| The characteristics of the concrete structure composed of reinforcement and concrete is a good performance,low cost,wide range of application.A large number of reinforced concrete structures not reach the predetermined year and the desired effect due to various reasons,that is the problem of inadequate structural design,is the problem of the use of adverse load,is the main problem of the durability of structure,particularly the concrete bridges under natural conditions in coastal,offshore,lakes and factories areas.Thanks to the influences of various corrosive factors in the environment,resulting in concrete shedding,steel corrosion and so on,so that the loss of the durability,then not reach the useful year,which has become an important proliem in the projects.The study T-shape concrete beams of flexural performance is completed under acid rain environment(sulfuric acid conditions and nitrate acid condition),salt freezing condition,frozen condition and salt corrosion condition.The study are as follows:To study the variation on the mechanical properties of T-shaped concrete beams under acid rain.4 beams soaking 20,40,60,80 days in the pH=5 sulphuric acid solution and then experimental study on T-shaped concrete beams by three points loading to simulating effects on acid rain condition.The variation of the crack,cracking load,ultimate load,stiffness,and reinforcement strain were researched under different sulfuric acid time.The result show that T-shaped concrete beams remain bending damage of under-reinforced beam after corroding;the longer nitrate time,the lower cracking load and ultimate load,but reaching a certain level the ultimate load having no obvious influence;The cross-displacement curve slow growth and being roughly linear relationship in elastic stage,the longer sulfuric acid time,the smaller power making test beam displacement mutation and the bending stiffness in yield phase.Analyze the carrying capacity of T-shaped concrete beams by using the least square method,its attenuation formula and decay curve are broadly in line with the changing rule of the exponential function.To study the variation on the mechanical properties of T-shaped concrete beams under acid rain.4 beams soaking 20,40,60,80 days in the pH=4.5 under nitrate solution and then experimental study on T-shaped concrete beams by three points loading to simulating effects on acid rain condition.The variation of the crack,cracking load,ultimate load,stiffness,and reinforcement strain were researched under different under nitrate time.The result show that T-shaped concrete beams remain bending damage of under-reinforced beam after corroding;the longer nitrate time,the lower cracking load and ultimate load,but reaching a certain level the ultimate load having no obvious influence;The cross-displacement curve slow growth and being roughly linear relationship in elastic stage,the longer sulfuric acid time,the smaller power making test beam displacement mutation and the bending stiffness in yield phase.Analyze the carrying capacity of T-shaped concrete beams by using the least square method,its attenuation formula and decay curve are broadly in line with the changing rule of the exponential function.To study the variation on the mechanical properties of T-shaped concrete beams under salt erosion condition.4 beams soaking 20、40、60、80 days in 3%Nacl solution and then experimental study on T-shaped concrete beams by three points loading to simulating effects in the coastal and lake areas.The variation of the crack,cracking load,ultimate load,stiffness,and reinforcement strain were researched under different under salt erosion time.The result show that the product of erosion early dense concrete internal structure.With the developing of corrosion,the mechanical properties of concrete and steel decreased,thus the cracking load,the ultimate load and the stiffness of the test beams have experienced a course that a slight increase and then drop.Analyze the carrying capacity of T-shaped concrete beams by using the least square method,its attenuation formula and decay curve are broadly in line with the changing rule of the exponential function.To study the variation on the mechanical properties of T-shaped concrete beams under salt erosion condition.4 beams soaking in 3%Nacl solution and placing 20、40、60、80 days at minus 15 degrees Celsius outside then experimental study on T-shaped concrete beams by three points loading to simulating effects in cold winter of northern areas.The variation of the crack,cracking load,ultimate load,stiffness,and reinforcement strain were researched under different salt freezing time.The result show that T-shaped concrete beams remain bending damage of under-reinforced beam after freezing;the longer salt freezing time,the lower cracking load,ultimate load and stiffness,the worse concrete surface shedding situation.The salt freezing has slight effect on the strain of reinforcement in specimens,while the strain reduces significantly with the long salt freeze cycles.Analyze the carrying capacity of T-shaped concrete beams by using the least square method,its attenuation formula and decay curve are broadly in line with the changing rule of the exponential function.To study the variation on the mechanical properties of T-shaped concrete beams under arctic conditions.4 beams placing 20、40、60、80 days at minus 20 degrees Celsius outside and watering process then experimental study on T-shaped concrete beams by three points loading to simulating effects in arctic winter of northern areas.The variation of the crack,cracking load,ultimate load,stiffness,and reinforcement strain were researched under different freezing time.The result show that the resistance to cracking of T-shaped concrete beams reduce significantly and the cracking load drop;the mechanical properties of steel have little effect but the properties of concrete change significantly;the displacement of test beams change in apparent after reinforcement yielding;the longer erosion time,the worse maximum displacement and the lower reinforced strain.Analyze the carrying capacity of T-shaped concrete beams by using the least square method,its attenuation formula and decay curve are broadly in line with the changing rule of the exponential function. |
