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The adequate seismic performance of transportation infrastructures is important for the functioning of the economy and society. This paper focuses on the seismic assessment and analysis of one of the most important components of these infrastructures, the bridges. In this field, nonlinear static procedures (NSPs) have gained significant attention, resulting in different proposals to improve the accuracy of the procedures while keeping their simplicity. The main goal of this study is focused on the evaluation of the applicability of NSPs for irregular reinforced concrete viaducts. A comparative approach is pursued by resorting to (1) the analyses of the performance of three well-known NSPs (N2 method, modal pushover analysis and adaptive capacity spectrum method) and (2) the extension of the scope of previous studies in this field to a more recent method, the extended N2. As such, a set of bridges with different levels of irregularity, configurations and lengths is investigated. The accuracy of different NSPs is evaluated by comparing the results of NSPs with the ones obtained by means of nonlinear dynamic analyses. The comparison of results confirms the acceptable performance of the multi-modal NSPs and highlights the effectiveness of extended N2 method with respect to its simplicity. [ABSTRACT FROM PUBLISHER]

The use of Nonlinear Static Procedures (NSPs) for the seismic assessment of plan irregular buildings is challenging. The most common pushover-based approaches have led to adequate results in regular buildings, and hence, there is a need to verify the validity of such methods on the assessment of irregular structures. In this article, four commonly used nonlinear static procedures (CSM, N2, MPA, ACSM) are applied on the assessment of two existing five- and eight-story plan-asymmetric buildings in Turkey. The accuracy of the different NSPs is evaluated through comparisons with the results derived from nonlinear dynamic analyses. The results are presented in terms of interstory drifts, normalized top displacements, lateral displacement profiles, chord rotations, base shear, and top displacement ratios. The performance of such procedures in evaluating the damage limitation according to the Eurocode8 is also verified. Special attention is given to the ACSM (Adaptive Capacity Spectrum Method) whose performance in 3D plan irregular buildings has recently been tested. Conclusions about the performance of each NSP are outlined at the end of the article. [ABSTRACT FROM PUBLISHER]

Composite joints, considering the composite action of steel and concrete, exhibit, in general, high strength and high ductility. As a consequence, the use of this type of joint has been increasing in many countries, especially in those that are located in earthquake-prone regions. In this paper, a hysteretic model with pinching is presented that is able to reproduce the cyclic response of steel and composite joints. Secondly, the computer implementation and adaptation of the model in a spring element within the computer code Seismosoft is described. The model is subsequently calibrated using a series of experimental test results for composite joints subjected to cyclic loading. Finally, typical parameters for the various joint configurations are proposed. [ABSTRACT FROM AUTHOR]

Though flexible diaphragms play a role in the seismic behaviour of unreinforced masonry buildings, the effect of the connections between floors and walls is rarely discussed or explicitly modelled when simulating the response of such buildings. These flexible diaphragms are most commonly timber floors made of planks and beams, which are supported on recesses in the masonry walls and can slide when the friction resistance is reached. Using equivalent frame models, we capture the effects of both the diaphragm stiffness and the finite strength of wall-to-diaphragm connections on the seismic behaviour of unreinforced masonry buildings. To do this, we use a newly developed macro-element able to simulate both in-plane and out-of-plane behaviour of the masonry walls and non-linear springs to simulate wall-to-wall and wall-to-diaphragm connections. As an unretrofitted case study, we model a building on a shake table, which developed large in-plane and out-of-plane displacements. We then simulate three retrofit interventions: Retrofitted diaphragms, connections, and diaphragms and connections. We show that strengthening the diaphragm alone is ineffective when the friction capacity of the wall-to-diaphragm connection is exceeded. This also means that modelling an unstrengthened wall-to-diaphragm connection as having infinite stiffness and strength leads to unrealistic box-type behaviour. This is particularly important if the equivalent frame model should capture both global in-plane and local out-of-plane failure modes. [ABSTRACT FROM AUTHOR]

