Applied Mechanics and Materials Vols. 284-287

Abstract: Historic buildings and Monuments in the precious historical and cultural heritage plays an extremely important position, with the characteristics of the rare, special and historical value. Over the years in Taiwan, The fire management deficiencies, Cause a fire to become the biggest killer on the destruction of historic monuments. In this study, Explore by referencing and comparing the major fire prevention regulations for historic buildings active and passive fire protection technology around the world, We can find more Active fire protection equipment is widely used . And the use of the superior characteristics of the water mist system in Long-Shan Temple in Lu-Kang, Chang-Hua County as an Empirical research, try to exemplify the way, make appropriate fire use in historic architecture the best program to explore. In conclusion, comparison of the application of various innovative active and passive fire prevention system , and use the appropriate fire prevention technology to design and planning to improve the fire safety for historic monuments and buildings is an important issue. According to the empirical research of “Long-Shan Temple”, we can find water mist technology suitable for historic buildings fire protection in Taiwan.

Abstract: In the current 2005 AISC specification, the in-filled light-weight concrete strength (f_c´) of concrete-filled tube (CFT) columns is set in the range of 21~ 42 MPa, but with no real substantial testing data to confirm and verify the provisions. Research work related to rectangular column sections with light-weight concrete is rather limited and deserves further investigation. Eighteen rectangular tubes filled with light-weight concrete with f_c´ varying from 21.4 to 43.5 MPa were tested. A special kind of light weight aggregate using find sediment deposits dredged from a local reservoir in Taiwan were used in this experimental study. Formulas for CFT columns as specified in the design code AISC Specification were examined and compared. The test results actually show that the further lower f_c´ values are possible and that the 1999 AISC-LRFD provisions yields conservative design results. For the f_c´ range specified in the 2005 AISC specification is found to be in good agreement with the test results

Abstract: A study on the structural performance of the tensioning air beam system (TABS) is presented. TABS consists of the air beam, steel frames and cable struts and is a hybrid structural system. This system has the advantage of reduced self-weight and is easy to construct while it can improve the load bearing capacity of membrane structures. It maximizes the structural capacities of individual elements, thus can be considered as a very effective system in both structural and economical aspects. In this study, a structural test was carried out to investigate the structural performance of TABS under different membrane pressure conditions. A simple analytical model was proposed to predict the structural behavior of TABS and its validity was evaluated by comparing its results with the test values.

Abstract: Concrete filled steel tube has been consistently used in tall buildings as it represents excellent structural performance and economical efficiency compared with other structural systems. The use of high strength steel in concrete filled steel tube can reduce the column size and increase the effective space in the buildings. But, the limit of width-to-thickness ratio to prevent local buckling is an obstacle to applying the high strength steel as it considerably decrease following to the strength increase. This paper addresses the effect of steel plate slenderness limit on the compression behavior in 800 MPa Grade steel. Four short column specimens were tested under axial compression. Main test variables were width-to-thickness ratio and shape of section. Test results were analyzed in the viewpoint of local buckling strength, yield strength, maximum strength and plastic deformation capacity of specimens. The experimental results showed that all specimens exceeded the maximum strength of calculated value by design code and represented similar deformation capacity regardless of width-to-thickness ratio. So, the limit of width-to-thickness ratio in high strength steel could be amended less strict.

Abstract: In the design procedure of the cooling tower the form-finding of the shell is the most important process, because the shape of the shell determines the sensitivity of dynamic behavior of the whole tower against wind excitation. The purpose of the study is the investigation of the influences of the geometric parameters of the cooling tower shell on the structural behavior. The geometric parameters - height of throat, angle of base lintel and radius of top lintel - were analyzed in detail. In the linear analysis the influence of each geometrical parameter will be evaluated by the required amount of the reinforcement steel. The realistic behaviours of the towers with various geometries, found out by geometrically and physically non-linear analysis, will be discussed in detail. Each geometry parameter influence will be evaluated by the comparison of the damage index developments in the tower under increasing wind effect. Herein a damage indicator is defined by means of the modal parameters; natural frequencies and mode shapes varying according to the damage state. As a result, a hyperbolic rotational shell with the small radius overall will yield the shell geometry with a higher first natural frequency and thus a wind-insensitive structure. Linearly and nonlinearly numerical simulations demonstrate influence of the shell-geometric parameters on structural behaviours. The results of this study may be informative for the form-finding of the cooling tower shell.

