Testing low strength concrete of collapsed frame buildings

Within the scope of measurement of in-situ material properties, the paper presents results of two studies carried out by the Authors for forensic investigations of concrete properties in existing reinforced concrete frame structures collapsed during the 2009 Aquila earthquake. The two edifices were built in the 1960s; the results provide data on low-strength material property measurement. Cores were extracted: 53 specimens in two series for the first building and 16 in the second. Compression tests were carried out following EN12390-3, providing data on density, compression strength and ultrasound velocity. Non-Destructive Testing with SONREB measurements were also carried out in the first building. The test results are analyzed and discussed in relation to the design documents and the Italian code specifications at the time of the design of the building. The conclusions show that the concrete quality was very poor in relation to low quality construction practices

The structural life of a Cathedral and the worksites of the Duomo di Milano

The life of Milan Cathedral is described with the evolution of the structural system and the restorations carried out throughout the centuries. The organization of the Veneranda Fabbrica del Duomo di Milano is outlined, with the latest restoration interventions. The case study of the construction and restorations of the Tiburio with its supporting pillars is analyzed, from the initial design to the dramatic damage in the 20th century. The rebirth of the Cathedral was the fruit of restorations preserving the structural identity of the monument up to the present. The conclusions address the study of damage and maintenance and repair operations of mon-umental heritage buildings within a life cycle perspective, in relation to the underlying socie-tal values

[Biblioteca universale : in continovanza delle voci, principianti per C. nella quale alfabeticamente sono descritti I Cavalieri d'ogni ordine ... : alcuna de'gia pubblicati in due volumi dall' accuratissimo abbate Giustinian : bensi ora accresciuti di numerose importanti notizie, figure in rame, e copiosi indici

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Tit. y autor tomado de portadillaTit. en antep.: "Ordines equestres"Antep. y portadillaLas h. de lám. grab. calc. representan ordenes de caballería, religiosas, heráldica, escudos de armas, medallones, etc. y algunas están firmadas por: "Ant. Luciani auct. scul. Venet.

A state of the art of flat-slab frame tests for gravity and lateral loading

The research was carried out in preparation of the SlabSTRESS experimental campaign, that is a part of the Transnational Access activities of the SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe) project.This paper presents a critical review of the state of the art of experimental research concerning the seismic response of reinforced concrete flat slab frames. After a summary of tests on connections, the paper examines tests carried out on frames with gravity and cyclic lateral loading, and shake table tests; scaled specimens and one real scale study are included. A discussion of the results reached so far is provided focusing on the global response, the different load types and effects; the ultimate rotations at failure in relation to the gravity shear and a classification of different failure modes for different types of connections. Based on this analysis, the research needs are highlighted. An experimental program launched to address these open questions is described. Further open topics are highlighted.authorsversionpublishe

Dose estimation in clinical phase - contrast mammography with synchrotron radiation

