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Different qualities of concrete have been fire tested using different geometries of the specimens as well as different load levels and load configurations. The main objective with the study was to examine a test methodology consisting of a full‐scale test and different small scale‐tests for determining the probability of spalling and the amount of spalling of fire exposed concrete structures. A reference specimen was defined as a one‐sided fire exposed slab with the dimensions 1800 × 1200 mm2 giving an exposed area of 1500 × 1200 mm2. A number of concrete qualities with different probabilities for spalling, were tested using the reference specimen. These tests showed that the reference specimens worked well giving the expected test results. Small specimens were manufactured in different shapes with the same concrete as the one used in the reference tests. These small specimens were tested either at the same time as the reference specimens in the large furnace or afterwards on a small‐scale furnace where the fire exposed surface was 450 × 360 mm2. The test results clearly show the increased probability and the increased amount of spalling by using external compressive loading. The results also show that by using pre‐stress through bars or wires the load can be lost due to heating of the bars/wires which results in a decreased amount of spalling. The boundary of the specimen also affects the amount of spalling. The spalling around the edges was in all tests less than the spalling on the central parts of the exposed area. It could also be noted that the spalling did not pass completely through any of the specimens. The reason for this is probably that the water/vapour could migrate out from the unexposed surface of the specimen. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
135.
Jin Wang Marculescu A. Jingshi Li Vorreau P. Tzadok S. Ben Ezra S. Tsadka S. Freude W. Leuthold J. 《Photonics Technology Letters, IEEE》2007,19(24):1955-1957
A technique to overcome pattern dependence in semiconductor-optical-amplifier-based wavelength converters is presented. The technique is based on a careful selection of red- and blue-shifted spectral components having complementary pattern effects in the output spectrum of a wavelength-converted signal. Significant signal quality improvements are reported at a bit rate of 40 Gb/s. 相似文献
136.
Tests and theoretical analysis on the maximum strength of high strength bolted tension flanges joining square hollow section members have been carried out. Yield line theory has been applied in a similar way to that presented in a previous paper. Correlation between test results and theoretical predictions is quite satisfactory. Based on this study, a simple design formula has been proposed. 相似文献
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G. Biallas Dr.‐Ing. C. Sick J. Schneider K.‐H. Trautmann 《Materialwissenschaft und Werkstofftechnik》2007,38(9):705-711
Biaxial fatigue of friction stir welded stiffened panels Within the framework of the European WelAir project, cruciform specimens made from stiffening FSW overlap joints were fatigued in the DLR biaxial test rig. To resemble the loading situation of pressurized fuselage structures, proportional loading without any phase shift, but with different load ratios λ between the loading components in both directions was applied.Natural crack initiation and subsequent crack growth were governed by the stiffness gradient caused by introducing the stringer. Cracks initiated and propagated at run‐in and run‐out locations in a direction perpendicular to the weld seam. The shortest fatigue life was observed for uniaxial loading in welding direction (λ = 0). An additional stress component perpendicular to the joint line (λ > 0) resulted in a higher number of cycles to failure. Similar to single stringer panels, increasing the load ratio also increased the number of cycles to failure for FSW clip‐stringer structural members, but additionally gives a different location of the fatal crack. 相似文献
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