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In reinforced concrete (RC) multi-storey buildings, the important role of the seismic interaction of structural frames with masonry infills has been revealed by several earthquakes and investigated by many authors. Recently, several innovative infill solutions have been proposed to mitigate such interaction, which could result in widespread damage in both the masonry and the RC structure and sometimes jeopardize the building stability and the occupants’ safety. One solution consists in the partitioning of the masonry infill into several sub-panels, relatively sliding along specific joints. This paper investigates the seismic assessment of this technological solution in the framework of performance based earthquake engineering. A two-dimensional five-storey RC seismic-resistant frame is selected as case study and the performance is assessed by comparing the responses of the same structure infilled with different solutions, made of sliding joints or traditional masonry, or in the bare configuration. Incremental Dynamic Analyses (IDA) is used for the probabilistic determination of fragility curves of the structures. Results show the seismic fragility and reliability of the different investigated structures, especially addressing the probabilities of occurrence of damage at different limit states and quantifying the associated expected annual loss.

A new multistrut macromodel for the analysis of the progressive-collapse response of infilled reinforced concrete (RC) frames is presented in this paper. The model consists of three struts: two outer infinitely rigid and resistant struts and one inner fiber-section strut. The inclination of the struts as well as the stress-strain response are modulated by two parameters that are obtained by means of analytical correlations provided in the paper. The latter link the geometric and mechanical properties of an infilled frame to the geometric configuration and mechanical response of the equivalent strut model. This confers the model the capability to adapt to consider different collapse configurations. The analytical correlations are obtained from an experimental data set of pushdown tests, enlarged with data from refined finite-element (FE) simulations. Validation tests are finally carried out comparing the model prediction with results of experimental and FE pushdown tests not considered for the definition of the empirical database. Results show that, because of its flexibility, the model is sufficiently reliable and, at the same time, of simple implementation in FE analysis software to perform progressive-collapse simulations.

Portal-frame reinforced concrete precast industrial facilities built in Italy between 1960 and 1990 have shown high vulnerability during recent seismic events interesting Emilia region. Post-earthquake damage observations have shown that most of collapses interested portal-frame structures arranged with dry beam-to-column friction joints because of the loss of support due to sliding of beams with respect to columns. At the same time severe damage to column base cross-sections was recognized even in the case of portal-frame systems with beam-column connection devices (fixed joints). The paper investigates the dynamic behaviour of portal-frame precast industrial facilities, especially addressing the inelastic displacement demand as function of the generalized mechanical response of beam-to-column joints. Portal-frames are idealized as 2D inelastic single degree of freedom systems. A framework based on a parametric model developed in OpenSees is defined to build inelastic spectra of maximum relative beam-column displacement demands and maximum column top displacement demands. Inelastic displacement demand spectra are defined for four different sites in Italy (Messina, Mirandola, Naples and Turin), characterized by different seismic hazard. Analytical expressions of spectra approximating numerical results are finally derived to be used for rapid displacement capacity/demand assessments of portal-frame industrial buildings with friction joints or fixed joints. The approach can account vertical component of seismic excitation in a simplified way and can be also used to assess the effectiveness of retrofitting interventions.

A new macroelement model is presented in this paper for the simulation of the in-plane (IP) and out-of-plane (OOP) response of infilled frames subjected to seismic actions. The model consists of two diagonal, one horizontal, and one vertical struts. Each strut is represented by two fiber-section beam-column elements. The model is able to capture the arching action of the wall under an OOP load as well as the interaction between the IP and OOP actions. The proposed modeling approach is sufficiently simple and efficient that it can be used for the static or dynamic analysis of an entire structural system. An experimental validation has been carried out. A further numerical study performed with the macroelement model has shown that wall damage due to IP loads can significantly reduce the OOP resistance of the wall, and this influence depends on the slenderness (height/thickness) of the wall. A more slender wall will suffer a more significant loss of OOP resistance.

Steel jacketing of reinforced concrete (RC) columns is a common retrofitting technique used to restore bearing and deformation capacity of buildings presenting structural deficiencies. For practical reasons, steel angles are in several cases arranged leaving a gap with the end beams or slabs. Despite this disconnection, the angles are still able to support a non-negligible portion of load because of the frictional forces developed along the column-angle contact interface. In these cases, the definition of computational numerical and analytical models for the assessment of reinforced cross sections becomes more complex and must be handled with care. The actual load-carrying capacity of the angles is a function of lateral confinement pressure, cohesive strength, and the friction coefficient between the materials. This paper presents first the results of an original experimental campaign on RC column specimens with and without steel jacketing subjected to compressive axial and eccentric tests. Subsequently, a new approach is proposed to define a plane fiber-section model of the reinforced cross section accounting for the frictional action occurring along the column-angle interfaces. An equivalent stress-strain constitutive model for the angles is calibrated and validated through comparison with experimental results. Finally, a simple analytical stress-block procedure to derive continuous and simplified axial force bending moment domains is illustrated as a method for the hand-verification of reinforced cross sections.