Naslov doktorske disertacije: Procena doze u fazno – kontrastnoj kliničkoj mamografiji sa sinhrotronskim zračenjem Cilj. Sinhrotronsko zračenje odlikuju karakteristike koje ga čine posebno interesantnim za primenu u mamografiji. Njegov širok energetski spektar i visok fluks omogućavaju selekciju monohromatskog snopa izuzetno visokog intenziteta; energija prilagođena svakoj pojedinačnoj pretrazi uspostavlja bolju ravnotežu u odnos između predate doze i kvaliteta proizvedenog snimka. Zahvaljujući laminarnoj formi snopa, smanjen je doprinos rasejanog zračenja, što se odražava na dodatnu redukciju doze. Odlična prostorna koherencija izvora omogućava primenu novih fazno senzitivnih metoda (fazno kontrastni (eng. phase – contrast, u daljnjem tekstu PhC) i difrakcioni imidžing) i akviziciju snimaka detalja koje odlikuju loše apsorpcione karakteristike. Ove imidžing tehnike omogućavaju prevazilaženje osnovnog nedostatka konvencionalne mamografije - zavisnost kontrasta slike od razlika apsorpcionih karakteristika strukturnih komponenti dojke; ovo je posebno evidentno u mamografiji detalja relativno velikih dimenzija, čije apsorpcione karakteristike su veoma bliskih istim od tkiva dojke koje ga okružuje (eng. low contrast masses). Istraživanja predstavljena u ovom doktorskom radu fokusirana su na dve međusobno povezane grupe ciljeva: Procenu radijacionog rizika prouzrokovanog izlaganjem x – zračenju tokom PhC sinhrotronske mamografije Valutaciju efikasnosti PhC sinhrotronske mamografije (u smislu dozimetrijskih parametara) u odnosu na konvencionalnu mamografsku metodu. Metode. Mamografska pretraga izvođena je simultarnim skeniranje dojke pacijenta i detektora kroz monohromatski sinhrotronski snop laminarne forme. Optimizovana ekspozicija podrazumevala je podešavanje parametara pretrage (energije snopa i brzine skeniranja) u skladu sa morfološkim karakteristikama (gustina žlezdanog tkiva) i debljinom organa. Ista se odvijala u dve faze, prva («preskeniranje») koja je imala za cilj definiciju parametara pretrage i druga u kojoj se vršila akvizicija snimka («skeniranje»). Procena srednje glandularne doze (MGD) tokom mamografske pretrage pacijenata bazirala se na primeni koeficijenata normalizovane glandularne doze za mamografiju sa nekonvencionalnim snopom zračenja, koji uspostavljaju odnos između izmerene kerma vrednosti na površini kože pacijenta (ESAK) i MGD. Ovi koeficijenti uzimaju u obzir individualne osobine dojke pacijenta (debljina i sastav) i kvalitet x-zračenja. Za tu svrhu korišćen je sistem za dozimetriju s dve jonizacione komore, dizajniran specijalno za monitoring snopa laminarne forme, koji garantuje maksimalnu osetljivost u energetskom intervalu predviđenom za mamografsku pretragu s sinhrotronskim zračenjem (15 – 22 keV). Za eksperimentalnu proveru matematičkog algoritma za procenu srednje glandularne doze, realizovanu sa LiF TLD dozimetarima (GR – 200) i mamografskim fantomima (eng. Mammography Phototimer Consistency Testing Slabs - MPCTS), kao parametar valutacije analitičke metode korišćena je relativna procentualna razlika između procenjene («analitičke») i izmerene (TLD) doze. Još jedna eksperimentalna provera analitičke metode realizovana je sa različitim mamografskim fantomima (CD - Contrast Detail Mammography Phantom i "Rachel" - The Anthropomorphic Breast Phantom) kao i uzorcima tkiva dojke dobijenim nakon parcijalne i totalne mastektomije. U ovoj valutaciji, «analitičke» doze su upoređene sa odgovarajućim vrednostima istih izračunatih primenom koeficijenata normalizovane glandularne doze za mamografiju sa nekonvencionalnim snopom zračenja. Rezultati. Uzimajući u obzir analizirani uzorak od 88 mamografske pretrage, srednje vrednosti kerme na površini kože pacijenta iznosile su 0,38 ± 0,34 mGy i 2,19 ± 0,75 mGy, tokom faze preekspozicije i faze akvizicije snimka, respektivno. Iako rezultati pokazuju njen blagi rast sa debljinom, ovaj trend je mnogo umereniji u odnosu na isti u konvencionalnoj mamografiji; uzimajući u obzir njenu standardnu devijaciju, kerma na površini kože pacijenta tokom akvizicije sinhrotronskog mamografa može se smatrati skoro konstantnom. Procena srednje glandularne doze u PhC sinhrotronskoj mamografiji pacijenata urađena je za standardnu dojku glandularne gustine 50 % («standardna» doza) i za procenjenu glandularnost dojke; obe procene se odnose na izmerenu debljinu komprimovanog organa i sabiraju dozne doprinose iz dveju faza mamografske pretrage. Uzimajući u obzir ukupan analizirani uzorak, njena srednja vrednost je iznosila 0,86 ± 0,26 mGy za standardnu dojku, odnosno 0,82 ± 0,26 mGy za procenjenu glandularnost dojke. Eksperimentalna provera analitičke metode za procenu MGD u sinhrotronskoj mamografiji ukazala je na niže vrednosti ovako izračunatih doza u odnosu na odgovarajuće vrednosti dobijene primenom koeficijenata normalizovane glandularne doze za mamografiju sa nekonvencionalnim snopom zračenja. Simulacijom sinhrotronske mamografske pretrage dojke (glandularna gustina i debljina od 100 % i 4,5 cm, respektivno), potvrđeno je izuzetno slaganje dozne procene dobijene primenom koeficijenate