In order to learn the variation laws of shear strength of side fillet weld post high temperatures, the tension tests were conducted after the double-strapped side fillet welded joints which were cooled down from diffe...In order to learn the variation laws of shear strength of side fillet weld post high temperatures, the tension tests were conducted after the double-strapped side fillet welded joints which were cooled down from different high temperatures with different cooling patterns. The tests indicate that specimens appear brittle fracture at the side fillet weld during the tension tests after cooling down. The fracture su（face is located in the welding throat. The maximum temperatures undergone and the cooling pattern are major factors influencing shear strength of side fillet welded joint post high temperatures. The shear strength reduces by 24% at most within 900 ~C. Based on the experimental results, the calculation formulas of shear strength of side fillet weld post high temperatures were proposed. Conclusions supply references for evaluation damage and reinforcement of steel structure post fire.展开更多
Since the previous strength prediction models for the perfobond rib connector were proposed based upon the results of push-out tests conducted on concretes with compressive strength below 50 MPa, push-out test is perf...Since the previous strength prediction models for the perfobond rib connector were proposed based upon the results of push-out tests conducted on concretes with compressive strength below 50 MPa, push-out test is performed on perfobond shear connectors applying ultra high performance concretes with compressive strength higher than 80 MPa to evaluate their shear resistance. The test variables are chosen to be the diameter and number of dowel holes and, the change in the shear strength of the perfobond rib connector is examined with respect to the strength of two types of UHPC: steel fiber-reinforced concrete with compressive strength of 180 MPa and concrete without steel fiber with compressive strength of 80 MPa. The test results reveal that higher concrete strength and larger number of holes increased the shear strength, and that higher increase rate in the shear strength was achieved by the dowel action. The comparison with the predictions obtained by the previous models shows that the experimental results are close to the values given by the model proposed by Oguejiofor and Hosain [1].展开更多
The seismic performance of steel reinforced ultra-high-strength concrete columns(SRSHC) with various shear-span ratios(λ) were studied through a series of experiments.The concrete compressive cube strength value of e...The seismic performance of steel reinforced ultra-high-strength concrete columns(SRSHC) with various shear-span ratios(λ) were studied through a series of experiments.The concrete compressive cube strength value of experimental specimens ranged from 92.9 MPa to 108.1 MPa.The main experimental variables affecting seismic performance of specimens were axial load ratio and stirrup reinforcement ratio.The columns(λ=2.75) subjected to low cyclic reversed lateral loads failed mainly in the flexural-shear mode failure and columns(λ≤2.0) subjected to low cyclic reversed lateral loads failed mainly in the shear mode failure.Shear force-displacement hysteretic curves and skeleton curves were drawn.Coefficient of the specimen displacement ductility was calculated.Experimental results indicate that ductility decreases with axial pressure ratio increasing,and increases with stirrup reinforcement ratio increasing.Limit values of axial pressure ratio and minimum stirrup reinforcement ratio of columns are proposed to satisfy definite ductility requirement.The suggested values provide a reference for engineering application and for the amendment of the current Chinese design code of steel reinforced concrete composite structures.展开更多
In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic...In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic shear sensitivity and ballistic performances of two high strength steels, 30CrMnSi and 35CrWMo, with similar static mechanical properties were investigated. Split Hopkin- son Pressure Bar （SHPB） for compression loading and ballistic experiments above the velocity of 1 000 m/s against thick concrete targets were performed. The SHPB and ballistic experimental results showed that the 30CrMnSi steel exhibits more adiabatic shear sensitivity, compared with the 35CrWMo steel. Even though these two steels have similar static mechanical properties, the 35CrWMo steel projectile exhibits better penetration performance than the 30CrMnSi projectile due to different adiabatic shear sensitivities.展开更多
With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, w...With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, which is determined by the inherent mechanical properties of high strength steel, makes molds prone to wear failure in the harsh service environments. In this paper, a finite element model is proposed for analyzing the value and distributions law of friction shear stress of contact surface of the pin disk. Through the simulation process of sliding wear, two kinds of different cladding materials of the pin specimens including H13 and Fe65, were experimented under three different loads by using the software ABAQUS. And then the pin-on- disk wear test at elevated temperature was conducted to verify the effectiveness of the simula-tion results. The results showed that the friction shear stress of pin with iron-based cladding and H13 steel was different under different loads, but the distribution was basically the same;the normal friction shear stress increased gradually along the direction of the pin movement, and the tangential shear stress increased gradually from the center of the pin to the outside of the circle;the value of the friction shear stress of the normal joints on the contact surface was periodically fluctuating in the whole dynamic analysis step, while it was basically stable in the tangential direction.展开更多
基金The research is supported by the China Postdoctoral Science Foundation （No. 2011M501428）.
