Papers by Author: Kao Zhong Zhao

Abstract: The concrete composite box steel girder floor system is a new box-section ribbed hollow floor system. It is an integral structure integrated the girder and plates by the “composite box”, one of the precast composite members and the rear casting ribbed girder and has been widely used in the buildings with large span and heavy load. The article researches its whole process under the effects of the fire and the service load. In the whole process of test, the temperature field, vertical displacement, displacement within the plane, plate edge corner and other parameters of the different sections have been measured. The results show that: the concrete at the bottom plate of the composite box bottom plate quickly bursts off during the fire; later, the bottom plate of the composite box is out of operation; the floor structure becomes cross girder structure; as the temperature rises, after the floor system structure becomes the cross girder structure, the torque of the four-side ribbed girder of the floor system increases and the diagonal cracks occur on the four-side ribbed girder; as the temperature rises, there is large temperature gradient on the floor system ribbed girder along with the cross section height; the flexural deformation occurs to the floor system while the expanding deflection occurs in the plane; the maximum vertical displacement is achieved after the temperature rise stops; along with the drop of the temperature, the flexural deformation gradually recovers; after the tested temperature rise has been conducted for 292 minutes, the floor system still has good fire resistant capacity

Abstract: channel - masonry - concrete composite structures underpinning is a new type of underpinning technology, the two channel steel and the concrete of compression flange and the masonry between the channel combined into an overall flexural members, it can used in masonry structure underpinning the transformation of the wall, it has simple construction, safety and reliability, the combination of large carrying capacity and other characteristics. Through this combination of three members in bending tests, we can get, reinforced by setting off key, channel, masonry and concrete can form a combination of flexural members to work together, channels tensile stress, concrete bear stress, masonry between the channel improved stability of the web and shear capacity of the beam, we gives the flexural capacity calculation method of the composite structure through analysis.

Abstract: Concrete composite beam floor cage floor as a new form , with a saving of steel and concrete , lighter weight, the advantages of high capacity , and has been more widely used in engineering. Therefore , to carry out the new concrete composite beam floor cages fire behavior for large spaces , large span areas is necessary. This article is the use of finite element software ANSYS multi-span composite floor beams cages fire tests to simulate life and death through SOLID70 unit features analog composite bottom plate before and after bursting floor temperature field and gives composite floor box overall temperature distribution along the rib cloud cover and the temperature of the beam cross-section of different heights - time curve , finally, the simulation results and experimental conditions were compared and analyzed , the main draw the following conclusions : the use of ANSYS thermal unit SOLID70 cell function and death can be simulated temperature distribution in case of fire concrete composite floor beam floor cages before and after bursting through the ribbed section of different heights temperature - time curve can be seen, the test results agree well with the simulation results ; testing process with increasing temperature , floor surface inlets, stacked boxes floor temperature contours directly reflects the law during the test floor surface appears inlets .

Abstract: In recent years, natural disasters occurred more frequently in our country, dangerous housing in rural areas often cause a lot of casualties and property losses. Due to the shortage of national financial, the government decided to focus financial support on the renovation of dilapidated buildings. In order to have a deep understand of the rural structure, distribution law and the proportion of the dilapidated housing, after the survey of the housing situation in Dongying County Dongying City, Jiaxiang County Jining City and Yiyuan County Zibo City, this article made the statistics and analysis of the status of housing in these three counties. The result of analysis and statistics show that the rural housing mainly conclude adobe housing, brick masonry housing and block masonry housing, the proportion of dilapidated houses in rural housing is about 10.9%, the dilapidated buildings are mainly distributed in the mountain, because the mountain areas foundation of economic is weak, and the housing structure is mainly in the form of adobe housing and stone masonry housing. The main types of dilapidated housing are adobe housing and stone masonry housing primarily, the brick masonry housing newly built is in relatively low risk level. The government finances should inclined to transform the dilapidated housing in the mountain area first. In order to improve the quality of new housing in rural areas, this new housing in rural areas will also need to pay attention to the problem made some conclusions.