Adobe construction represents 5.3% of the total Portuguese building stock according to the latest National Housing Census. The distribution of these adobe buildings is scattered across the country, with higher density in the central region and in Algarve in the south, where the seismic hazard is highest. A large proportion of these buildings are still in use for residential and commercial purposes and are of historical significance, contributing to the cultural heritage of the country. Adobe buildings are known to exhibit low seismic resistance due to their brittle behavior, thus making them vulnerable to ground shaking and more prone to structural damage that can potentially cause human fatalities. Three buildings with one-story, two-stories, and two-stories plus an attic were numerically modeled using solid and contact elements. Calibration and validation of material properties were carried out following experimental results. A set of 30 ground motion records with bi-directional components were selected, and non-linear time-history analyses were performed until complete collapse occurred. Two novel engineering demand parameters (EDPs) were used, and damage thresholds were proposed. Finally, fragility and fatality vulnerability functions were derived. These functions can be used directly in seismic risk assessment studies. [ABSTRACT FROM AUTHOR]

This paper discusses different formulations for calculating earthquake-induced displacement demands to be associated with nonlinear static analysis procedures for the assessment of masonry structures. Focus is placed on systems with fundamental periods between 0.1 and 0.5 s, for which the inelastic displacement amplification is usually more pronounced. The accuracy of the predictive equations is assessed based on the results from nonlinear time-history analyses, carried out on single-degree-of-freedom oscillators with hysteretic force–displacement relationships representative of masonry structures. First, the study demonstrates some limitations of two established approaches based on the equivalent linearization concept: the capacity spectrum method of the Dutch guidelines NPR 9998-18, and its version outlined in FEMA 440, both of which overpredict maximum displacements. Two codified formulations relying on inelastic displacement spectra are also evaluated, namely the N2 method of Eurocode 8 and the displacement coefficient method of ASCE 41-17: the former proves to be significantly unconservative, while the latter is affected by excessive dispersion. A non-iterative procedure, using an equivalent linear system with calibrated optimal stiffness and equivalent viscous damping, is then proposed to overcome some of the problems identified earlier. A recently developed modified N2 formulation is shown to improve accuracy while limiting the dispersion of the predictions. [ABSTRACT FROM AUTHOR]

The purpose of this research is to illustrate, through a case study, a multilevel decision-making process able to support the decision maker in optimizing investment choices for the efficient allocation of public resources, with specific reference to recovery and adaptation to the reuse of unused historical public heritage. During the evaluation process, two methods in particular were combined according to a multiphase design: (i) a multi-criteria analysis to identify the Highest and Best Use among alternative reuse scenarios and (ii) a Discounted Cash Flow Analysis to support verification of the financial feasibility of the investment, in the hypothesis of an enhancement concession in a public–private partnership. Each method was applied in parallel to the evolution of the different design scenarios. The results of the study show that hybrid approaches are a promising line of research in the field of evaluation and urban design, applied to cultural heritage. [ABSTRACT FROM AUTHOR]

This paper investigates the correlation between ground motion parameters and displacement demands of mid-rise RC frame buildings on soft soils considering the soil-structure interaction. The mid-rise RC buildings are represented by using 5, 8, 10, 13, and 15-storey frame building models with no structural irregularity. A total of 105 3D nonlinear time history analyses were carried out for 21 acceleration records and 5 different building models. The roof drift ratio (RDR) obtained as inelastic displacement demands at roof level normalized by the building height is used for demand measure, while 20 ground motion parameters were used as intensity measure. The outcomes show velocity related parameters such as Housner Intensity (HI), Root Mean Square of Velocity (Vrms), Velocity Spectrum Intensity (VSI) and Peak Ground Velocity (PGV), which reflect inelastic displacement demands of mid-rise buildings as a damage indicator on soft soil deposit reasonably well. HI is the leading parameter with the strongest correlation. However, acceleration and displacement related parameters exhibit poor correlation. This study proposed new combined multiple ground motion parameter equations to reflect the damage potential better than a single ground motion parameter. The use of combined multiple parameters can be effective in determining seismic damages by improving the scatter by at least 24% compared to the use of a single parameter. [ABSTRACT FROM AUTHOR]

Repairing and strengthening of existing aged steel-reinforced concrete structures is a major challenge. Today, much of the repair work completed is insufficient and brittle. A promising new solution for repair and strengthening tasks is the use of iron-based shape memory alloy (Fe-SMA). The pre-strained Fe-SMA components enable the pre-stressing of existing building components due to the heat-triggered contraction of the steel. Thus, deflections can be reduced or even recovered. In addition, the cracking process can be adapted, and an improvement in the load, under which the first crack appears, is possible. In this paper, the effects of pre-stress generated by activated Fe-SMA rebars, which were centrally embedded inside of a concrete specimen, are shown. The objective of the study is to quantify the improvement in the loads of the first crack and show the influences of the pre-stressing on the load-bearing behavior and the cracking process. For this purpose, axial tensile tests were performed on concrete bars with height, width, and length of 50 mm, 70 mm, and 900 mm, respectively. These were compared to usual construction steel rebars, pre-strained but nonactivated Fe-SMA rebars, and activated Fe-SMA steel rebars. The evaluation of crack patterns and openings was done using digital image correlation (DIC). The pre-stressing of the concrete causes an increase in the first crack loads of more than 150%, which indicates a clear improvement in the state of serviceability limit. [ABSTRACT FROM AUTHOR]

