Combined In-Situ and Laboratory Minor Destructive Testing of Historical Mortars

ABSTRACT

Mortar is of all masonry components the most difficult to be experimentally characterized in heritage buildings. This article investigates the possibility of combining different in-situ and laboratory minor destructive testing (MDT) techniques to assess the strength of mortar in historical brickwork. Lime mortar and clay brick walls were built in the laboratory and then tested in order to derive empirical correlation rules among three different MDT techniques: double punch test (DPT), helix pull-out test (HPT), and pin penetration test (PPT). The outcomes of this activity were used eventually to assess the mortar properties of an important historical heritage structure, Casa Puig i Cadafalch, located near Barcelona. The research is intended to promote the use of MDT in studies and conservation works on built cultural heritage by providing criteria for the evaluation of the strength of existing mortar with respectful sampling and testing techniques.     

A CAPACITY PREDICTION PROCEDURE FOR CONCRETE-FILLED STEEL COLUMNS

A seismic design procedure for partially concrete-filled box-shaped steel columns is presented in this paper. To determine the ultimate state of such columns, concrete and steel segments are modelled using beam-column elements and a pushover analysis procedure is adopted. This is done by means of a new failure criterion based on the average strain of concrete and steel at critical regions. The proposed procedure is applicable to columns having thin- and thick-walled sections, which are longitudinally stiffened or not. An uniaxial constitutive relation recently developed is employed for concrete filled in the thick-walled unstiffened section columns. Modifications are introduced to this model for other types of columns. Subsequently, the strength and ductility predictions obtained using the present and previous procedures are compared with the corresponding experimental results. Comparisons show that the present procedure yields better predictions. It is revealed that the inclusion of the confinement effects and softening behaviour of concrete is important in the present kind of prediction procedures. Furthermore, an extensive parametric study is carried out to examine the effects of procedures and geometrical and material properties on capacity predictions.     

DUCTILITY REDUCTION FACTOR OF MDOF SHEAR-BUILDING STRUCTURES

In this paper, the results of recent studies on inelastic seismic response of MDOF shear-building structures are presented. In the last few decades, the concept of response modification factor R has been introduced and developed to account for inelastic nonlinear behaviour of structures under earthquakes. In this paper, an attempt has been made to adjust and extend this concept through introducing a modifying factor R _T . This factor is used for dynamic analysis of MDOF structures, including the calculation of inelastic response spectra. Sensitivity analysis was carried out to identify the parameters that have influence on R _T . It has been demonstrated that R _T is predominantly a function of number of stories, and accordingly a relationship has been suggested. Finally, an approximate approach has been developed for evaluating the seismic strength and ductility demands of MDOF structures.     

THE USE OF SIMPLE PULSES TO ESTIMATE INELASTIC RESPONSE SPECTRA

Inelastic response spectra are estimated for elasto-plastic SDOF systems subjected to strong earthquake ground motions by applying the strength reduction factors determined for a simple pulse to the elastic response spectrum of the ground motion. This approach relies upon similarities in the strength reduction factors computed for earthquake ground motions and for short duration pulses. The accuracy of the estimated inelastic spectra obtained using 24 simple pulse waveforms is assessed in order to identify subsets of just several pulse waveforms that are suited for this purpose. Based upon the ground motions and pulses investigated, this approach appears to be equally applicable to short and long duration ground motions and those having near-fault forward directivity features.     

Accessing Hunter-Gatherer site structures using Fourier transform infrared spectroscopy: applications at a Taltheilei settlement in the Canadian Sub-Arctic

The results of Fourier transform infrared spectroscopy on soils and caribou bone from a Taltheilei culture settlement in northern Canada contribute to developing micro-archaeological approaches suitable for locating and characterizing hearth and midden features on hunter-gatherer sites. A weak yet pervasive signal for montgomeryite was developed from the diagenesis of dispersed ash and caribou processing residues. Disordered calcite, carbonate hydroxylapatite, charcoal, and burned bone in two pit-house hearth deposits indicate that both wood and bone were used for fuel. Crystallinity indices and carbonate/phosphate ratios for bone indicate high intensity burning. These data, in tandem with the presence of semi-subterranean dwellings, demonstrate that this particular tundra-based encampment was occupied during cold seasons, a type of settlement behaviour previously unrecognized in the Taltheilei archaeological record. Our results confirm that Fourier transform infrared spectroscopy is an accessible, rapid, and cost effective means of discovering micro-archaeological evidence valuable for reconstructing hunter-gatherer site structures.     

