New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can ...New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can carry out torsion strength test at high temperatures at the heating rate ranging from 10 ℃/min to 200 ℃/min.Torsion strength of high alumina brick,magnesia brick and Si3 N4 bonded SiC brick has been tested at different heating rates of 10 ℃/min,100 ℃/min and 200℃/min,separately. Results indicate that,for high alumina brick,the tested torsion strength at the heating rate of 10 ℃/min is very close to that at 100 ℃/min,but very different from that at 200 ℃/min. The tested torsion strength of magnesia brick at different heating rates differs greatly,while that of Si3 N4 bonded SiC brick is similar. This suggests that the structure of refractory materials with poor thermal shock resistance might be damaged when the heating rate of 200 ℃/min was applied,but the heating rate of 100 ℃/min is possible for a lot of refractory products. At fast heating rates,it takes only1 h to finish a test at elevated temperatures,thus saving a lot of time and energy.展开更多
This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ducti...This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ductile behavior of UHPC can also be attributed to the steel fiber reinforcement. This feature must be considered to provide rational explanation of the torsional behavior of UHPC structures. In this study, the proposed torsional design adopts a modified thin-walled tube theory so as to consider the tensile behavior of UHPC. And torsion test was conducted on thin-walled UHPC box beams to validate the proposed formula through comparison of the predicted torsional strength with the experimental results. The comparison of the predicted values of the cracking torque and torsional moment resistance with those observed in the torsional test of UHPC verified the validity of the design method. The contribution of the steel fibers to the torsional strength and cracking load was larger than that of the stirrups, but the stirrups appeared to contribute additionally to the torsional ductility. Accordingly, it is recommended that design should exploit effectively the contribution of the steel fiber rather than arrange a larger number of stirrups in UHPC structures subjected to torsion.展开更多
Based on the Finite Element Analysis and Thin Walled-Box girder Mechanics, two design concepts of adding box girders under main deck in order to increase the hull strength of ship are presented. By comparison and anal...Based on the Finite Element Analysis and Thin Walled-Box girder Mechanics, two design concepts of adding box girders under main deck in order to increase the hull strength of ship are presented. By comparison and analysis on the longitudinal strength, torsion strength and deck buckling between designed concepts and the original concept, it is found that by adding box girders under the main deck, the weight of hull structure is increased by lower than 10%, but the stress on the plate of the main deck is reduced by about 10%, the stress on the plating of the second deck is reduced about 20%. The shear stress on the plating of both of the main deck and second deck is reduced, but the shear stresses in several nodes are increased. Also the capability of resisting damage to ship is obviously increased by adding box girders under the main deck. The deck buckling is also increased by more than 90%. Consequently, the box girders added under the main deck are useful and effective to increase the strength of hull and ship survivability.展开更多
- The behavior of the reinforced concrete members subjected to combined torsion and shear is studied in this paper. Based on the skew bending failure pattern observed in tests, and according to the gradual increase in...- The behavior of the reinforced concrete members subjected to combined torsion and shear is studied in this paper. Based on the skew bending failure pattern observed in tests, and according to the gradual increase in strain on the concrete surface, a nonlinear full range analysis is performed for predicting the torque-twist relationship of members under combined torsion and shear for the ratio of torsion to shear is chosen bigger than 0.5 (T/ V b> 0.5). The test results are compared with the theoretical predictions.展开更多
文摘New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can carry out torsion strength test at high temperatures at the heating rate ranging from 10 ℃/min to 200 ℃/min.Torsion strength of high alumina brick,magnesia brick and Si3 N4 bonded SiC brick has been tested at different heating rates of 10 ℃/min,100 ℃/min and 200℃/min,separately. Results indicate that,for high alumina brick,the tested torsion strength at the heating rate of 10 ℃/min is very close to that at 100 ℃/min,but very different from that at 200 ℃/min. The tested torsion strength of magnesia brick at different heating rates differs greatly,while that of Si3 N4 bonded SiC brick is similar. This suggests that the structure of refractory materials with poor thermal shock resistance might be damaged when the heating rate of 200 ℃/min was applied,but the heating rate of 100 ℃/min is possible for a lot of refractory products. At fast heating rates,it takes only1 h to finish a test at elevated temperatures,thus saving a lot of time and energy.
文摘This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ductile behavior of UHPC can also be attributed to the steel fiber reinforcement. This feature must be considered to provide rational explanation of the torsional behavior of UHPC structures. In this study, the proposed torsional design adopts a modified thin-walled tube theory so as to consider the tensile behavior of UHPC. And torsion test was conducted on thin-walled UHPC box beams to validate the proposed formula through comparison of the predicted torsional strength with the experimental results. The comparison of the predicted values of the cracking torque and torsional moment resistance with those observed in the torsional test of UHPC verified the validity of the design method. The contribution of the steel fibers to the torsional strength and cracking load was larger than that of the stirrups, but the stirrups appeared to contribute additionally to the torsional ductility. Accordingly, it is recommended that design should exploit effectively the contribution of the steel fiber rather than arrange a larger number of stirrups in UHPC structures subjected to torsion.
文摘Based on the Finite Element Analysis and Thin Walled-Box girder Mechanics, two design concepts of adding box girders under main deck in order to increase the hull strength of ship are presented. By comparison and analysis on the longitudinal strength, torsion strength and deck buckling between designed concepts and the original concept, it is found that by adding box girders under the main deck, the weight of hull structure is increased by lower than 10%, but the stress on the plate of the main deck is reduced by about 10%, the stress on the plating of the second deck is reduced about 20%. The shear stress on the plating of both of the main deck and second deck is reduced, but the shear stresses in several nodes are increased. Also the capability of resisting damage to ship is obviously increased by adding box girders under the main deck. The deck buckling is also increased by more than 90%. Consequently, the box girders added under the main deck are useful and effective to increase the strength of hull and ship survivability.
文摘- The behavior of the reinforced concrete members subjected to combined torsion and shear is studied in this paper. Based on the skew bending failure pattern observed in tests, and according to the gradual increase in strain on the concrete surface, a nonlinear full range analysis is performed for predicting the torque-twist relationship of members under combined torsion and shear for the ratio of torsion to shear is chosen bigger than 0.5 (T/ V b> 0.5). The test results are compared with the theoretical predictions.
