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According to modern seismic codes, in certain cases, the vertical component of the ground motion has to be taken into account. However, no specific instructions concerning the structural modelling—and especially the modelling of vertical masses—are provided. The objective of the present paper is the evaluation of alternative structural models of reinforced concrete slabs under vertical seismic excitation. For this purpose, a series of single-storey buildings were analysed by means of linear and nonlinear time-history analysis and the values of representative response quantities were calculated. The influence of several parameters such as the dimensions and the shape of the slabs, the existence of openings, the distribution of the vertical load, the type of the seismic excitations and the analysis method was investigated. The whole evaluation study led to the derivation of useful conclusions. [ABSTRACT FROM AUTHOR]

For reinforced concrete structures, as beams, slabs or walls, failure under bending is well known and its description and design is relatively internationally agreed. However for the shear failure phenomenon, there is not yet a common agreement at the international level, no consensus is reached on the subject at this time. Many parameters are involved in the shear resistance mechanism and many phenomena coexist. The shear force transfer mechanisms are sometimes complex and difficult to discern. By analyzing the different shear design codes, some shear parameters are taken into account and ignored by others, which makes that a shear effect may be omitted. In addition, different ways are adopted to take into account the different shear parameters. The main purpose of this study is to help the engineering by presenting a comparative study of all the main analytical models for the determination of shear capacity: The EN 1992-1-1:2005 standard (EC2) (CEN, 2005), French National Annex (FD P 18-717, 2013), ACI 318-14 (ACI Committee 318, 2014), fib Model Code 2010 (Fib Model Code 2010, 2012) using level of approximation LoA I and LoA II and (CSA Committee A23.3, 2004) both Modified Compression Field Theory (MCFT) based models, and finally the Critical Shear Crack Theory (CSCT) which is the basis of the Swiss standard SIA 262 (SIA 262, 2003) are all examined. The results obtained are discussed regarding their agreement with eighteen shear experimental results on thick slabs (30 cm, 35 cm, and 40 cm) and thin slabs (10 cm) without shear reinforcement. [ABSTRACT FROM AUTHOR]

The numerical techniques used for blast analysis of structures are categorized in “coupled” and “uncoupled” analysis methods. In a coupled analysis, the fluid-structure interaction is taken into account. Such analysis, although more accurate, is often complex and time consuming. In an “uncoupled” analysis, the blast loads are estimated by empirical equations and then applied to the structure in a separate analysis. Such an analysis is more cost effective, and of more interest for most practical design applications. The main objective of this study is to assess the efficiency of the empirical graphs prescribed by the UFC Code for uncoupled analysis of structures under the nearby air explosions of scaled distances between 0.4 and 0.7 kg/m1/3. The main characteristic of such explosions is the highly nonuniform distribution of blast-reflected pressure on the surface of structure. A method has been developed by the authors to address this nonuniform distribution in the uncoupled analysis. To examine the accuracy of analysis, the response values and the pattern of damages introduced on several reinforced concrete slabs under blast loads are compared with the results of a corresponding coupled analysis, and experimental observations. The uncoupled analysis described in this paper can be reasonably employed in the blast analysis and design of many structures. [ABSTRACT FROM AUTHOR]

This study presents a numerical procedure for the analysis of reinforced concrete slabs (RCS) that obey Nielsen's yield criterion. A pseudo lower bound formulation of finite elements is established to solve the static theorem as a conic optimization problem with the aim to determine the maximum load capacity of RCS. Lower bound solution is improved by means of an adaptive remeshing strategy using a dissipation estimator which is obtained on the normalization of the kinematic criterion defined from the yield criteria. Different known examples are evaluated and the results show a good agreement with the exact values of the collapse load as well as numerical convergence. The displacement rates are estimated from the dual solution established in the optimization problem in order to determine the collapse mechanism in the slab. [ABSTRACT FROM AUTHOR]

Reinforced concrete slabs, just as the other structural elements, are highly affected by the high temperatures. Due to the decrease in strength of reinforced concrete members under high temperature, bearing moment capacity of reinforced concrete slabs also decreases. In this study, a prediction model is investigated in order to determine the bearing moment capacities of reinforced concrete slabs under high temperature. Pre-calculated moment capacities of slabs exposed to fire are predicted by the implementation of adaptive neuro-fuzzy inference system (ANFIS) and the prediction performance of ANFIS model is investigated. The bending capacities of slabs with different concrete characteristics and different times of exposure are calculated. High temperature resulting from the duration of fire exposure is calculated as a function of time in accordance with ISO 834. The temperature distribution inside the slab is determined by the adoption of a steady-state one-dimensional heat transfer. The slab was separated into slim slices and the heat in each slice is determined depending on the time of exposure. Forces and resistance of materials under fire exposure are calculated by applying the reduction coefficients in Eurocode 2. Results confirm the high prediction capability of ANFIS model. [ABSTRACT FROM AUTHOR]