Ascetic or affluent? Byzantine diet at the monastic community of St. Stephen’s,Jerusalem from stable carbon and nitrogen isotopes

Stable carbon and nitrogen isotope ratios from bone collagen in skeletons from the Byzantine (5th–7th century AD) monastery of St. Stephen’s in Jerusalem were examined in conjunction with a review of historical sources detailing dietary practices during this period in the Levant. Relatively low δ¹³C ratios (−19.0 ± 0.5‰, 1σ) indicate a diet consisting primarily of C₃ sources and display continuity with textual records describing monastic daily life. Conversely, human δ¹⁵N values (9.6 ± 1.2‰, 1σ) are enriched in ¹⁵N relative to local fauna (7.3 ± 1.1‰, 1σ) and point to the contribution of animal protein to the diet, an unexpected result based on both the rarity and expense of these luxury food items as well as dietary prohibitions associated with an ascetic monastic lifestyle. No sex-based differences in diet were detected for either δ¹³C or δ¹⁵N values, suggesting that men and women consumed isotopically similar foods. As the vast majority of monastic communities in the ancient Near East were located in the desert, the urban setting of St. Stephen’s monastery allows for a unique glimpse into a rarely-explored facet of Byzantine life.     

Transition from hunting to animal husbandry in Southern,Western and Eastern Finland: new dated osteological evidence

The beginning of animal husbandry in Finland is one of the most debated topics in Finnish archaeology. For this study a total of 69 bone materials from archaeological sites in Southern, Western and Eastern Finland, dating from the Middle Neolithic to the Early Metal Period, were analysed: 52 represented identifiable animal bones. These data were complemented with those from previously analysed bone materials. A total of 19 domestic animal bones were radiocarbon-dated to determine their connection with a particular cultural period. However, 13 of them proved to belong to the historical and not the prehistoric period, emphasizing the importance of radiocarbon-dating and context awareness when interpreting prehistoric bone materials. Among the radiocarbon-dated material were the oldest dated sheep, cattle and horse bones in Finland. The oldest radiocarbon-dated domestic animal bone in Finland, from sheep or goat, derives from the Late Stone Age Kiukainen Culture site, while cattle and horse bones date to the Bronze Age. This is later than expected. However, the available material does not exclude the possibility that some animal husbandry was practised in Finland earlier. Nevertheless, domestic animal bones are rare in samples dated to the cultural periods studied, while hunting and fishing represented important subsistence activities.     

Material Characterization and Micro-Modeling of a Historic Brick Masonry Pillar

A masonry pillar composed of solid clay bricks, cement mortar and infill is extracted from a historical structure and tested in concentric compression. It is subjected to cyclic and monotonic loads up to compressive failure.

In parallel, samples are extracted from the pillar and are subjected to destructive tests. Non-destructive tests are performed on the pillar, as well. The properties of the constituent materials are critically examined and their role in the maximum load reached and the failure mode obtained are discussed.

Finally, a finite element micro-model of the pillar is used for the simulation of the pillar test. The influence of the existing damage on the pillar is investigated using the model, resulting in a fair approximation of the global Young’s modulus, maximum load and the failure mode.

Highlights

●?A brick masonry pillar extracted from a historical building is tested in compression.

●?Material samples extracted from the pillar are characterized by mechanical tests.

●?A finite element micro-model of the pillar is used for the simulation of the compressive test.

●?The effect of damage on the compressive strength of the pillar is numerically investigated.     

A Comparative Study on the Compressive Strength of Bricks from Different Historical Periods

The aim of this article is to present the results of compressive strength tests for bricks from different historical periods. The studies were conducted on hand-molded and mechanically formed bricks. The bricks that were used for the studies came from historical structures from the center of the royal city of Crakow. Compressive strength was determined on rectangular prisms and on cylinders cut out from bricks in various directions—anisotropy and shape effects were then analyzed.

?The basic aim of the conducted studies was to estimate the possibility of carrying out the strength tests on relatively small samples and re-calculating these results on normalized brick strength determined according to EN772–1. Based on the tests results, a range of correlation coefficient values for cylinder samples with diameters of 30 mm and 50 mm was given. It was indicated that for the tested historical bricks characterized by significant material non-homogeneity within the element and sensitivity to damages while cutting out the samples, correlation coefficients are higher than for bricks used contemporarily.

?The results of these studies are presented alongside the findings from existing studies on the compressive strength of bricks.     

An Examination of Terminal Archaic Bone and Antler Implements from the Firehouse Site,Dearborn County,Indiana

The Firehouse site (12D563) is a Terminal Archaic Riverton culture site located on a bluff overlooking the confluence of the Ohio and Great Miami Rivers in Dearborn County, Indiana. Excavations at the site in 2003 and 2004 yielded a highly diverse assemblage of around 300 bone and antler implements. Such large assemblages of organic tools are rare outside of wet sites, rockshelters, and shell middens and provide a unique opportunity for the study of tool forms not typically recovered in the Midwest. A typological analysis of the Firehouse assemblage indicates some similarities between these tools and Riverton culture bone and antler implements from the type sites in Illinois. Additionally, a microscopic analysis of manufacturing microtraces indicates that most tools were made using a lithic shaving (rather than an abrasion) technique.