normalizovane glandularne doze za mamografiju sa nekonvencionalnim snopom zračenja i analitičke procene («analitične» doze) urađene s atenuacionim koeficijentima za fotoefekat (prosečno odstupanje doznih procena ovih metoda iznosilo je 4 %); ovo ukazuje da se u sinhrotronskoj mamografiji dozni doprinos rasejanih fotona ne može zanemariv. Odstupanja analitičke procene za ukupan atenuacioni koeficijent od doza dobijenih primenom koeficijenata normalizovane glandularne doze za mamografiju sa nekonvencionalnim snopom zračenja (od 26 do 36 % za energetski interval od 16 do 22 keV) iskorišćeno je za aproksimativnu korekciju «analitičkih» doza na prisustvo rasejanih fotona. Ova korekcija primenjena na analitičke procene za ukupni atenuacioni koeficijent dobijene u eksperimenta sa mamografskim fantomima, pokazala je da merna nesigurnost ove dozne procene (od 7 do 23 %) ostaje u okviru intervala definisanog evropskim standardima za konvencionalnu mamografiju. Zaključak . Na osnovu komparativne analize doza i dozimetrijskih parametara iz konvencionalnih i sinhrotronskih mamografija zaključuje se da: - Sinhrotronskom metodom se ostvaruje «ušteda» kerme na površini kože pacijenta; njena srednja vrednost u konvencionalnoj mamografiji veća je od iste u sinhrotronskoj mamografiji za čak 151 %. - Zahvaljujući monohromatskoj prirodi snopa, u sinhrotronskoj pretrazi uspostavljen je kompromis između kvaliteta snimka i predate doze; za razliku od distribucije «standardnih» doza u konvencionalnoj mamografiji, koja pokazuje rastući trend sa debljinom dojke, ista u sinhrotronskoj mamografiji praktično je konstantna sa ovim parametrom. Prosečna ušteda u MGD tokom mamografskih pretraga sa sinhrotronskim zračenjem procenjuje se na 34 % i 32 %, za standardnu i procenjenu glandularnost dojke, respektivno. Ovo, zajedno sa PhC efektom, razlog je što se za niže primenjene doze sinhrotronskom metodom proizvode snimci boljeg kvaliteta u odnosu na konvencionalnu mamografiju. Interpretacija podataka eksperimentalne provere analitičke metode za procenu doze u sinhrotronskoj mamografiji dala je ohrabrujuće rezultate. Dalji rad na njenom poboljšanju, koji bi imao za cilj smanjenje merne nesigurnosti, mogao bi se orijentisati na više novoa: - Razumevanje naglašene razlike u procenjenim dozama koje su dobijene za ukupni i atenuacioni koeficijent za fotoefekat, s posebnim akcentom na iste u niskoenergetskom području, gde je doprinos Compton – ovog rasejanja zanemarljiv i - Preciznu procenu atenuacionih koeficijenata strukturnih komponenti tkiva dojke, zbog njihovog fundamentalnog značaja za dozimetriju.Title: Dose estimation in clinical phase - contrast mammography with synchrotron radiation Aim. The unique properties of synchrotron radiation (SR) make it a particularly interesting for mammography. Its wide energy spectrum and high photon flux allow selection of highly intense monochromatic beam; the use of the optimal energy for the considered examination establishes a better balance in the relationship between delivered radiation dose and image quality. Thanks to the laminar geometry of the beam, the contribution of scattered radiation is reduced, which brings an additional radiation dose reduction. The high degree of coherence of the source allows the application of phase sensitive methods (Phase Contrast (PhC) and Diffraction Enhanced Imaging), which give a futher improvement on the visibility of very low contrast details. These imaging techniques overcame the major limitation of conventional mammography – image contrast dependance on differences in the absorption properties of structural components of the breast; this is particulary relevant in mammography of relatively large objects having an x-ray absorption coefficient very close to normal breast tissue (low contrast masses). The researches presented in this doctoral dissertation focus on two interrelated sets of objectives: The assessment of radiation risk caused by x-ray exposure during PhC synchrotron mammography Validation of the effectiveness of a PhC synchrotron mammography (in terms of dosimetric parameters) compared to conventional mammography. Materials and methods. The PhC SR mammograhy was performed by simultaneouly scanning the patient's breast and detector through the monochromatic laminar beam. Optimized exposure entailed exam parameters (beam energy and scan velocity) setting on the base of the breast glandularity and thickness. It took place in two phases: the first phase («pre-exposure») which was aimed at the examination parameters definition and the seconde phase («scan») in which the image acquisition was carried out. The estimate of mean glandular dose (MGD) was based on use of the normalized glandular dose coefficients for unconventional x-ray spectra in mammography, which establish a relationship between the Entrance Surface Air Kerma (ESAK) and MGD. These coefficients take into account the individual characteristics of the patient's breast (thickness and composition) and quality of xray beam. For this purpose, an ad-hoc dosimeter system was constructed, consisting of two ionization