Seismic assessment is a paramount issue and a valuable instrument towards the conservation of vulnerable structures in seismic prone regions. The past seismic events have highlighted the vulnerability of masonry towers that is exhibited by severe structural and nonstructural damages or even collapses. The preservation of existing structures, mainly focused on the built heritage, is emerging and imposing substantial enhancements of numerical methods, including pushover analysis approaches. The accuracy of the estimated seismic capacity for these structures is correlated with the assumed strategies and approximations made during the numerical modeling. The present paper concerns those aspects by exploring the limitations and possibilities of conceiving pushover analysis in the finite element method environment. The most crucial target is tracing in a pushover capacity curve the corresponding initiation of structural damages, maximum load-bearing capacity, and the ultimate displacement capacity. Different recommendations for achieving this target have been proposed and illustrated for practical utilization. Three representative geometrical towers, adopting three different materials and five different load patterns, are investigated in this study. The load pattern's role and necessity of the displacement-like control approach for the pushover analysis are exploited. This paper highlights the load-bearing capacity overestimation when the force-controlled are implemented. The material model influences the achievement of softening branch with a distinguishable displacement capacity. [ABSTRACT FROM AUTHOR]

A ring footing is found to be of practical importance in supporting symmetrical constructions for example silos, oil storage container etc. In the present paper, numerical analysis was carried out with explicit code FLAC3D 7.0 to investigate bearing capacity of a ring footing on geogrid reinforced sand. Effects of the ratio n of its inner/outer diameter (Di/D) of a ring footing, an optimum depth to lay the geogrid layer were examined. It was found that an intersection zone was developed in soil under inner-side (aisle) of ring footing, contributing to its bearing capacity. Substantial increase of bearing capacities could be realized if ratio n of a ring footing was around 0.6. Numerical results also showed that, bearing capacity of a ring footing could increase significantly if a single-layer geogrid was laid at a proper depth under the footing. Similar contribution was found if a double-layer geogrid was implemented. However, such increases appeared to be rather limited if a triple-layer geogrid or a four-layer geogrid was used. A double-layer geogrid was recommended to increase the bearing capacity of a ring footing; the depth to lay this double-layer geogrid was also discussed. [ABSTRACT FROM AUTHOR]

• Loss estimation methodology for old RC frame-wall building is proposed. • Development of fragility functions of non-ductile RC walls with smooth bars. • Strain penetration deformations taken into account. • High economic losses of building due non-ductile RC walls with smooth bars. This paper deals with the seismic performance and loss assessment of old RC wall-frame buildings in Lisbon, Portugal. These structures are characterised by non-ductile columns and RC walls made with smooth rebars and light transversal reinforcement. They were erected before the introduction of modern seismic codes in the 1980s and represent an important proportion of the city's building stock. The research reported in this paper focuses on the seismic vulnerability assessment of this building typology. An analytical procedure is proposed to estimate the fragility functions of non-ductile reinforced concrete walls with smooth reinforcing bars and light transversal reinforcement, taking into account strength penetration effects. To illustrate the procedure, a case study building is considered. The approach used for the seismic performance assessment adopts component-based fragility and loss functions for the damage assessment of the structural and non-structural drift-sensitive elements, adapted to the Portuguese reality, and a storey-based approach for acceleration-sensitive non-structural elements. The results provide the economic loss of the building as a function of the ground motion intensity level. Finally, results are compared in terms of expected annual losses with other non-ductile RC building typologies. [ABSTRACT FROM AUTHOR]

