The behaviour of reinforced concrete slabs in fire

In this paper a robust model is presented based on the previous layer procedure developed by the author to also take into account the effects of concrete spalling on the behaviour of concrete slabs under fire conditions. In this study, a detailed analysis of a uniformly loaded reinforced concrete slab subject to different degrees of concrete spalling under a standard fire regime is first carried out. Further, a series of analysis of floor slabs with different degrees of concrete spalling is also performed on a generic reinforced concrete building. A total of 16 cases have been analysed using different degrees of spalling on the slabs, with different extents and positions of localised fire compartments. It is clear that adjacent cool structures provide considerable thermal restraint to the floor slabs within the fire compartment. And it is evident that the compressive membrane force within the slabs is a major player in reducing the impact of concrete spalling on the structural behaviour of floor slabs in fire. (C) 2010 Elsevier Ltd. All rights reserved

Development of a creep-free stress-strain law for fire analysis of steel structures

© 2015 John Wiley & Sons, Ltd.This paper presents a practical procedure for obtaining creep-free stress-strain laws for steel exposed to fire, on the basis of codified stress-strain laws that consider creep implicitly. The applicability of the proposed procedure has been tested on two commonly used stress-strain laws for steel at elevated temperature, the Eurocode 3 law and a Ramberg-Osgood model, both of which have implicit consideration of creep. The simulation of two published steel coupon experiments on steel of grades S275 and S355 shows that both the Eurocode and Ramberg-Osgood stress-strain laws produce inaccurate predictions of creep in fire at elevated temperatures. The proposed procedure was thereby used to extract the implicit creep according to the heating rates of the transient coupon tests and to derive the creep-free stress-strain laws. It has been shown that, by combining the creep-free stress strain law obtained by the proposed methodology with an explicit creep model, a more realistic prediction of steel behaviour in the selected coupon test studies can be achieved

Extension of tabulated design parameters for rectangular columns exposed to fire taking into account second order effects and various fire models

Fire, as one of the most severe load conditions, has an important impact on concrete structures. It does not only affect the material strength, but also the structural stiffness and stability. A concrete column, compared to other structural members, has most often to cope both with vertical forces and bending moments transmitted by slabs and beams. Consequently, it is essential to find a reliable and practical way to establish interaction curves for the overall structural behaviour of concrete columns subjected to fire. In this paper, a cross-section calculation method based on the material models of Eurocode 2 is explained and adopted to calculate interaction curves for a typical rectangular column exposed to the ISO834 standard fire. Subsequently, an iterative approach is introduced to develop interaction curves taking into account second order effects in case of four-side heated fire exposure. The maximum permitted slenderness ratios of columns under different fire durations are obtained and compared with Eurocode 2 provisions. Finally, this method is applied to calculate the maximum permitted slenderness ratios for columns exposed to hydrocarbon fires and natural fires

Effects of juice pH and potassium on juice and wine quality, and regulation of potassium in grapevines through rootstocks (Vitis): a short review

In warm irrigated regions of Australia (such as Sunraysia), pH of grape juice often tends to be high (e.g. > 3.8). A high juice pH is undesirable for the production of quality wines as it results in wines of low quality for example, reduced colour stability and poor taste. Such a high juice pH is typically associated with a high concentration of K in the juice, depending on  the scion, rootstock and location. Potassium is an essential nutrient and plant genotypes, including grapevines, differ in the accumulation of K in plant and/or plant parts. This difference in the accumulation of K by genotypes can be exploited to manipulate the concentration and content of K in plants, berries in particular for example, through selection and use of low K accumulating rootstocks to overcome the high pH affects. This paper briefly reviews the effects of juice pH and on juice and wine quality, and the role and effect of rootstocks in the regulation of K in grapevine. This will provide a basic knowledge about the current research and key future research needed for the maintenance of acceptable quality of grape juice and wine through use of rootstocks.