chambers, designed specifically for monitoring of laminar shaped beam, guaranteeing maximum sensitivity in the energy range specified for mammography with synchrotron radiation (15-22 keV). The experimental verification of the mathematical algorithm for the mean glandular dose calculation, realized with LiF TLD dosimeters (GR - 200) and mammography phantoms (Mammography Phototimer Consistency Testing Slabs - MPCTS), uses the relative percentage difference between the estimated («analytical») and measured (TLD) dose as the validation parameter. Another experimental verification of the analytical method was performed with several mammography phantoms (CD - Contrast Detail Mammography Phantom and "Rachel" Anthropomorphic Breast Phantom) and breast tissue samples, obtained after partial and total mastectomy. In these experiments, «analytical» doses were compared with the corresponding values calculated using the normalized glandular dose coefficients for unconventional x-ray spectra in mammography. Results . Taking into account the analyzed sample of 88 mammographyc examinations, the mean ESAK value was 0.38 ± 0.34 mGy and 2.19 ± 0.75 mGy, during pre - exposure and image acquisition phase, respectively. Although it increases slightly with a breast thickness, this trend is much more moderate compared to the same in clinical practice with conventional unit; taking into account its standard deviation, the ESAK in SR PhC mammography can be considered almost constant. The evaluation of the patient mean glandular dose in SR PhC mammography has been performed for a standard breast composition, i.e. 50% adipose tissue and 50% glandular tissue by mass («standard» dose), and a estimated breast composition; both doses were calculated for the thickness of the compressed breast and take into account dose contributions from the two phases of SR PhC mammographic examination. Taking into account the total analyzed sample, the mean MGD value was 0.86 ± 0.26 mGy for the standard breast composition and 0.82 ± 0.26 mGy for the estimated breast composition. The experimental verification of the analytical method for the mean glandular dose estimation shows a lower values of thus calculated doses compared to the corresponding values determined using the normalized glandular dose coefficients for unconventional x-ray spectra in mammography. Simulation of SR PhC mammography exam with a 4,5 cm thick, 100 % glandular, breast confirmed very good consistency between a doses determined using the normalized glandular dose coefficients for unconventional x-ray spectra in mammography and «analytical» doses calculated with photoelectric attenuation coefficient (average deviation between doses estimated by these two methods was 4 %); this implies that the dose contribution by scattered photon in SR PhC mammography can not be neglected. Deviation between «analytical» doses calculated with total attenuation coefficient and doses determined using the normalized glandular dose coefficients for unconventional x-ray spectra in mammography (from 26 to 36 %, in the energy ragne from 16 to 22 keV) was used for correction of «analytical» doses by the presence of scattered photons. This correction, applied to «analytical» doses (calculated with total attenuation coefficient) delevered in experiments with mammography phantoms, showed that the dose measurement uncertainty (7 to 23 %) remains within range defined by the European guidelines for conventional mammography. Conclusions . In conclusion, the comparative analysis of dose values and dose parameters in conventional mammographic examination and SR PhC mammography show that: - The PhC synchrotron based method leads to the ESAK saving; average ESAK value in conventional mammography is even 151 % higher than in SR PhC mammography - Due to the possibility of selecting the most suitable beam energy, in the SR - based mammography, a compromise has been established between image quality and delivered dose; unlike the conventional mammography, in which the «standard» dose distribution shows an increasing trend with the breast thickness, in the SR PhC mammography it is nearly constant with the same parameters. The average dose saving in mammography with SR is 34% and 32 %, for standard and estimated breast composition, respectively. The PhC SR mammography method reveals a prominent increase in image quality with respect to conventional mammograms even at lower delivered dose. The interpretation of experimental results, obtained from measurements on verification of the analytical method for the dose assessment in SR mammography, gave encouraging results. A further work on its improvement, aimed to reduce measurement uncertainty, could be oriented toward: - A better understanding of differences in the estimated doses obtained for total and photoelectric attenuation coefficient, with a special emphasis on low energy region, where the contribution of Compton - scattering is negligible, and - Accurately verification of the attenuation coefficients of breast tissues, because of their fundamental importance for mammography dosimetry