• Data transfer between two BIMs of the same heritage building was applied. • The two BIMs had different purposes: reconstruction support and facility management. • Position, geometry and attributes transfer followed different strategies. • Availability of a previous BIM instance facilitated the enrichment of the new model. This paper presents and analyses two distinct Building Information Models (BIM) developed for the same heritage building, the Chalet of the Countess of Edla, located in Sintra, Portugal. This building, incorporated in 1995 in the UNESCO's World Heritage List within the Cultural Landscape of Sintra, was severely damaged by fire in 1999, and two distinct BIM-based solutions were developed afterwards, in 2009 and 2020. The instances followed two approaches, the first being a rehabilitation-oriented digital representation, while the second is a centralized resource for building maintenance. In this study the distinct features and characteristics of both models are discussed, highlighting the importance of information transfer from the model set up during the reconstruction to the later, which was surveyed to document the "as-built" construction. An example of this is the complementarity between the two models, which allowed the incorporation of building features, including non-visible constructive elements, from the first model into the management-oriented BIM. [ABSTRACT FROM AUTHOR]

Seismic risk analyses at large scale represents a fundamental support to effective mitigation policies. Evaluating fragility curves able to capture the huge variety of existing buildings is one key point of this analysis. Within this context, this paper proposes a procedure for the evaluation of the fragility curves that aims to limit the computational effort without losing the reliability of the achieved results. This is reached through the execution of a limited number of nonlinear static procedures based on the use of the sensitivity analysis carried out according to the simplified star design with central point approach. The main strength of the procedure is the ability to explicitly quantify the various contributions of uncertainty to the dispersion, associated to those on the structural capacity (taking into account both aleatory and epistemic sources) and on the seismic input. As known, the adoption of a nonlinear static approach for the seismic assessment implies various assumptions, such as the load pattern applied, the criteria adopted to compare the capacity and the demand, and the definition of the damage levels. All these issues potentially affect the reliability of the final fragility curves, which are defined through a proper combination of such various options or they can be selected based on the ones more representative of the expected behaviour of the class. To improve this aspect, the evidences from nonlinear dynamic analyses are used. The feasibility and effectiveness of the procedure is duly demonstrated in this paper through its application to a building stock typology, consisting of existing mixed masonry-reinforced concrete structures, representative of one of the largest portions of the existing residential buildings in Lisbon. The attention is focused only to the global in-plane behaviour by adopting as modelling approach the equivalent frame method, that has been proven particularly efficient and accurate enough in representing the nonlinear behaviour of the examined structures. [ABSTRACT FROM AUTHOR]

This paper focus on the investigation of the behaviour of rubble stone masonry piers, with air lime mortar, loaded in their plane using nonlinear static parametric analysis. This investigation is crucial for the seismic assessment of existing old unreinforced masonry buildings in Lisbon, since there is a clear lack of data for the nonlinear characterization of this kind of masonry. Numerical analyses are performed by adopting the macro-modelling approach implemented in the DIANA software. The adopted procedure for model calibration consists on fitting its behaviour with the results of the performed experimental tests on rubble stone masonry piers with air lime mortar. The parametric analyses are carried out by varying the slenderness and thickness of the piers, as well as the axial load in order to evaluate the influence of such parameters on shear strength, displacement capacity and stiffness. A sensitivity analysis is executed to define the most appropriate size of the elements' mesh. A good agreement is obtained between the piers tested experimentally and its numerical counterpart models in terms of the force-displacement diagram, damage pattern, failure mode and dissipated energy. In addition, the comparison in what concerns both ductility and energy dissipation is also presented for different cases. The results attained by numerical parametric analyses are presented and discussed along with the main conclusions. [ABSTRACT FROM AUTHOR]

The seismic characterization of buildings plays a fundamental role in Portugal since a considerable percentage of the building stock is vulnerable to this phenomenon. It provides reasonable measures which helps to minimize and mitigate the consequences of an eventual seismic event. The paper presents a 3DGIS-based methodology to assess the building seismic vulnerability, based on geometric, structural and material properties for each building, with a focus on the Pombalino buildings. For that purpose, in the first step the data provided by national institutions were organized and stored in a GIS database and applied to build the 3D model, in a procedural modelling approach, and then a simplified seismic risk evaluation methodology was developed and applied to the heritage Lisbon city centre. The followed methodology proved to be very efficient at an urban scale, allowing an easy identification of the vulnerable buildings and the viewing of the surrounding geometries, assisting the interpretation of their spatial distribution. A more detailed study will imply the in situ data collection to calibrate the estimative of fundamental period and to identify structural changes against the officially registered, which are crucial to develop the real assessment of the seismic vulnerability. [ABSTRACT FROM AUTHOR]