文摘In order to learn the variation laws of shear strength of side fillet weld post high temperatures, the tension tests were conducted after the double-strapped side fillet welded joints which were cooled down from different high temperatures with different cooling patterns. The tests indicate that specimens appear brittle fracture at the side fillet weld during the tension tests after cooling down. The fracture su（face is located in the welding throat. The maximum temperatures undergone and the cooling pattern are major factors influencing shear strength of side fillet welded joint post high temperatures. The shear strength reduces by 24% at most within 900 ~C. Based on the experimental results, the calculation formulas of shear strength of side fillet weld post high temperatures were proposed. Conclusions supply references for evaluation damage and reinforcement of steel structure post fire.
文摘Since the previous strength prediction models for the perfobond rib connector were proposed based upon the results of push-out tests conducted on concretes with compressive strength below 50 MPa, push-out test is performed on perfobond shear connectors applying ultra high performance concretes with compressive strength higher than 80 MPa to evaluate their shear resistance. The test variables are chosen to be the diameter and number of dowel holes and, the change in the shear strength of the perfobond rib connector is examined with respect to the strength of two types of UHPC: steel fiber-reinforced concrete with compressive strength of 180 MPa and concrete without steel fiber with compressive strength of 80 MPa. The test results reveal that higher concrete strength and larger number of holes increased the shear strength, and that higher increase rate in the shear strength was achieved by the dowel action. The comparison with the predictions obtained by the previous models shows that the experimental results are close to the values given by the model proposed by Oguejiofor and Hosain [1].
基金Acknowledgement： The authors appreciate the support of the National Science Foundation of China （No. 50778025） and Hunan Provincial Natural Science Foundation of China （No. 07JJ6090）.
文摘The seismic performance of steel reinforced ultra-high-strength concrete columns(SRSHC) with various shear-span ratios(λ) were studied through a series of experiments.The concrete compressive cube strength value of experimental specimens ranged from 92.9 MPa to 108.1 MPa.The main experimental variables affecting seismic performance of specimens were axial load ratio and stirrup reinforcement ratio.The columns(λ=2.75) subjected to low cyclic reversed lateral loads failed mainly in the flexural-shear mode failure and columns(λ≤2.0) subjected to low cyclic reversed lateral loads failed mainly in the shear mode failure.Shear force-displacement hysteretic curves and skeleton curves were drawn.Coefficient of the specimen displacement ductility was calculated.Experimental results indicate that ductility decreases with axial pressure ratio increasing,and increases with stirrup reinforcement ratio increasing.Limit values of axial pressure ratio and minimum stirrup reinforcement ratio of columns are proposed to satisfy definite ductility requirement.The suggested values provide a reference for engineering application and for the amendment of the current Chinese design code of steel reinforced concrete composite structures.
文摘In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic shear sensitivity and ballistic performances of two high strength steels, 30CrMnSi and 35CrWMo, with similar static mechanical properties were investigated. Split Hopkin- son Pressure Bar （SHPB） for compression loading and ballistic experiments above the velocity of 1 000 m/s against thick concrete targets were performed. The SHPB and ballistic experimental results showed that the 30CrMnSi steel exhibits more adiabatic shear sensitivity, compared with the 35CrWMo steel. Even though these two steels have similar static mechanical properties, the 35CrWMo steel projectile exhibits better penetration performance than the 30CrMnSi projectile due to different adiabatic shear sensitivities.
文摘With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, which is determined by the inherent mechanical properties of high strength steel, makes molds prone to wear failure in the harsh service environments. In this paper, a finite element model is proposed for analyzing the value and distributions law of friction shear stress of contact surface of the pin disk. Through the simulation process of sliding wear, two kinds of different cladding materials of the pin specimens including H13 and Fe65, were experimented under three different loads by using the software ABAQUS. And then the pin-on- disk wear test at elevated temperature was conducted to verify the effectiveness of the simula-tion results. The results showed that the friction shear stress of pin with iron-based cladding and H13 steel was different under different loads, but the distribution was basically the same;the normal friction shear stress increased gradually along the direction of the pin movement, and the tangential shear stress increased gradually from the center of the pin to the outside of the circle;the value of the friction shear stress of the normal joints on the contact surface was periodically fluctuating in the whole dynamic analysis step, while it was basically stable in the tangential direction.
