Applied Mechanics and Materials Vols. 90-93

Abstract: Based on ABAQUS software platform, the author analyzed the concrete beam’s temperature field by the finite element numerical simulation technology,and got the temperature field and the measuring temperature-time curve for the beam of different sections.The calculated results made a perfect coincide with on-site test ,which proved that ABAQUS simulated temperature field of concrete component has certain precision .Thus, the results provided the references for those who want to do more in-depth studies of the concrete beam’s mechanical properties after fire and reinforcement design.

Abstract: Disaster degree and hazard risk of rockfall is essential for roadside slope design for safety. This paper is concerned with research efforts to calculate full motion trace of the rockfall along road slope with effective and numerical analysis methods. Two main terms including gradient of side slope and damping function between rockfall, mountain slope and rock speed are employed in so-called Damping and Rebounding Osculation Method (DROM). This tool is developed to define rock motion trace and delve into motion characteristics such as direction and rotational angle speed of the rockfall. Hereon, polygon rock is regarded as a rigid body of Non-particle and the motion formula are set up with the revolution motion of rock rigidity. The objective of this study is to accurately characterize the rockfall motion trace for disaster prevention and mitigation.

Abstract: Much research has been directed at the progressive collapse of the over-ground structures under free air burst loading in recent years, while less work has been stressed on the progressive collapse of the underground structures, which subjected to internal blast loading. A proposed method is presented in this paper to simulate the progressive collapse of one underground reinforced concrete frame under internal blast loading, which is using LS-DYNA. The numerical results indicate that the proposed method is more accurate and timesaving, compared with alternative load path method (ALPM) and direct simulation method (DSM).

Abstract: Four PVC pipes with the length of 1500 millimeters and inner diameter of 160 millimeters were used to make a consolidation device with a drainage system at the bottom, in order to make a study on the relationship between surface sedimentation and water discharge with time at different heights (the heights were adopted as 150 millimeters, 250 millimeters, 300 millimeters, 350 millimeters respectively) of red mud tailings of Pingguo Aluminum. A test was conducted on the mud discharge of the first layer and second layer respectively. It is shown that when the red mud is discharged at the first layer and the second layer, the sedimentation of which increases with the increase of height. The sedimentation curves of the first layer with 300mm, 350mm heights and the second layer emissions have two turning points. The red mud sedimentation rate of the height of 300mm is faster than the other three and the gap of the water discharge between heights of 250 millimeters and 300 millimeters is about 100 gram. The water discharge of the second layer is smaller than the first layer, of which the gap is about 250 gram; the decreasing rates of the red mud void ratio of the first layer and the second layer are the same, but the decreasing speed of void ratio of the first layer emissions is much faster, and the final void ratio tends to be between 1.22 ~ 1.26; The density curve experiences two processes of increase and two processes of decrease after the mud of first layer and second layer are discharged respectively, then tends to be stable and the stable value is between 2.01 and 2.06 g/cm³.

Abstract: Earthquake codes have been revised and updated in recent years. The issue and implementation of the guidelines for seismic design of bridges have attracted interests and attentions of many researchs at home and abroad. The most important aspect of the code rests on its main approach incorporating “performance-based seismic design”. The main purpose of this study is to investigate the differences caused by the use of guidelines for seismic design of highway bridges and Eurocode8 for bridges in performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers. The differences in expressions and some important points for performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers by codes are briefly illustrated in tables and figures. Based on the lessons learned from significant earthquakes in the last few years, the existing problems of the current code are pointed, and the trends of future study are discussed.

Abstract: Acoustic emission technique is a non-destructive detection method that can continuously and dynamically detect the damage evolution inside the structure. In this paper, a local fire experiment is conducted within an entity building to acquire and analyze acoustic emission parameters in the whole process of the experiment. Results show that the number of events is closely related to the crack development, the peak value of the energy rate occurs when a large number of cracks appear, signals with the amplitude less than 80db account for more than 90%, signal amplitudes produced by the building damage in different stages from fire development to fire attenuation are different, and most signals with the amplitude of 75db – 85db are produced in the stage of fire development.

Abstract: Nowadays the mechanical properties of epoxy resin used to paste CFRP strengthening the concrete structures, has a sharp drop in more than 60°C. Four CFRP-strengthened concrete one-way slabs were studied in the fire, one using epoxy resin and the other three using inorganic adhesive (Magnesium Oxychloride Cement). The experimental results show that :(a) The fire resistance performance of CFRP-strengthened concrete slab by inorganic adhesive with 15mm thickness fire protection was better than the slab without fire protection; (b) Without considering the impact of burst, the fire resistance performance of CFRP-strengthened concrete slab by inorganic adhesive with 30mm fire protection was better than the slab with 15mm fire protection;(c)Under the same fire protection measures, the fire resistance performance of CFRP-strengthened concrete slab with inorganic adhesive was better than the concrete slab strengthened with CFRP by epoxy adhesive.

Abstract: Malaysia is considered as a very low seismic region country. However countries that border Malaysia such as Indonesia and Philippines are the two most seismically active countries with frequent earthquakes. The close proximity of these countries means that Malaysia is prone to risk of distance earthquakes. As such, anticipated problem associated with earthquakes must be dealt with. There is several problems expected need to be justified in this disaster phenomenon. Area of higher risk to be affected by earthquake need to be identified. To date, many building in Malaysia are not designed to withstand seismic load which means that they are susceptible to collapse in the event of earthquakes. School buildings contain large numbers of public user during most of the times. A sustainable approach of visual assessment and detailed analysis are needed to ensure the school building sustainability towards an earthquake threat. An ATC-21 evaluation and a finite element analysis were performed on a 4 storey standard school building in order to evaluate its performance should it be subjected to seismic waves. Results from the analysis were used to compare with the structures actual capacity and a potential improvement to the building can be identified. The assessment methods engaged no destructive in-situ test and the cost involved in the assessment are kept to a minimum. The final outcome of the study produces a guideline and database that served as a potential maintenance proposal and reference for engineering community in the future.

Abstract: In this paper, three kinds of single frames including 6, 8 and 10 stories are presented using LS-DYNA software, the stability of structure is studied due to the bottom side column demolition. The results show that the more structure floors, the more side span cantilever structure system collapses. The damage of the junction with the main structure is due to gravity bending moment. The main structure swings back and forth in horizontal direction and damage in some parts of the frame. The more floors, the more the period t of range of main structure movement is longer.

Abstract: To study the application of E shaped steel bearing on the simply supported beam bridge, the Xinhua bridge is analyzed by the nonlinear time-history method and the Midas/Civil software, considering the interaction between pile and soil. The related data are obtained through two computational models. And the data are compared in this paper. The results show that the bending moments and shear forces of the bottom of the fixed pier are reduced, due to using the E shaped steel bearing at the fixed pier. The E shaped steel bearing dissipates the earthquake energy and reduces the earthquake response of the bridge.