This open access book presents a methodology for the assessment of structural building details, taking into account the contemporary guidelines for earthquake-resistant and energy-efficient ...buildings. A review of structural details for energy-efficient buildings revealed that in some cases the structural system is interrupted, leading to solutions which are not suitable for earthquake-prone regions. Such typical examples would be the use of thermal insulation under the building foundation and reduction of the load-bearing elements’ dimensions – also at the potential locations of plastic hinges which are crucial for the dissipation of seismic energy. The proposed methodology of assessment favours a collaboration of architects, engineers, contractors and investors in the early stage of building design. By this the methodology enables efficient decision-making and contributes to a selection of optimal building structural details. The book starts by presenting the typical structural details of the thermal envelope of energy-efficient buildings together with the scientific background required for understanding the process of detail development from all the relevant aspects. Over 20 examples of most frequent details are described and analysed to raise awareness of the importance of earthquake resistance, sustainability, energy-efficiency and thermal comfort for users.
In parallel with the observed greater frequency of natural disasters worldwide, there has been an ever-increasing interest in urban resilience and its assessment. Experience obtained in recent ...extreme events (in particular, earthquakes and floods) has revealed that both the level of preparedness and the response of affected cities were insufficiently high, whereas the recovery process was long and expensive. For this reason improved pre-disaster mitigation actions, as well as smart and strategic urban planning in threatened areas (e.g. in earthquake-prone regions), is essential. For this purpose, a comprehensive review of the existing literature has been performed in relation to the holistic assessment of urban system resilience to natural disasters, with an emphasis on the effect of earthquakes. The main goal of the review was to try to determine how to best assess the resilience of urban systems as a whole, taking into account all of their components, i.e. both the physical components (i.e. of buildings, infrastructure, and open spaces) and the social components (i.e. of the community), as well as the dynamic interactions between them. Besides considering the commonly measured indicators (e.g. determination of the scope of actual structural damage caused by an earthquake), the paper tries to extend the discussion to some indicators which are not so commonly taken into account, by applying a quantitative resilience assessment approach. Based on the results of the described new literature review, a preliminary concept which could be used to assess the seismic resilience of complex urban systems, taking into account all urban components which have been identified as having an important impact on the latter, is presented. This concept consists of three different parts: (i) a probabilistic fragility analysis for each individual physical element (i.e. a building or an infrastructure element), (ii) a composite index methodology for the measurement of community disaster resilience, and (iii) a complex network approach (graph theory) for the assessment of the resilience of urban systems as a whole. Since, in the existing literature, there is a lack of consideration of urban open space, which can have a significant role in the recovery process, it is suggested that, in future research of seismic resilience assessment, such open space should be taken into account, and that an in-depth study of possible recovery strategies be performed.
The paper tries to contribute to a better understanding of the behaviour of base isolated asymmetric structures. Numerous variants of originally symmetric four storey RC frame building isolated by a ...simple lead rubber bearing base isolation system with various distributions of isolators were considered as test examples. The symmetrical structural variant and appropriate LRB bearing properties were designed according to Eurocode 2 and 8. The asymmetric variants were produced by shifting the centre of mass CM toward one side of the building. Additional “torsionally unrestrained” and “torsionally restrained” sub-variants of each building variant were obtained by changing the mass distribution, while total mass sum remained unchanged. For the base isolation system we have considered six different distributions of bearings characterized by the position of the centre of isolators CI in respect to the centre of mass CM of the superstructure. Two symmetric (Uniform and Peripheral distribution) and four asymmetric distributions of isolators (called CI = CM, CI = CM/2, CI = −CM/2 and CI = −CM) were included in the analyses. The paper analyses the positive and negative effects of different bearing distributions to the displacements and rotations of the superstructure as well as to the base isolation system and tries to determine the most favourable distribution of isolators that is able to balance the effects of introduced eccentricities. The results obtained by 3D nonlinear dynamic analyses are presented as an average of maximums for ten selected ground motions and three different scalings. They indicate that all six considered distributions of bearings, however differently, substantially reduce the unfavourable torsional effects, which are with different extent transferred from the superstructure to the base isolation system. It was further observed that CI = CM distribution, favoured by common building codes, is best only for accommodating the torsional effects in the base isolation system. A significantly different conclusion was found observing the nonlinear behaviour of the superstructure, where CI = CM distribution might cause more damage in the flexible side frames.