Effects of juice pH and potassium on juice and wine quality, and regulation of potassium in grapevines through rootstocks (Vitis): A short review

In warm irrigated regions of Australia (such as Sunraysia), pH of grape juice often tends to be high (e.g. > 3.8). A high juice pH is undesirable for the production of quality wines as it results in wines of low quality for example, reduced colour stability and poor taste. Such a high juice pH is typically associated with a high concentration of K in the juice, depending on the scion, rootstock and location. Potassium is an essential nutrient and plant genotypes, including grapevines, differ in the accumulation of K in plant and/or plant parts. This difference in the accumulation of K by genotypes can be exploited to manipulate the concentration and content of K in plants, berries in particular for example, through selection and use of low K accumulating rootstocks to overcome the high pH affects. This paper briefly reviews the effects of juice pH and on juice and wine quality, and the role and effect of rootstocks in the regulation of K in grapevine. This will provide a basic knowledge about the current research and key future research needed for the maintenance of acceptable quality of grape juice and wine through use of rootstocks

MEDIATOR FOR INTEGRATION TESTING

The subject technology provides a software infrastructure that makes it easy to write integration tests for applications and related back-end processes that utilize services over a network (e.g., web applications, operating systems, mobile applications, browsers, etc.) to, for example, improve automation coverage and prevent certain security issues. A Mediator component provides a mechanism for connecting disparate infrastructures to allow applications and/or devices under test to utilize and communicate with processes that would not normally be available during integration testing

An approach for evaluating vulnerability of bridges against fire hazard

In recent years, bridge fires are becoming a growing concern, however there is no specific requirements in codes and standards for design of bridge structural members against fire hazard.This paper presents an approach fordeveloping an importance factor for design of bridges against fire hazard.The proposed importance factor takes into account the degreeof vulnerability of a bridge to fire and also the critical nature of a bridge fromtraffic functionality point. The proposed importance factor for fire design, which is similar to the one currently used for evaluating wind, and snow loading in buildings,is validated against previous bridge fire incidents. It is shown through this validation that the proposed method for importance factor can be used as a practical tool for identifying critical bridges from the point of fire hazard and also to develop relevant design strategies for mitigating fire hazard in bridges

Effect of load on thermal spalling of reinforced concrete containing various mineral admixtures

The present experimental program was planned to investigate the effect of type of mineral admixture, pre-load and the presence of confining reinforcement on the spalling behaviour of heated high performance concrete (HPC). Reinforced concrete cylindrical short columns were cast and exposed to four different target temperatures. A compressive preload equal to 25% of the ultimate load capacity of column was maintained on the specimens during heating and cooling. The test results mainly focus on the influence of above said variables on spalling behaviour of reinforced HPC columns. Interesting observations have been made in the paper on the subject matter of the workshop

TRM versus FRP in flexural strengthening of RC beams: behaviour at high temperatures

The flexural behaviour of RC beams strengthened with TRM and FRP composites was experimentally investigated and compared both at ambient and high temperatures. The investigated parameters were: (a) the strengthening material, namely TRM versus FRP, (b) the number of strengthening layers, (c) the textile surface condition (dry and coated), (d) the textile material (carbon, basalt or glass fibres) and (e) the end-anchorage of the flexural reinforcement. A total of 23 half-scale beams were constructed, strengthened in flexure and tested to assess these parameters and the effectiveness of the TRM versus FRP at high temperatures. TRM exhibited excellent performance as strengthening material in increasing the flexural capacity at high temperature; in fact, TRM maintained an average effectiveness of 55%, compared to its effectiveness at ambient temperature, contrary to FRP which totally lost its effectiveness when subjected to high temperature. In specific, from the high temperature test it was found that by increasing the number of layers, the TRM effectiveness was considerably enhanced and the failure mode was altered; coating enhanced the TRM effectiveness; and the end-anchorage at high temperature improved significantly the FRP and marginally the TRM effectiveness. Finally, the formula proposed by the Fib Model Code 2010 was used to predict the mean debonding stress in the TRM reinforcement, and using the experimental results obtained in this study, a reduction factor to account for the effect of high temperature on the flexural strengthening with TRM was proposed