K.A. Cashell

The use of vehicle acceleration measurements to estimate road roughness

Road roughness is a broad term that incorporates everything from potholes and cracks to the random deviations that exist in a profile. To build a roughness index, road irregularities need to be measured first. Existing methods of gauging the roughness are based either on visual inspections or using one of a limited number of instrumented vehicles that can take physical measurements of the road irregularities. This paper proposes the collection of data from accelerometers fixed in a specific vehicle type and the use of this data to estimate the road condition. Although the estimate is approximate, accelerometers are being increasingly used by car manufacturers to improve suspension performance and the proposed method is relatively inexpensive to implement and provide road managers with constantly updated measurements of roughness. This approach is possible due to the relationship between the power spectral densities of road surface and vehicle accelerations via a transfer function. This paper shows how road profiles can be accurately classified using axle and body accelerations from a range of simulated vehicle–road dynamic scenarios.

Failure Assessment of Lightly Reinforced Floor Slabs. I: Experimental Investigation

This paper is concerned with the ultimate behavior of lightly reinforced concrete floor slabs under extreme loading conditions. Particular emphasis is given to examining the failure conditions of idealized composite slabs which become lightly reinforced in a fire situation as a result of the early loss of the steel deck. An experimental study is described which focuses on the response of two-way spanning floor slabs with various materials and geometric configurations. The tests enable direct assessment of the influence of a number of key parameters such as the reinforcement type, properties, and ratio on the ultimate response. The results also permit the development of simplified expressions that capture the influence of salient factors such as bond characteristics and reinforcement properties for predicting the ductility of lightly reinforced floor slabs. The companion paper complements the experimental observations with detailed numerical assessments of the ultimate response and proposes analytical mode...

Failure assessment of lightly reinforced floor slabs. II: Analytical studies

This paper describes numerical and analytical assessments of the ultimate response of floor slabs. Simplified analytical models and finite-element simulations are described and validated against the experimental results presented in the companion paper. The simplified analytical model accounts for membrane action and the underlying mechanisms related to failure of floor slabs by either reinforcement rupture or compressive crushing of the concrete. In this respect, the significant influence of material properties, including bond strength, is considered in the model and described in detail. A detailed nonlinear finite-element model is also employed to provide further verification of the simplified approach and to facilitate further understanding of the overall response. The results and observations of this study offer an insight into the key factors that govern the ultimate behavior. Finally, the models are applied under elevated temperature conditions to demonstrate their general applicability and reliability.

Ductility of composite floor slabs under idealised fire conditions

This paper is concerned with the ductility of composite floor slabs under extreme loading conditions. Although the consideration given to the assessment of ductility is of general relevance to various applications, it is of particular significance to conditions resembling those occurring during severe building fires. The main purpose of the study is to examine the failure of composite floor slabs which become lightly reinforced in a simulated fire situation owing to the early loss of the steel deck. An account of the main results from 15 large-scale tests on simply supported slab specimens is presented. A simplified expression for predicting the ductility of this type of member is proposed, after calibration and validation against the experimental results and more detailed analytical relationships. The experimental results and observations enable a direct assessment of the influence of a number of important parameters, such as the reinforcement type, properties and ratio on the ultimate response. The test...

Experimental Assessment of Ferritic Stainless Steel Composite Slabs

This paper describes investigations into the structural behaviour of ferritic stainless steel floor decking in composite construction. Although commonly used in the automotive and industrial sectors, structural applications of ferritic stainless steels are rare owing to a relative lack of knowledge, performance data and design guidance. These materials display considerably better atmospheric corrosion resistance than carbon steels, as well as having good ductility, formability and excellent impact resistance. As part of a wider investigation into the use of ferritic stainless steels in structural applications, an experimental study has been undertaken to assess the viability of using these materials for the profiled decking in composite floors. The shear connection behaviour between the steel beams and the composite slab is clearly critical and this is influenced by the through-deck welding process of the shear connectors. The practicality of this welding technique is assessed and described in this paper. Furthermore, the results of a series of push tests are presented. These enable the resistance of the shear connectors to be established and compared with the strengths specified in EN 1994-1-1 for composite slabs using galvanized steel decking.