Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of t...Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.展开更多
The former gas pipeline operating pressure transmission determined mostly according to the determined formula into the corresponding pipeline parameters are obtained, and the parameters of the actual pipeline due to m...The former gas pipeline operating pressure transmission determined mostly according to the determined formula into the corresponding pipeline parameters are obtained, and the parameters of the actual pipeline due to many reasons, such as measurement error, production batch, etc., is not a fixed value. This paper on pipeline integrity established limit state equation, using Monte Carlo method to calculate the gas pipeline in different pressures of reliability, according to the API （American Petroleum Institute） 579 recommended target reliability to determine the operating pressure of the different regions, and design coefficient method, the calculated results are compared, results of calculation reliability is more reasonable and improve the delivery pressure of the area, the pipeline safety management provides the basis.展开更多
文摘Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.
文摘The former gas pipeline operating pressure transmission determined mostly according to the determined formula into the corresponding pipeline parameters are obtained, and the parameters of the actual pipeline due to many reasons, such as measurement error, production batch, etc., is not a fixed value. This paper on pipeline integrity established limit state equation, using Monte Carlo method to calculate the gas pipeline in different pressures of reliability, according to the API （American Petroleum Institute） 579 recommended target reliability to determine the operating pressure of the different regions, and design coefficient method, the calculated results are compared, results of calculation reliability is more reasonable and improve the delivery pressure of the area, the pipeline safety management provides the basis.
