Following the collapse of the World Trade Center towers, investigating the building resistance and providing the safety of residents in case of fire have attracted the attention of engineers more than ever. In this regard, similar to buildings, gas and liquid containment structures, vehicles, planes, and vessel fuselages are examples of engineering usage which need to be designed against fire. It was shown that inelastic or elastic buckling of steel plate webs, that experience plastic buckling at normal temperatures, is a possible phenomenon at elevated temperatures owing to the deterioration of mechanical properties, i. e., a change in the failure mode, is to be expected. Therefore, regarding the importance of the issue and its application in the industry, it is necessary to investigate the behavior of the I-shaped plate girders against fire. In this research, SHEAR behaviors of long steel plate girder web panels subjected to pure SHEAR loading are investigated at elevated temperatures by the nonlinear finite element method. Therefore, web panel SHEAR design relationships mentioned in AISC360-16 specification is modified to be used in fire conditions. This is achieved by direct utilization of steel stress-strain reduction factors in EN1993-1-2 at elevated temperatures. It is observed that the adopted equation of AISC360-16 for fire situations yields values that are more non-conservative such that the difference reaches almost 18%. On the other hand, AISC equations are more accurate and in the safe region for compact plates. However, these equations lead to the unsafe condition at higher slenderness values. In this regard, nonlinear finite element analysis results were employed to modify the AISC 360-16 equation for predicting the ULTIMATE SHEAR STRENGTH of long steel plate girder web panels by considering the STRENGTH degradation caused by high slenderness, high temperature, and initial geometrical imperfections. Comparison of the results corroborated the appropriate accuracy of the proposed equations.

The contribution of diagonal stiffeners in the SHEAR capacity of composite plate girders has not been studied so far. In this study, the behavior of diagonally stiffened simply supported composite plate girders is investigated and a theoretical formula is proposed to estimate the ULTIMATE SHEAR STRENGTH of such girders. The proposed analytical method considers the tension field action within the plate girder web panel and the SHEAR failure of the concrete slab. Several validated finite element models of the composite plate girders, having different configurations of diagonal stiffeners, are also generated to verify the proposed method by comparing the analytical and numerical outcomes. These three-dimensional finite element models are developed to account for the geometric and material nonlinear behavior of composite girders. The models are first verified by experimental values obtained for girders with no diagonal stiffeners tested by other researchers and afterwards different configurations of diagonal stiffeners are added to the models. A total of four tested specimens are selected from previous studies. Based on the results of finite element analyses, a design method is proposed which incorporates the effects of the concrete slab, the composite action, and the web SHEAR buckling of composite girders. The proposed method is approximate, simple and does not require any complex mathematical operations and can be applied to composite plate girders at the preliminary stages of design. The calculated ULTIMATE SHEAR STRENGTHs using the proposed method are in good agreement with both numerical results and experimental values, which indicates that the proposed analytical equations can be applied to predict the ULTIMATE SHEAR STRENGTH of girders for design office use. In comparison with un-stiffened girders, it is also observed that diagonal stiffeners are able to reduce the buckling effects of the web steel plate, increase elastic SHEAR buckling STRENGTH and therefore the ULTIMATE SHEAR capacity of the girders.

Statement of Problem: Evaluation of new adhesives efficacy in bonding orthodontic brackets to enamel has led to different results. The new measuring method, micro-SHEAR bond STRENGTH, is preferred as an accurate method due to its ability to reduce confounding factors.Purpose: The purpose of this study was to evaluate and compare the micro-SHEAR bond STRENGTH of three different adhesive systems for enamel surface preparation before bracket bonding.Materials and Method: In this experimental study, 90 extracted premolars were randomly divided into three groups of 30. Transbond XT was bonded to enamel after enamel surface preparation with acid etch in the first (control) group, Transbond plus self-etch primer in second group, and Adper prompt L-pop self-etch adhesive in third group. Then each group was randomly divided into two subgroups of 15. Micro-SHEAR bond test was performed after 24 hours (T1) and 3-months (T2). Bond failure mode was also evaluated according to Adhesive Remnant Index (ARI). Two way ANOVA and Tukey tests were used for bond STRENGTH evaluation in groups, and mode of bond failure was analyzed with Kruskall Wallis and Mann Whitney tests.Results: The highest bond STRENGTH was found in acid etch group (29.17 MPa). Difference of bond STRENGTH at two intervals was statistically significant in all groups ( p <0.001). Bond STRENGTH difference between T1 and T2 was also significant in three groups ( p <0.001). However changes over time in three groups did not reveal any significant differences ( p = 0.091). Bond failure analysis demonstrated significant differences in ARI between groups.Conclusion: Bond STRENGTH of acid etch group was the highest and self etch primer showed higher bond STRENGTH than self etch adhesive group. Less adhesive remnant was found in self etch group.