In this study the effects and costs of implementing a base isolation system for the mitigation of the seismic risk of an existing externally-braced steel frame rack structure are analysed by means of ...nonlinear static (pushover) analysis. Various plan asymmetric variants, with different realistic distributions of the payload mass and occupancy levels, have been investigated under two seismic intensities. The results obtained are presented as floor plan projection envelopes of the top displacements and as plastic hinge damage patterns of the superstructure. In the presented cost evaluation, the cost of the implementation of the proposed base isolation system is compared with the estimated costs of structural repairs to the damaged structural members of the superstructure, as well as with estimated expenses of the downtime period and content damage. The results have shown that base isolation is, in general, not economically feasible for lower ground motion intensities, whereas it could be of great benefit in the case of moderate and high intensities. A simple rough cost estimation study, based on the obtained plastic hinge patterns, showed that the inclusion of the downtime period costs and content damage costs might be important parameters, which — if taken into account — could make such an isolation system viable also for lower ground motion intensities. The other benefits brought by seismic isolation, such as savings on the building design costs, reductions in the threat to employees’ lives, and others, were, however, not included in the presented study. The comparison is done only for two deterministic scenarios of seismic attack, e.g. for design ground motion intensity (
a
g
=0.175 g) and for increased intensity with
a
g
=0.25 g indicating the Maximum Considered Earthquake level.
Historic masonry buildings often require structural repair or retrofit to attain a satisfactory level of seismic resistance. This paper analyses the effect of externally bonded fibre-reinforced ...polymer (FRP) retrofitting systems on the global seismic response of such buildings in order to achieve the fundamental code-based requirements that refer to the structure's state of damage for a specified limit state. As a case study, a three-storey historic unreinforced masonry (URM) building was selected. The first part of the paper presents an FRP design procedure for determining which vertical structural elements should be retrofitted and to what extent. As a result, six different FRP retrofitting layouts have been selected and analysed with the aid of non-linear static analyses in the second part of the paper. The paper concludes with a cost-feasibility study by introducing a cost-effectiveness index for FRP reinforcement that identifies the effectiveness of an FRP layout by accounting for the amount of retrofitting material used and comparing it with its effectiveness in improving the global seismic resistance.
A framework is proposed in which certain well-known concepts of statistical mechanics and thermodynamics can be used and applied to characterize structural systems of interconnected Timoshenko beam ...elements. We first make the assimilation to a network of nodes linked by potential energy functions that are derived from the stiffness properties of the beams. Then we define a series of thermodynamic quantities inherent to a given structure (i.e., internal energy, heat, pressure, temperature, entropy, and kinetic energy). With the exception of entropy, all of them have the dimensions of energy. In order to test this new framework, a series of experiments was performed on four structural specimens within the elastic regime. Their configurations were taken from the seismic regulations known as Eurocode 8 in order to have a better based reference for our comparisons. The results are then explained within this new framework. Very interesting correlations have been found between the parameters given in the code and our concepts.
This work applies the variational principles of Lagrange and Hamilton to the assessment of numerical methods of linear structural analysis. Different numerical methods are used to simulate the ...behaviour of three structural configurations and benchmarked in their computation of the Lagrangian action integral over time. According to the principle of energy conservation, the difference at each time step between the kinetic and the strain energies must equal the work done by the external forces. By computing this difference, the degree of accuracy of each combination of numerical methods can be assessed. Moreover, it is often difficult to perceive numerical instabilities due to the inherent complexities of the modelled structures. By means of the proposed procedure, these complexities can be globally controlled and visualized in a straightforward way. The paper presents the variational principles to be considered for the collection and computation of the energy-related parameters (kinetic, strain, dissipative, and external work). It then introduces a systematic framework within which the numerical methods can be compared in a qualitative as well as in a quantitative manner. Finally, a series of numerical experiments is conducted using three simple 2D models subjected to the effect of four different dynamic loadings.
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