Infill-frame interaction constitutes a still open question both in research and in practicing engineering. Computational models used to predict this interaction are, in most cases, addressing the estimation of the response of the infilled frames when subjected to actions parallel to their plane. However, the observation of the post-earthquake damage has demonstrated that infills, weakened by the in-plane actions, may fail out-of-plane increasing the risks associated to the earthquake scenarios. In spite of this, different studies have shown that infills, if properly designed and supported by the frame, exhibit a significant strength and displacement capacity when called to resist to out-of-plane actions, offering the possibility to develop an arching mechanism in their deformed configuration. The prediction of the combined in-plane out-of-plane response prefigures the new goal of the seismic assessment of masonry infilled frames. This paper presents an in-depth literature review of the capacity models developed for the prediction of the out-of-plane response of infilled frames, from the first flexural based computational models to the models implementing the arching action theory in their formulation. A comparison between the results obtainable is provided in order to compare the models reliability against the results of different experimental tests. A final discussion is devoted to the effectiveness the recent integrated in-plane/out-of-plane macromodels used in 3D structural models. A new promising approach, based on the use nonlinear fiber-section elements, is also outlined providing a numerical testing of the capacity of such elements to naturally account for the out-of-plane arching mechanism.

A common way to model infill-frame interaction is the use equivalent strut macromodels. In most cases these are compression only resistant truss elements defined with a multi-linear axial-force / axial-displacement law. The main difficulty in using this approach is to correctly calibrate such a force-displacement curve (slope of ascending and post-peak branches, critical yielding, peak and residual forces) because of the large number of variables (mechanical and elastic properties of materials) and the different possible damage mechanisms activated for the frame-infill system. Another possible way is using fiber-section elements as diagonal struts. In this case the force-displacement law is substituted by a stressstrain curve. In both cases a reliable definition of inelastic response of the strut, based on mechanical approaches, which are valid in general is not easy, as most of models provide rules valid for specific typologies of infills (e.g. weak or strong infills) and frames (e.g. concrete or steel frames). Based on this, the paper proposes the use of fiber-section diagonal struts with a concrete-type stress-strain relationship calibrated using a semi-empirical approach. The Kent-Scott-Park model, depending on four parameters, is used as reference constitutive law for the strut. Experimental data and additional numerical simulations are used to derive semiempirical correlations linking geometrical and mechanical properties of the frame-infill system to the aforementioned parameters governing nonlinear response of the diagonal. Analytical expressions of the best fitting curves are finally provided and suggested as design equation.

This chapter suggests that an extension of the capability of the traditional inplane macro-models to capture the simultaneous in-plane and Out-Of-Plane (OOP) response of infills. A new simplified macro-model for the assessment of both in plane and out-of-plane responses of infilled frames was developed and validated. The possibility to simulate the arching action is achieved by using distributed plasticity fiber-section elements, able to directly account for the coupling between axial load and bending moment. The arching action is explicitly introduced by the use of fiber-section beam-column elements, which can model the coupling between axial-load and bending moment. The model presented is able to predict simultaneously the In-Plane and OOP response explicitly accounting for arching mechanism and two-way action. The OOP tests were carried out by inflating an air bag enclosed by a reaction panel and monitoring the response in terms of force and displacement of the mid-span joint.

The influence of masonry infills on the in-plane behaviour of RC framed structures is a central topic in the seismic evaluation and retrofitting of existing buildings. Many models in the literature use an equivalent strut member in order to represent the infill but, among the parameters influencing the equivalent strut behaviour, the effect of vertical loads acting on the frames is recognized but not quantified. Nevertheless a vertical load causes a non-negligible variation in the in-plane behaviour of infilled frames by influencing the effective volume of the infill. This results in a change in the stiffness and strength of the system. This paper presents an equivalent diagonal pin-jointed strut model taking into account the stiffening effect of vertical loads on the infill in the initial state. The in-plane stiffness of a range of infilled frames was evaluated using a finite element model of the frame-infill system and the cross-section of the strut equivalent to the infill was obtained for different levels of vertical loading by imposing the equivalence between the frame containing the infill and the frame containing the diagonal strut. In this way a law for identifying the equivalent strut width depending on the geometrical and mechanical characteristics of the infilled frame was generalized to consider the influence of vertical loads for use in the practical applications. The strategy presented, limited to the initial stiffness of infilled frames, is preparatory to the definition of complete non-linear cyclic laws for the equivalent strut.

The prediction of the response of infilled frames through the simplified approach of substituting the infill with an equivalent pin-jointed strut is treated. In this framework the results of an experimental study for the mechanical characterization of different types of masonry infills having the aim of estimating strength, Young modulus and Poisson's ratio are presented. Four types of masonry were investigated and subjected to ordinary compressive tests orthogonally to the mortar beds and along the directions of the mortar beds. The experimental campaign confirmed the possibility of using an orthotropic plate model for prediction of the Poisson's ratio and Young modulus along the diagonal direction of infills (these parameters are requested by a model already known in the literature for the identification of struts equivalent to masonry infills). The experimental campaign made it possible to recognise a correlation between the Poisson's ratios and the strengths of masonries investigated along the orthotropic axes and to obtain the diagonal Poisson's ratio without specific experimental tests. Finally, the experimental responses of some infilled frames were used to test the reliability of the model proposed here. © 2013 RILEM.

