The suggested finite element models showed good agreement with experimental results. The level of axial forces in joints of structures can be significant and has a significant influence on characteristics of joints. Because of the existence of this force in the moment resisting frames, the combination of bending and axial force in beams should be considered. Structures under fire situations where the effects of beam thermal expansion and membrane action can induce significant axial forces in the connection is a common condition. The results show that even in small amount of axial force the mode of failure and moment capacity of connection can change. Axial tensile forces decrease the initial stiffness of connection and axial compressive forces increase the stiffness. In many applications beams are eccentrically loaded and as a result experience twisting loads in combination with bending. The interaction effects due to torsion acting in combination with bending can reduce the capacity of the beam and initial stiffness of connection. Finally axial forces were added to the previous models so they experienced a combination of axial force, bending and twisting moment. The results indicated that the level and direction of axial force significantly modified the connection response. It was observed that compression forces significantly decrease the bending capacity of the models and lateral-torsional buckling of beam occures in all models. Tension forces can reduce the effect of torsion and in many cases they caused the bolts ruptured. Moreover, interaction diagram for predicting the bending capacity considering interaction of bending, torsion and axial forces are proposed based on the results from finite element analysis.

Hypotension associated with spinal anesthesia for cesarean section is still a clinical problem. The role of crystalloid preLOADING to prevent hypotension associated with spinal anesthesia in parturients during cesarean section has been challenged. However, studies with crystalloids predict that fluid LOADING should be more efficacious if administered immediately after induction of spinal anesthesia. The effects of colloid LOADING after spinal anesthesia in cesarean section have not been studied enough. The aim of this study was to compare pre and co-LOADING of hetastarch for the prevention of hypotension following spinal anesthesia for cesarean delivery.Materials and Methods: This randomized clinical trial study was performed in 112 parturients (ASA I or II) undergoing elective cesarean section. Patients were randomly allocated to one of the two groups to receive rapid infusion of 500 ml of 6% hydroxyethylstarch (HES) before spinal anesthesia (preLOADING group, n=56), or rapid infusion of 500 ml of HES after induction of spinal anesthesia (co-LOADING group, n=56). The incidence of hypotension and the amount of vasopressor, (ephedrine 5 mg/mL+phenylephrine 25 micg/mL) were compared in the treatment of hypotension.Results: There was no significant difference in hypotension between the two groups (P=0.58). The preLOADING group used 2.2±1 ml of vasopressor mixture compared with 1.7±0.7 ml in the co-LOADING group (P=0.04) and the difference was significant.Conclusion: Colloid LOADING after induction of spinal anesthesia is as effective as preLOADING in reducing hypotension in cesarean section.

Theoretical predictions regarding the ultimate resistance of slender plate girders to applied shear LOADING, based on existing theories and formulas, show close correlation with the test data presented. When a plate girder is subjected to a bending moment in addition to shear, the determination of the ultimate resistance becomes more complex. Herein, an interaction formula for the ultimate resistance of slender plate girders to COMBINED bending and shear LOADING isproposed, which shows satisfactory correlation with the available theories and which is acceptable for practical purposes. The proposed interaction equation covers web panel aspect ratios, bw/dw, from 1 to 2 and slender ratios, dw/tw, from 150 to 300.

Due to the correlation of natural vibration modes of skewed bridges, and the multi-directional nature of the earthquake ground motions; piers of skewed bridges would be subjected to COMBINED axial, flexural and torsional LOADINGs. The characteristic of COMBINED LOADING of the piers depends upon several parameters including the strong ground motion characteristics and the structural system type. In this research, seismic performance of a group of torsion sensitive skewed bridges with three different pier-deck connections is studied. Skew angles vary from 0° to 60°. Seismic performance of the bridges is investigated conducting bidirectional nonlinear time history analysis in OpenSees. Considering the effect of different pier-deck connection types, COMBINED LOADING demand on the skewed piers is compared with those on the straight piers. On the basis of results, for both pinned and fixed piers, ductility demand increases with the skew angle. Opposed to pinned piers, fixed piers are subjected to COMBINED torsional-flexural LOADINGs, and the torsional demand increases with an increase in the skew angle. The value of torsional demand on fixed piers is limited to one half of cracking torque of the section (Tcr/2). Concerning the collapse prevention criteria, 30 degree skew angle is found to be a threshold skew angle. For bridges with skew angles greater than 30 degree, applying monolithic pier-deck connections is more sensible.

Recently, strengthening of steel sections using carbon fiber reinforced polymer (CFRP) has come to the attention of many researchers. For various reasons, such structures may be placed under COMBINED loads. The deficiency in steel members may be due to errors caused by construction, fatigue cracking, and other reasons. This study investigated the behavior of deficient square hollow section (SHS) steel members strengthened by CFRP sheets under two types of the COMBINED loads. To study the effect of CFRP strengthening on the structural behavior of the deficient steel members, 17 specimens, 12 of which were strengthened using CFRP sheets, were analyzed. To analyze the steel members, three dimensional (3D) modeling and nonlinear static analysis methods were applied, using ANSYS software. The results showed that CFRP strengthening had an impact on raising the ultimate capacity of deficient steel members and could recover the strength lost due to deficiency, and the impact of CFRP strengthening on rising and recovering the ultimate capacity of the steel members under LOADING scenario 2 was more than the steel members under scenario 1.

Fast fracture is one of the major failure modes in brittle polymers. Generally, crack growth in these polymers may occur under COMBINED tensile-shear LOADING. However, the fracture test data reported previously for some dental restorative resins can not be predicted by using the available fracture criteria. In this paper, a modified fracture criterion is used for estimating the fracture load for the mentioned resin samples. It is shown that by considering a more accurate description for the crack tip stresses and also by accounting for the craze zone effects in front of the crack tip, the modified criterion presents significantly better predictions for the fracture resistance in such brittle polymers.

Generally, in-served cylindrical shells buckling usually takes place not merely under one of the basic loads, i. e., axial compression, lateral pressure, and torsion, but under a combination of them. The buckling behavior of fiber-metal laminate (FML) cylindrical shells under COMBINED axial and torsional LOADING is studied in this paper. The Kirchhoff Love-type assumption is employed to study the axial buckling load. Then, an extended finite element (FE) model is presented and results are compared. A number of consequential parameters such as lay-up arrangement, metal type and metal volume fraction are employed and enhancement of buckling behavior of the shell is also studied. Finally, the interaction of axial /torsional LOADING is analyzed and discussed. The results show that as the metal volume fraction rises to 15%, the endurable buckling load increases almost 43% more than the state in which there is no metal layer. The numerical results show that increasing the metal volume percentage leads to a decrease in buckling performance of the structure under axial LOADING.