In this paper a new method based on Strut-and-Tie Model (STM) is proposed to determine the SHEAR capacity of simply supported RC deep beams and an efficiency factor for concrete with considering the effect of web reinforcements. It is assumed that, the total carried SHEAR force by RC deep beam provided by two independent resistance, namely diagonal concrete strut due to strut-and-tie mechanism and the equivalent resisting force resulted by web reinforcements, web reinforcing reduces the concrete compression softening effect with preventing from the diagonal cracks opening or concrete splitting. The unknown function and parameters are determined from 324 experimental results obtained by other researchers. To validate the proposed method, the obtained results are compared with some of the existing methods and codes such as ACI 318-05 and CSA. The results indicate that the proposed method is capable to predict the SHEAR STRENGTH of variety of deep beams with acceptable accuracy.

In this paper failure mechanism of a joint which was welded by friction stir spot welding method was studied. The 5052 aluminum joint was loaded under tensile-SHEAR condition. To find out failure mechanism, several tests were conducted such as: strain-stress, macrography, and Vickers hardness. Results of strain-stress test state the stages of failure and crack initiation and propagation. Macrography analysis was done in several stages with different penetration depths. It was shown that the material flow, the critical surface of the coupon, and the determined zones were more possible to generate crack. Finally, by using Vickers hardness test, the susceptible zones to crack generation and propagation can be specified.

Background & Aim: More than 30 years has passed since introduction of glass-ionomer cement as a dental restorative material, luting cement and liner. Although they are sensitive to moisture and desiccation during the initial setting stages, relative poor physical properties because of chemical bonding to tooth substrate, and long-term esthetic quality, they are recommended for restoring anterior and posterior primary teeth, cervical lesions and root caries of permanent teeth. In this study, SHEAR bond STRENGTH of Fuji II was compared with of ariadent glass-ionomer cements. Materials & Methods: Thirty intact extracted primary molars were prepared for this study. Selected teeth were divided in two groups of 5. Sample were free of caries, fracture, crack, discoloration or any structural abnormality. The dentin of buccal surface of teeth were exposed by microtome apparatus. The surface was conditioned by polyacrylic acid (10%) for 20 seconds. Glass ionomer cements (Fuji II, and Ariadent) were prepared in a plastic cylinders (15 of each) and attached to the dentin of teeth horizontally. SHEAR bond stength of materials was measured by instron (Model 1159).Results: Mean SHEAR bond STRENGTH of Ariadent cement was 4.2±1.9 Mpa while 7.4±1.5 Mpa was of Fuji II cement (P=0.000).Failure mode was similar between two cements (P=ns). The most prevalent type of failure mode was cohesive failure leaving a firmly attached thin and homogenous layer of cement to dentin, in both groups.Conclusion: It appears that SHEAR bond strenght of Ariadent cement to primary tooth is much lower than of Fuji II.

The main objective of this study is to propose the Strut-and-Tie method (STM) to predict the SHEAR capacity of simply supported RC deep beams SHEAR-STRENGTHened with carbon fiber reinforced polymers (CFRP). It is assumed that, the total carried SHEAR force by SHEAR-STRENGTHened RC deep beam provided by three independent resistance, namely diagonal concrete strut due to Strut-and-tie mechanism, and the equivalent resisting force resulted by with web reinforcement and FRP layer. The STM approach is regressioned with 104 specimens SHEAR-STRENGTHened with different scheme which are modelled and analyzed through the Non Linear finite elements method and analyzed according under Push over load. For verifying of the accuracy of proposed method, it was used to determine the SHEAR capacity of specimens which have been tested by other researchers. Obtained results were compared with experimental data, that this comparison indicate the proposed method is capable to predict the SHEAR STRENGTH of STRENGTHened deep beams with externally bonded (EB) CFRP with acceptable accuracy.