Xiao Xiong Zha

Experimental Research on Mechanical Behavior of GFRP Bars under High Temperature

Experimental results on tensile mechanics properties of GFRP bars at high temperatures are present in this paper. Thirty commercially produced GFRP tensile specimens of 8mm diameter were tested at high temperature ranging from 10°Cup to 500°C. Tensile test result indicates that, the ultimate tensile stress has significant reduction at two temperature zones, one is glass transition temperature of epoxy resin (80-120°C), with strength degradation 22%, the second is the soften temperature of glass fibers(about 400°C), the strength decrease drastically with almost linear rate and remained 33% residual strength at 500°C. The elastic modulus remained unchanged until glass transition temperature of epoxy resin, and the modulus declined linearly with the temperature elevating. Stress-strain relationships of GFRP bars exhibit liner performance even at high temperatures.

Study on the Optimal Design of the Members of Contaniner Building with Building Materials I: Side Board Optimization

Container, as a light steel structure, being increasingly used in building construction, containers used in construction has many advantages and applications. However, the current study mostly from the view of the architecture, as for the mechanical properties of the container building has not mentioned, that brings obstacles of the application and development of the container building. Based on the software package of HyperWorks and optimization design theory, the cross-sectional size of container building is taken as design variables, and then selected objective function and constraint functions. Finally, calculated by software, get the optimal cross-sectional dimension.

Study on the Optimal Design of the Members of Contaniner Building with Building Materials II: Joint and Corner Column Optimization

Containers are widely used for building, in order to promote the use of container building, it is necessary to do the research on optimal design. The corresponding optimal design has been achieved through the software package of HyperWorks, the lightest total weight is taken as the objective function, and the strength and stiffness are taken as the constraint conditions. Based on the finite element analysis of the joint and corner column, the cross-sectional size is taken as design variables, and then the optimization design of joint and corner column of container building is made.

Smoke Control in Subway Tunnel Fires

This paper concerns the smoke control modes and the critical ventilation velocity when the subway tunnel on fires. The standard for the smoke control mode is making sure the smoke exhausting in the shortest way. The critical ventilation velocity means it is just sufficient to prevent the smoke spreading upstream. The critical velocity in different heat release rates obtained though theoretical analysis and computer simulation. In the end, a simple formula to calculate the critical velocity can be fitting out.

Safe Evacuation from Subway Station under Platform Train Fire

The environmental deterioration of the subway station and the safety of the personnel evacuation under platform train fire are researched. The critical fire danger condition is proposed and the time calculation method of evacuation is determined. A platform train fire in a subway station is simulated by the Fire Dynamics Simulator software. Then the available egress time can be got by analyzing the fire temperature and smoke concentration change with time. At the same time, the required egress time is studied through theoretical analysis and computer simulation by software Building Exodus. The results showed that smoke exhaust rate is very important to the smoke control under platform train fire. And the stair evacuation ability is the key to the whole evacuation.

The Carbon Absorb of Cement-Based Material in the Accelerated Carbonation Test

Carbonation is a common influence of cement-based material. And the accelerated carbonation is used in material property modify. With the reaction in the material when carbonating, the carbon dioxide will be solidifying in the material, in the shape of precipitation of calcium carbonate filled the pore. But the ability of the carbon absorbing is unknown, in this paper, some cement-based building materials are took in test, including the aerated brick, cement tile, concrete, and cement mortar. In according to the results, it has found that the carbon absorbing ability is different, and with the carbon absorbing, the strength also increasing. The aerated brick is greatest and the condition of temperature, pressure and reaction time is lowest, which give a reference on the way of the greenhouse gas transform and reduced.

Research on Tensile Bearing Capacity of Self-Drilling Screw Joints for Thick Faced Roof Sandwich Panels

To find out the connection of screw joints and base materials or the metal crest surface at the head of screw which is destroyed first, the tensile bearing capacity of joints between self-drilling screws (SDS) and the base materials were tested first. With two types of SDS joints furnished with C-saddle washers (C-SW) and M-saddle washers (M-SW) respectively, test and analysis on the tensile bearing capacity of SDS joints were undertaken. Corresponding finite element (FE) models were analyzed by ANSYS/LS-DYNA software. Based on mechanical analysis, a new theoretically computational formula for tensile bearing capacity of SDS joints is proposed.

Finite Element Analysis of the Subsidence of Cap Rocks during Underground Coal Gasification Process

This paper discusses the possible surface subsidence and deformation of the overlying rock during the underground coal gasification (UCG) process, which is an important part of feasibility studies for UCG operations. First coal seam roof movement and surface subsidence in the shallow UCG process were simulated by a finite element model coupled with heat transfer module in COMSOL. Numerical results from this model were compared with and in good agreement to the existing studies. This was followed by the development of model for deeper coal seam cases. The comparison of the numerical results from two models shows that surface uneven settlement in deep underground coal gasification is only 7% of that in shallow underground coal gasification.

The Research of Reliability on Recycled Concrete

With the rapid development of urban construction, the waste that construction brings is also increasing. The recycled concrete technology can solve the problems of waste concrete, but also save the natural sand. This paper gives the progress on the research about the reliability of recycled concrete. Because of the rough surface of the recycled concrete aggregates and large porosity, the apparent density, strength and durability of the recycled concrete are different from the ordinary concrete on many aspects. So the study of the reliability about the recycled concrete is very necessary. The page will research on the material subentry coefficient of fifty and sixty years.

The Experiment and Theoretical Analysis of Reusing Waste Cement Mortar

This paper presents the idea of mixing waste cement mortar into foam concrete block, and gets the foam concrete testing models with the values of dry density at 700 to 1000 kg/m3 , and the compression strength at 0.5-2.5MPa, which are met to foam concrete block standard. At the same time, the power formulas for calculating the dry density and compression strength of concrete cubes doped with waste cement mortar have been brought up, which are coincided with the experiment results well. An initial discussion about microcosmic composition has also been given, which has rather high practical application values since it offers experimental and theory foundations for reusing the waste cement mortar. The innovation significance should not be neglected, since it is the first time doing research on these aspects.