A Study On Shear-Flexural Behavior Of Reinforced Concrete Beams With An Opening

For the complexity of modern architecture in a variety of building auxiliary facilities,pipelines are laid everywhere.That pipelines are through from under the beam is the traditional method which not only occupys the building space,but also increase the project cost.So more and more engineerings apply the beam with an opening that through a variety of pipelines from the beam holes,to avoid the building space and reduce the project cost obviously.But holes damage the integrity and continuity of the beam,and weaken the bearing capacity,stiffness and other mechanical properties of the beam,so to ensure safe and reliable structure,the performance of open-hole concrete beam force systemly has an important social and economic benefits.Abroad,study in the open-hole concrete Beams in this area started earlier,the domestic research relatively late,but also carried out a large number of test studies,and made many achievements,but the use of finite element software off the hole beam force performance and changelaw aspects of the study was not thorough enough.In this paper,the finite element software to model test study to open a hole concrete simply supported beam under concentrated load,the pore size and pore location outside of the hole Concrete Beams law.When the porosity of not greater than 0.2,the bearing capacity of beams are less affected,reducing the range of 5 to 10%;when the porosity of between 0.2 to 0.4,its carrying capacity is reduced in the range of 15 to 30 percent;when the porosity of 0.4 to 0.5,its carrying capacity decreased 30%to 40%.Suggesting practical engineering,the pore size is generally not more than 0.4h.Appropriate reinforcement component normal to open holes in the large shear region,the ultimate bearing capacity of the beam fell more holes of pure bending segment is relatively small;holes center closer the ultimate bearing capacity of bearing beam decreased in 40%to 50%;holes in the bearing and the load point of connection location,its carrying capacity decreased more significantly,the reduction ranges up to 50%～60%or more.Project to avoid the holes too close from the bearing,should avoid the holes in the bearing and the load point of connection.Open holes in the tension zone,the ultimate bearing capacity of the beam fell in the range of 5 to 10%;open holes in the compression zone decreased significantly increases,the decrease is generally 15 to 40 percent.The proposed works in the holes should be as close as possible to the tension zone,in order to increase the area of the concrete compression zone.On this basis,the appropriate position and size of the opening hole of the frame structure of an office building to ensure that the office in the case of carrying capacity is not affected pipeline through the beam holes,effectively reducing-storey.The economic benefits are obvious,the research reference for similar projects.