Effigies, et series chronologica ministrorum generalium: totius ordinis S. Francisci minorum conventualium concinnatae

16 portraits of the Minister Generals of the Order of Friars Minor, each with handwritten descriptive text and preceded by a portrait of St. Francis of Assisihttps://digital.sandiego.edu/aafh-mss/1000/thumbnail.jp

Bond Strength of Highly Corroded Reinforcement and Cover Delamination

A recent experimental and analytical research program (Zandi et al., 2011-a, b) provided bond strength values for highly corroded bars. The test program included both main reinforcement and stirrup corrosion. These results must be compared to the rather wide but scattered database of test results in this field. Two relevant sources for comparison are the indications of FIB MC2010, based on the existing literature, and some recently published test results (Regan and Kennedy Reid, 2009). The latter simulated the delamination of the concrete cover by casting the concrete either flush to the bar surface or at mid-barrel i.e. the bars had either no cover or even were partly external to the concrete; the reinforcement was not corroded. The paper summarizes the tests by the authors and develops the comparison with the other studies. The conclusions discuss the choice of bond strength values for the assessment of existing structures and future research outlooks

Bond Strength of Highly Corroded Reinforcement and Cover Delamination

A recent experimental and analytical research program (Zandi et al., 2011-a, b) provided bond strength values for highly corroded bars. The test program included both main reinforcement and stirrup corrosion. These results must be compared to the rather wide but scattered database of test results in this field. Two relevant sources for comparison are the indications of FIB MC2010, based on the existing literature, and some recently published test results (Regan and Kennedy Reid, 2009). The latter simulated the delamination of the concrete cover by casting the concrete either flush to the bar surface or at mid-barrel i.e. the bars had either no cover or even were partly external to the concrete; the reinforcement was not corroded. The paper summarizes the tests by the authors and develops the comparison with the other studies. The conclusions discuss the choice of bond strength values for the assessment of existing structures and future research outlooks

Severely Corroded Reinforced Concrete with Cover Cracking: Part 2. Anchorage Capacity

There is a growing need for reliable methods of assessing the load-carrying capacity and remaining service life of corroded structures. In an ongoing research by the authors, issues that have not been investigated in the methods and models available today to calculate the remaining load-carrying capacity of the corroded structures are identified. Two main issues; i.e. high amount of corrosion leading to cover spalling and the effect of corroding stirrups, were investigated in an experimental program. Pull-out tests were carried out on beam-end specimens with long embedment length to study the anchorage capacity of a corroded bar. The specimens were subjected to electrochemical corrosion process leading to different corrosion penetrations prior to mechanical loading. Details concerning electrochemical corrosion setup, corrosion-induced cracking and numerical modelling of a corroding bar are presented in a companion paper subtitled “Part 1. Crack initiation, crack propagation and cover delimitation”. Three types of specimens, with stirrups, without stirrups and with corroding stirrups, were subjected to pull-out test. The test results showed a significant influence of stirrups not only on corrosion-induced cracking but also on anchorage capacity and failure mode in the pull-out test. Finally, the corrosion and mechanical testing phases were simulated in a finite element model using the corrosion and bond models earlier developed by Lundgren [1,2]. The outcomes of the numerical modelling help to further understand the effect of high corrosion penetrations and presence of stirrups on failure modes observed in the experiments