Abstract: Assembly box concrete hollow floor sructure is a new-style whole structure that are constituted by the a cross section of a concrete box composed of small prefabricated components (concrete superposition box) and a cast-in-place concrete rib beam.The internal force distribution law was analyzed in this paper, based on the static load experiment with a multi span column-supported assembly box concrete hollow floor.The findings prove that the prefabricated boxs and cast-in-situ concrete ribbed beams are able to form a whole to jointly bear external forces, that the internal force distribution law is basically the same with the solid cast-in-situ concrete floor with no beams, and that the floor structure can be simplified to the column strip and middle strip.The specific distribution ratios between the minus moment and the plus moment of the column strip and middle strip respectively are as follows. For the angel area floor(contianed edge beams), the ratio of midspan section is 0.537:0.463, the ratio of support section is 0.816:0.184; for the edge area floor(contianed edge beams), the ratio of midspan section is 0.51:0.49, the ratio of support section is 0.808：0.192; for the inner area floor, the ratio of midspan section is 0.55:0.45, the ratio of support section is 0.75:0.25.

Abstract: In masonry structure transformation, due to the removal of walls, force transmission path and force structure mechanism of load-bearing walls will be changed. So it become greatly important to adopt a safe, applicable, economic and reasonable underpinning method. This paper introduces several underpinning methods of masonry structure modification, which summarizes the advantages and disadvantages of them. Their characteristics and using condition are discusses in the paper. Some conclusions which are drawn may be referenced for the future engineering practice.

Abstract: The concrete-filled glass fiber reinforced gypsum wall panel is a kind of panel that the inside cavums of the glass fiber hollow gypsum panel is filled with concrete. The experimental results indicate that the concrete-filled glass fiber reinforced gypsum wall panel which has a better performance of the force and can be used to be the bearing wall of a building can form a novel structural system. When the beams supporting the wall panels, the wall panels which under the beams is in local state of compression. It were gained that when the wall panels are in the local compression state , local pressure loads are primarily borne by the concrete core columns and fiber gypsum board will damage in advance through the eighteen experimental wall panel specimens which in local compression. The test results show that the final destruction of the concrete is caused by being crushed and the contribution of the gypsum wall panel to local compression bearing is small. Compressive stress can only spread in the local loading on concrete core columns, cannot be expanded into an adjacent stud. Finally, the local compression bearing capacity calculation formula of the concrete-filled glass fiber reinforced gypsum wall panel is obtained by analysis of the test results.

Abstract: A serial of fire tests have been conducted to study the fire resistance of the post-installed rebar connection with organic adhesive. Research variables include three kinds of anchorage depth. Loads are applied to specimens through lever and remain a constant throughout the whole process of the tests. The temperatures of connections are elevated following the ISO834 curve and the failure is controlled by excessive deflection of bonded-in rebar beams. The test results show that anchorage depth has a great influence on the performance of bonded-in rebar beams exposed to fire. Beams using organic adhesive fail suddenly with obvious rebar slip, and behave with poor fire endurance.

Abstract: The concrete-filled glass fiber reinforced gypsum wall panel is a kind of panel that the inside cavums of the glass fiber hollow gypsum panel are filled with concrete, which can be used as the bearing wall of a building. The influences of eccentricity distance and height to thickness ratio on the bearing capacity of the compression wall panels were studied, and the failure mechanism and bearing capacity of compression wall panels were gained through the experiments of twenty-seven(nine groups) axial compression wall panel specimens and twenty-seven(nine groups) eccentric compression wall panel specimens. The analysis results indicate that the bearing capacity of compression wall panels is obviously affected by the eccentricity distance and height to thickness ratio, and there is a linear relation between bearing capacity and eccentricity distance. The bearing capacity calculation formula of the concrete-filled glass fiber reinforced gypsum wall panel is obtained by regression analysis, which provides reliable gist for structural design of concrete-filled glass fiber reinforced gypsum wall panel buildings.