We investigate the cw laser performance of Tm:LuV O4 crystals pumped with tunable polarized source and report a roughly twofold improvement to their efficiency with 1 W of output power and broad tunability at room temperature.

Prenatal diagnosis of haemoglobin disorders is accepted to be a useful procedure to avoid births of infants with homozygous diseases. Advances in sampling and molecular techniques, such as polymerase chain reaction (PCR) and chorionic villus sampling (CVS), have made earlier and safer first-trimester prenatal diagnosis possible. However, these procedures need previous studies of at-risk couples, which can be very time-consuming when a number of different beta-thalassaemia mutations occur in the region. We describe the possibility of making a first-trimester prenatal diagnosis by cordocentesis and fetal blood analysis at the 12th week of gestation. We found no statistically significant difference (p greater than 0.05) between beta/gamma values in fetuses at the 12th and 18th weeks of gestation. In seven affected fetuses aborted at the 12th week of gestation, the diagnosis was confirmed in all cases by PCR analysis. These findings suggest that early cordocentesis could be an alternative procedure to CVS and PCR analysis.

556 Background: The BIG1–98 and ATAC trials have proven the effectiveness of 5 years letrozole (LET) and anastrozole (ANA), respectively, compared to 5 years tamoxifen (TAM) for the treatment of postmenopausal women with hormone receptor positive (HR+) early stage breast cancer. This analysis uses similar assumptions to those used in the NICE appraisal in the UK, and country specific input data to estimate the cost-effectiveness of LET vs TAM and ANA vs. TAM from the Belgian, Canadian, UK, and US health care perspective (8 analyses). Methods: The same Markov model was used to estimate the incremental cost per quality-adjusted life year (QALY) gained (ICQ) across the 8 analyses in postmenopausal women with HR+ early stage breast cancer. Model events and assumptions were based on the analysis undertaken by the NICE appraisal team in the UK. Probabilities of breast cancer events (contralateral; locoregional; and metastases) were based on the latest early breast cancer (Lancet) overview. Country-specific cost, utility, and adverse event parameter values were informed by relevant population-based studies. LET and ANA effects were informed by published results of the BIG 1–98 and ATAC trials, which were assumed to cease after therapy discontinuation (other than fracture risk that continued for 5 further years). Costs and QALYs were estimated over the remaining lifetime of a cohort of HR+ women aged 60 yrs, discounted at 3.5% annually. Conclusion: Compared to TAM, adjuvant treatment of postmenopausal HR+ women with LET or ANA for 5 years is a cost-effective use of resources in all of the countries included in this analysis. Based on the model assumptions used by the NICE appraisal team in the UK, the mean results indicate that LET is more cost-effective than ANA, though the confidence intervals are wide. [Table: see text] No significant financial relationships to disclose.

557 Background: Due to subsequent poor prognosis, prevention of distant recurrence (DR) is a primary aim of adjuvant hormonal therapy for early breast cancer. Compared to 5 years TAM in hormone receptor positive (HR+) postmenopausal women, DR relative risks are 0.73 (95% CI 0.6 - 0.88) for 5 years letrozole (LET), 0.84 (95% CI 0.7 - 1.0) for 5 years anastrozole (ANA), 0.73 (95% CI 0.59 - 0.9) for 2–3yrs exemestane after 2–3 years (EXE/TAM). This analysis evaluates the incremental cost per distant disease free year gained from a UK NHS perspective of LET, ANA, EXE/TAM versus 5 years TAM using the same health economic model. Methods: A Markov model described pathways through relevant health states over the remaining lifetime of a cohort of HR+ women aged 61 yrs. Probabilities of breast cancer events (contralateral; locoregional; soft tissue, bone, and visceral metastases) adverse events (endometrial cancer, hip and other fractures, cardiovascular disease, thromboembolic events, and arthralgia) were based on the latest early breast cancer overview, published results of the BIG 1–98, ATAC, and IES trials, and UK population-based studies as appropriate. Conservatively, no carry-over effect was assumed for the AIs after therapy discontinuation. Costs (2005 UK£) of breast-cancer care were obtained from a primary costing study in Scotland, and treatment costs for AEs were obtained from published studies. Costs and DR-free years were discounted at 3.5% annually. Results: The mean durations of DDFS were estimated to be 12.81, 12.66, 12.57, and 12.35 years for LET, ANA, TAM/EXE, and TAM, respectively. The incremental cost per distant disease free year gained of LET vs TAM is £10,379 (95% CI £5,286-£17,818), of ANA vs TAM is £11,428 (95% CI £5,071- £48,856), and of TAM/EXE vs TAM alone is £11,020 (95% CI £4,820-£36,947). Conclusion: Compared to 5 years TAM, adjuvant treatment of postmenopausal HR+ women with an AI is a cost-effective use of UK NHS resources. Based on the mean results, LET appears to be the most cost-effective of the three AIs, despite its higher acquisition cost compared to ANA in the UK, though the confidence intervals are wide. [Table: see text]