Abstract: In recent years, the T-Headed bar has been gradually applied to bridge and building structures. However, until Year 2008, a debut of the headed bar in the ACI 318 Design Code was found. There were six limitations on materials’ strength properties, bearing area of head and concrete-cover thickness and spacing of the reinforcement with the head to be made in the Section 12.6 of the ACI 318-08 Code. This paper concerns some issues that were difficult application for the practical engineering or had potential to be improved. They include the clear spacing of the headed bars not less than 4 times the diameter of the bars, the bearing area of head of the headed bar not less than 4 times cross-sectional area of the bars and concrete limit on normal-weight and its effective compression strength not more than 42 MPa. In this study, a total of 43 specimens with a CCT node (Compression-Compression-Tension Node) experimental model were conducted to evaluate anchored performance of the headed bars. Study parameters in this work included strength of concrete, size of reinforcement, bearing area of T head, spacing of bars and confinement condition provided by horizontal reinforcement. Additionally, some benchmark specimens those placed straight bars, and standard 90º and 180º hook bars were carried out for comparison. Test results showed that for anchorage performance, the T-headed bars could provide better than the standard 90º and 180º hook bars. Test results also indicated that the headed bars with head bearing area of three times sectional area of the bar were able to perform as well anchored behavior as their head bearing area with four times sectional area of the bar. In addition, comparing the test results of specimens their spacing having 1.5 and 4 times diameter of the bar, it was found that their anchored strength capacities were similar.

Abstract: A combined heating and cooling system was developed and the system performance was simulated by a mathematical model. This is a building integrated system whereby the facade is used as a solar collector. The system consists of two cavities, i.e. the air is heated throughout the Cavity 1 whereas the air in Cavity 2 is cooled via indirect evaporative cooling. The simulation study used weather conditions of London for a south-facing façade with plate area of 40m2; and followed by a simple economic analysis for the system. Space heating is needed for most of the months, however cooling is more favorable for the months of June, July and August. It is estimated that present system is able to give an annual energy saving of 10,877kWh, which is equivalent to 5,874kgCO2/year of emission avoidance. Moreover, it is cheaper compared to the conventional solar flat plate air heaters. For a discount rate of 5% and 30 years of lifetime, the economic analysis found that the total system cost is approximately £4,952, which gives a payback period for less than a year.

Abstract: The axial stiffness of the corrugated steel plate is negligible by nature of unique geometric characteristics of the plate called as the accordion effect. This unique effect results in high efficiency on post-tensioning. Thus, corrugated steel plate is very suitable for a web of PC-box girder. Recent researches show that strain and stress in sub-panel of corrugated steel webs, that are induced by local bending of the sub-panel, exist even if the axial stiffness is negligible. These strain and stress in sub-panel are important since it might cause fatigue failure of the structure under repeated loading. This study presents the analytical simulation of the accordion effect of the I-girder with corrugated steel webs under pure axial load or bending including the effect of local bending of sub-panel of the corrugated steel webs. Theoretical study and numerical results were combined to develop the simplified equation to evaluate the accordion effect including the effect of local bending of the sub-panel.

Abstract: Following the nuclear power plant accident in Fukushima Japan, seismic capacity evaluation has become a crucial issue in combination building safety. Condensate storage tanks are designed to supplies water to the condensate transfer pumps, the control rod drive hydraulic system pumps, and the condenser makeup. A separate connection to the condensate storage tank is used to supply water for the high pressure coolant injection system, reactor core isolation cooling system, and core spray system pumps. A condensate storage tank is defined as a seismic class I structure, playing the important role of providing flow to the operational system and the required static head for the suction of the condensate transfer pumps and the normal supply pump. According to the latest nuclear safety requirements, soil structure interaction must be considered in all seismic analyses. This study aims to rebuild the computer model of condensate storage tanks in Taiwan using the SAP 2000 program in conjunction with the lumped mass stick model and to evaluate the soil structure interaction by employing the SASSI 2000 program. The differences between the results with the soil structure interaction and spring model are compared via natural frequency and response spectrum curves. This computer model enables engineers to rapidly evaluate the safety margin of condensate storage tank following the occurrence of earthquakes or tsunamis.

Abstract: Prediction of structural behaviour by numerical modelling can reduce the cost in conducting full-scaled experiments. This paper studies the stiffness and strength behaviour of top-seat flange-cleat connection for cold-formed steel double channel sections using finite element method. In this investigation, cold-formed channel sections are assembled back-to-back to form I-shape beam and column members. The 2 mm cold-formed bracket and 6 mm hot-rolled angle are used to connect the members. The results were collected from different beam depth ranged 150 mm, 200 mm and 250 mm. The rotational stiffness and strength obtained from the numerical modelling are then compared to the design requirements from BS EN 1993-1-8 and experimental data. The comparison of moment-rotation behaviour for top-seat flange-cleat connection has shown not more than 35% difference for strength behaviour and 50% difference for rotational stiffness behaviour between numerical modelling and experimental data. However, there is a noticeable difference between finite element models and analytical calculation. The differences are recorded from 18% to 65% for strength behaviour and between 1% and 153% for stiffness behaviour. The differences obtained between finite element analysis and experimental investigation are caused by edge stiffener while differences from finite element models and analytical models are due to strain hardening.