Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650°C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.

Brick masonry is widely used for building construction throughout the world. However, unreinforced brick masonry buildings performed poorly in the 2005 Kashmir earthquake, in Pakistan, resulting in a decline in the use of brick masonry. In order to investigate and quantify the performance of brick masonry against the seismic forces by confining it through typical stiffer, line elements (column and beams), a full-scaled room model of an area 3048 × 3658 mm (10 × 12 ft) and height of 3353 mm (11 ft) was constructed using confined brick masonry. The model was tested under quasistatic loading system. Crack pattern was noted at the end of each loading cycle. The response of the model was interpreted through a hysteresis curve, which was then idealized by a bilinear curve. A comparison of the results has been made with four different studies done on the similar model made of unreinforced brick masonry before and after retrofitting and unreinforced concrete block masonry before and after retrofitting previously tested at the same testing facility.

This paper presents an experimental study on the performance of a full-scale unreinforced brick masonry (URM) building system tested under quasi-static loading at the Earthquake Engineering Centre, University of Engineering and Technology in Peshawar, Pakistan. The configuration and materials used in the single-story URM building are typical of those found in the northern areas of Pakistan affected by the 2005 Kashmir earthquake. This study is a part of ongoing research for the earthquake impact assessment of the city of Abbottabad. Combined shear and flexural behavior was observed during the test. The experimental data was analyzed and is presented in the form of force-deformation hysteresis loops and envelope curves. Based on the measured data, different performance levels have been established. The measured response of the test structure is also compared to the estimated response obtained using three capacity evaluation procedures and the two are found to be in good agreement.

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The pozzolanic potential, mechanical strength, and stress-strain behavior of a locally available wheat straw ash (WSA) as a partial substitute of cement was evaluated in this study. Various samples of a locally available wheat straw were burnt to ashes at three distinct temperatures and characterized through X-ray powder diffraction and energy dispersive X-ray spectroscopy. The WSA obtained from burning at 550 °C was found highly amorphous and possessed suitable chemical composition to be used as pozzolanic material. The burned WSA was grounded to achieve the desired fineness and mortar cubes and concrete cylinders were cast by substituting 15%, 20%, 25%, and 30% cement with it. The strength of mortar and concrete decreased with increasing amounts of WSA except for those containing 15% WSA, where it slightly increased than the respective control samples at later ages, i.e., 28 and 91 days. Despite reduced strength at high replacements (20%, 25%, and 30%), the strength activity index values met ASTM C618 requirements for pozzolanic materials. Moreover, the compressive strength of concrete containing 20% WSA exceeded to that of control concrete at 91 days. The stress-strain relation of concrete containing 15% to 20% WSA also showed comparable stiffness and toughness to those of control samples at all ages. Particularly, the concrete containing 15% WSA showed significant improvement of strength, stiffness, toughness, and ductility at 91 days. Lastly, the results of mechanical strengths and pozzolanic reactivity were successfully validated indirectly by measuring the porosity of mortars and thermo-gravimetric analysis of cement pastes, respectively. Based on current findings and their validation, WSA can be used as a substitute of cement up to 20% in the production of sustainable normal strength concrete for their application in common domestic building projects.

Infilled walls are considered as nonstructural elements in reinforced concrete (RC) frame buildings. However, they can interact with the bounding frame when subjected to lateral load and can change the load resisting mechanism and failure pattern. This paper presents the results of two full scale (single storey and single bay) RC frames which were tested using quasi-static loading. Of these, one was a bare frame whereas the second frame was constructed with infilled brick masonry wall. The data of hysteresis curves, strength, capacity curve, stiffness, energy dissipation, displacement ductility, overstrength factor, response modification factor and performance levels have been presented and discussed. The test results highlighted the positive influence of infilled wall on stiffness, strength, energy dissipation and ductility of RC frame. It was also observed that response modification factor is sensitive to the frame geometric configuration.