Reinforced Concrete Beam's Stiffness Degeneration Regulation and its Calculation Formula Under the Action of Fatigue Load

Fatigue failure is a fatal damage for the reinforced concrete structure bearing fatigue load repeatedly. That how to estimate or describe the degree of fatigue damage is a challenge in areas of structure damage and lifespan estimation. Structure's stiffness degenerates irreversibly along with the damage progress. There is a certain inherent relevance between stiffness degeneration and fatigue damage. A series of fatigue tests were carried out to study stiffness degeneration regulation due to its simplicity and feasibility. According to the test results, reinforced concrete beam's stiffness degeneration presents a three-stage rules obviously, and the stiffness degeneration curves accord with "S" style. Based on the stiffness degeneration regulation, the reinforced concrete beams' stiffness degeneration calculation formula is obtained by fitting experimental data. The formula has a perfect goodness of contact area with 10 test beams' experimental results, and it can describes reinforced concrete beams' stiffness degeneration perfectly. The formula can be used to forecast the deformation developing. Meanwhile, the residual life of the structure can be used to decision structure's fatigue fracture and the degree of performance degradation.     

Study on Adsorption Characteristics of Coal to Gas in Geophysical Field

It is very important to mine safe exploitation, gas drawing and predict of coal and gas outburst that adsorption characteristics of coal to gas in geophysical field are studied. Adsorption and desorption characteristics of coal to gas in geophysical field have been reviewed in detail, then it is obtained that adsorption characteristics of coal to gas in electromagnetic field should be further studied . Adsorption and desorption characteristics of coal to methane in alternating electric field (AEF) have been studied mainly. Adsorption characteristics of three coal samples in AEF have been studied by means of Volume Method. The result shows that chemical properties and matter constituent of coal surface are no changed , adsorption and desorption of the coal samples in AEF well accord with Langmuir equation and two constants empirical formula, and because coal potential energy is increased and coal temperature is raised caused by Joule heat effect , adsorption ability of coal is decreased, and the desorption process is slowed down in AEF.