SEISMIC RESPONSE OF REINFORCED CONCRETE FRAMES INFILLED WITH WEAKLY REINFORCED MASONRY PANELS

The research work presented in this paper is related to the seismic response of RC frames infilled with weak masonry panels, as it is traditional in many seismic prone countries in southern Europe. More specifically, the benefits derived from the insertion of a light reinforcement, in the mortar layers or in the external plaster, are studied in some detail.

Tests have been performed on different types of single bay, single storey, infilled frames to investigate the in-plane response at different earthquake intensity levels and the out-of-plane strength as a function of the in-plane damage. A series of parametric simulations have then been performed, calibrating the models used in the test results, to evaluate the effects of the different panels characteristics on the response of whole buildings, with different infill patterns. Both in-plane and the out-of-plane response have been considered. The results are described in terms of peak ground acceleration required to induce given limit states of serviceability or damage relatively far from the collapse of the structure, which is governed by the RC frame design more than by the infill panels properties.     

Initial evidence of plant and animal-origin organic additives from the second-century bce earthen plaster of rock-cut caves of Karla,India*

Analytical investigations through phytochemical screening, scanning electron microscope (SEM) and light microscopic observation of the earthen plaster of Karla Caves of western India identified the presence of antifungal, antibacterial and insect repellent Careya arborea stem fibres as a vegetal additive. The scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX) study also revealed the inclusion of rice (Oryza sativa) husk as a plant additive in the plaster. In the high rain-fed coastal regions of western India, the antimicrobial, antioxidant and termite-resistance properties of C. arborea helped the survival of the plaster in unfavourable climatic conditions. Besides, the C. arborea and rice husk together played a role in reducing cracks, decreasing the density, and imparting a plasticity and a durability to the plaster. The liquid Fourier-transform infrared spectrometer (FTIR) of organic extracts revealed carboxylic acid (fatty acids)-based additives in the earthen plaster. From the gas chromatography-mass spectrometry (GC-MS) analysis of the plaster, the presence of animal milk fat, animal and vegetable fat, and vegetable oil was identified, and probably used to strengthen the earthen plaster for their resistance to tensile stress. The analysis also diagnoses the inclusion of methyl commate B, a resinous material obtained from the Burseraceae plant family, which has antimicrobial properties, through GC-MS analysis.     

陕西旬邑西头遗址出土彩绘白灰面的成分和工艺分析

对陕西旬邑县西头遗址出土的彩绘白灰面进行了成分和制作工艺分析。采用偏光显微分析、扫描电镜能谱、X射线衍射,拉曼光谱分析了该彩绘面的颜料和石灰层成分,采用气相色谱-质谱联用技术(GC-MS)分析了该彩绘面的胶料成分。结果表明,该彩绘面的颜料由铁红,铁黄和绿土构成。白灰层由碳酸钙构成,部分样品中存在双层白灰层。GC-MS分析表明,该彩绘面的胶料含动物胶,可能还含蛋类。通过比较研究发现,旬邑彩绘白灰面的制作工艺和与后期壁画制作工艺相似,对其组成和工艺的研究将有助于探索先周时期关中地区壁画的起源和发展。     

Uses of Gypsum in Spanish architectural heritage: Typologies and some unique construction techniques

ABSTRACT

In Spain, gypsum and its many typologies play an important role as a construction material in Spanish architectural heritage. Its historical use is mainly a direct consequence of the abundance of gypsum deposits and a constructive tradition which began in ancient times. In addition to being a sign of constructive identity, gypsum is a clear example of the strong link between traditional architecture and the natural resources of the territory. The aim of this article is after to identify gypsum deposits and gypsum architectural heritage found in different parts of Spain and to explain the different gypsum typologies—other than powdered gypsum—used. Finally, the most unique construction techniques are described, differentiating between structural elements, partitions, and enclosures, as well as architectural elements and surface finishes.     

Effect of natural polymers from cissus glauca roxb on the mechanical and durability properties of hydraulic lime mortar

The tradition of using lime as a binder has been in practice over the centuries and is cited in the architectural feats of all kinds of civilizations. Besides the basic ingredients of lime, sand and water, organic admixtures were also mixed into the mortars to modify fresh and hardened state properties as well as to enhance its durability. The motivation of the present study was to develop a replacement of synthetic admixtures by the bio-admixtures. The plant extract of Cissus glauca Roxb (CGR) which is being used in ancient temples and monuments in Kerala has been tested as admixture in varying concentrations and fermentation periods in lime mortar mix. The admixture is polysaccharide rich and a moisturizing agent.

Tests were conducted to measure changes in microstructure of the mortar; fresh state properties such as setting time and workability, mechanical properties such as compressive strength and flexural strength. Also, physical characteristics of admixture modified mortars such as bulk density, porosity and water absorption were also determined. Morphological analysis using SEM with EDX, mineralogical analysis using XRD and organic analysis adopting FT- IR have been done to validate the results of mechanical and physical tests. Capillary water and salt absorption by suction and resistance to salt crystallization cycles were measured as an indicator of durability properties.

The admixture modified mortar resulted in increased mechanical properties and reduced water absorption. It also limits the capillary rise of water and salt intrusion through the hydrophobic nature. The admixture modified mortar have also offered better resistance against the damaging action of deteriorating salts such as sodium chloride and sodium sulphate crystallization cycles. Polysaccharides and proteins in the plant extract interact with the calcium hydroxide of slaked lime and forms complexes. Hence the, natural polymer has increased the durability of hydraulic lime mortars used for repair and it could be a natural alternative to synthetic admixture.