Amjad Naseer

Observed Seismic Behavior of Buildings in Northern Pakistan During the 2005 Kashmir Earthquake

Recent earthquakes in Pakistan demonstrated that the region is highly seismic. Masonry buildings constructed with stones, concrete blocks, and fired-clay bricks and concrete buildings were damaged during the 8 October 2005 Kashmir earthquake. This paper presents the seismic behavior of reinforced concrete and masonry buildings in northern part of the North-West Frontier Province (NWFP) and Kashmir during the earthquake. Most of the buildings were observed to be nonengineered or semi-engineered. The paper presents an overview of the 1937 Quetta building code and the 1986 and 2007 building codes of Pakistan. Lessons learned during the earthquake are also presented.

Seismic Behavior of Unreinforced and Confined Brick Masonry Walls Before and After Ferrocement Overlay Retrofitting

This study presents experimental results of quasi-static load test conducted on two full-scale brick masonry walls, one unreinforced and the other confined, to investigate their in-plane lateral load behavior before and after retrofitting. The walls were constructed closely following the masonry system commonly used in Pakistan and in most South Asian countries. The walls before retrofitting were tested to their peak resistance. The damaged walls were then retrofitted with grout injection followed by ferrocement overlay and retested to their ultimate failure under the identical conditions. The effectiveness of the proposed confinement and retrofitting scheme was assessed from the damage pattern, energy dissipation, and force-deformation behavior of the walls tested before and after retrofitting. The test results before retrofitting show that the capacity of confined masonry wall is almost double to that of unreinforced masonry wall. The test results after retrofitting indicate that the applied retrofitting scheme significantly enhanced the lateral load capacity of the unreinforced masonry wall, however it was marginally beneficial in the confined masonry walls. The test results are also compared with American Society of Civil Engineers (ASCE) standards in terms of stiffness, strength and acceptable deformations. It is concluded that the guidelines provide reasonable estimates of the test observations.

Experimental Seismic Performance Evaluation of Unreinforced Brick Masonry Buildings

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.

Experimental Behavior of Full Scale URM Building Retrofitted with Ferrocement Overlay

This paper presents a study on the behavior of a damaged full scale unreinforced brick masonry building, retrofitted with ferrocement overlay and cement based grout injection, tested under cyclic loading. Damage mechanism and force-deformation behavior of the retrofitted structure are compared with its pre-damaged response to quantify the beneficial effects of retrofitting scheme. The lateral load capacity of the retrofitted building was significantly improved and the damage mechanism was transformed from mixed compression-flexural-shear mode to a more stable flexural rocking mode. The energy dissipation capacity, however, remained unchanged and the deformation capacity was slightly decreased.

Performance of Pakistani volcanic ashes in mortars and concrete

Two Pakistani volcanic ashes, VA1 (as is and calcined) and VA2 (as is), were incorporated into mortar cubes, concrete cylinders, and concrete beams as a partial substitute for ordinary Portland cement (OPC), and were studied in detail. The X-ray diffraction patterns showed that both ashes possessed crystalline as well as amorphous phases. The pozzolanic activity index (PAI) of VA1 at 7 d was below 75%, whereas it was 80% at 28 d. The pozzolonic activity indices in OPC mortars containing VA2 were much higher than those for VA1, both at 7 and 28 d. In mortar cubes and concrete cylinders, approximately the same compressive strengths were observed in samples containing 100% cement as in those incorporating a 10% replacement of cement by either VA1 or VA2. Mortar cubes soaked in 5% sodium sulphate solution demonstrated consistently improved resistances to sulphate attack as ash content increased in the mortar. Similar results were also observed in water absorption tests. Modulus of rupture of all concrete beam...

Seismic Performance Assessment of Non-Compliant SMRF-Reinforced Concrete Frame: Shake-Table Test Study

ABSTRACT Seismic performance assessment is carried out for reinforced concrete structure built in low-strength concrete lacking confining ties in beam-column joint. Shake-table tests were performed on 1/3rd scaled two-story frame using design-spectrum-compatible accelerogram, scaled to various target levels. The frame is observed with beam longitudinal bar slip and pullout. Joints with no confining ties experienced extensive damage, observed with cover/core concrete spalling. The frame could resist 70% of the design ground motion to remain within the code-specified drift limit. The code requirement for minimum column depth will not avoid joint damageability in case of low-strength concrete and joints lacking confining ties.

Shake Table Test of Confined Brick Masonry Building

This paper presents the shake table test of a one-forth scaled model, representing a typical Pakistani three stories confined brick masonry building. The model was constructed following complete model similitude and subjected to a series of sinusoidal base motions of increasing amplitude at a constant frequency equivalent to the predominant frequency of JMA Kobe-1995 earthquake record. The dynamic test data was processed and analyzed to generate the force-deformation curve, ductility ratio and response modification factor of the system. A shear-dominated failure mode was observed. As expected, the ground storey was found to suffer more damage than the other two stories. Out-of-plane failure of walls and crushing of concrete in confining elements were also noted in the final test runs. Based on the damage mechanism and force-deformation characteristics, various performance levels are suggested.

Earthquake Disaster Mitigation through Retrofitting of Unreinforced Concrete Block Masonry Buildings

This paper presents an experimental study on the improvement of unreinforced block masonry buildings against earthquake disasters. Unreinforced concrete block masonry piers have been tested for lateral strength before and after retrofitting. Welded mesh and injection of cement grout techniques have been used for piers retrofitting. The analysis of experimental results demonstrates that proper retrofitting can decrease the risk to concrete block masonry buildings in future scenario earthquakes. Retrofitting increases not only the overall strength of unreinforced masonry piers but also the ductility.

Review of Blast Loading Models, Masonry Response, and Mitigation

Different models for prediction of blast loading, response of masonry structure against blast load, and various mitigation strategies are discussed. Variation of peak positive incident pressure with scale distance in free field spherical burst and surface burst scenarios, proposed by different researchers, is presented and compared. The variation is found significant in the region of small scaled distances. Blast wave parameters in urban environment have been found different from the free field scenario. Effects of geometry, boundary conditions, and material properties on response of masonry buildings were found significant. Different mitigation strategies such as blast wall, landscaping, architecture, and retrofitting techniques are presented.

USE OF RUBBER WASTE IN CONCRETE TO REDUCE ENVIRONMENTAL POLLUTION- AN OVERVIEW

With on growing industrial development, tonnes of solid waste are generated every year. Managing, disposing and recycling of these waste has turned out to be a great challenge in recent times. Typically, waste generated from industrial and domestic activities is dumped in open spaces. However dumping of solid waste in open spaces is hazardous to environment; therefore researchers have explored new means to effectively manage such waste. Tyre wastes have no exception; it cannot be readily recycled or reused. They are dumped in open grounds around the world. In Pakistan they pose a bigger threat as they are burnt, which results in emission of harmful gases in the atmosphere. Therefore, it is necessary to reuse these rubber wastes to reduce environmental pollution. Rubber wastes can be used in concrete as a partial replacement of aggregates resulting in lightweight concrete. Using rubber wastes in concrete enhances the impact resistance, thermal insulation and sound insulation at affordable strength. This paper reviews the viable use of rubber wastes in concrete industry to address the problem of disposal of such wastes.