Muhammad Kalimur Rahman
King Fahd University of Petroleum and Minerals
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Featured researches published by Muhammad Kalimur Rahman.
Composites Part B-engineering | 2000
Muhammad Kalimur Rahman; Mohammed H. Baluch; Ali H. Al-Gadhib
Abstract This paper addresses the problem of stress buildup in the repair layer of a concrete patch repair system resulting from moisture diffusion. As moisture evaporates from the repair layer into the surrounding ambience of known relative humidity, the hardened concrete substrate restrains free shrinkage movement of the repair layer. As a consequence, primary tensile stresses are set up in the repair layer together with shear and peeling stresses at the interface of the repair layer-concrete substrate. The repair layer under non-uniformly increasing tensile shrinkage stresses undergoes restrained creep in tension, which results in the development of secondary stresses in the system. The secondary stresses due to restrained creep being of opposite sign to that of restrained shrinkage serve to relieve the primary shrinkage stress field and the net or combined stress buildup as a result is reduced. A finite element based computer program used for computing the time dependent moisture loss profile in the repair system is interfaced with a finite element based 2-D stress analysis program for computing the time dependent restrained shrinkage and creep stresses. Variation of normal and shear stresses across depth and width at critical locations in the patch repair and temporal variation of these stresses are presented. Influence of ultimate free shrinkage strain e sh ∞ and the buildup of tensile stresses versus the evolution of tensile strength capacity f ′ t of the repair is highlighted. Also, possible zones of failure are identified in the repair layer and at the interface of the patch repair system.
Materials | 1999
Muhammad Kalimur Rahman; Mohammed H. Baluch; Ali H. Al-Gadhib
During the repair and rehabilitation of concrete structures, mistakes in design, selection of materials, and construction practices will lead to incompatibility between the repair and the existing concrete substrate. Most of the literature reported in the field of repair reveals that dimensional incompatibility, drying shrinkage in particular, is one of the major problems of concrete repair. This paper addresses the problem of stress buildup in concrete repair in the form of a jacketed column resulting from moisture diffusion. As moisture evaporates from the external jacket into the surrounding ambience of known relative humidity, the hardened concrete column restrains free-shrinkage movement of the repair layer. As a consequence, primary tensile stresses are set up in the jacket caused by restrained shrinkage. The jacketed layer under increasing tensile stresses is also subjected to tensile creep deformation, which results in a stress field of reversed sense as that caused by restrained shrinkage. These secondary stresses caused by restrained creep serve to relieve the primary shrinkage-associated stress field, and, as a result, the net or total stress buildup is reduced. A nonlinear finite element model is used to obtain the time-dependent moisture loss profile in the jacketed column. This model is interfaced with a finite element-based two-dimensional stress analysis program called SHCPAN for computing time-dependent restrained shrinkage and creep stresses. For a typical column repair, numerical experiments are carried out to highlight the influence of both a sealed jacket/column interface and a porous interface on the stress buildup in the jacketed columns.
Journal of Materials in Civil Engineering | 2015
Andrew S. Griffin; Jung J. Kim; Muhammad Kalimur Rahman; Mahmoud Reda Taha
AbstractMotivated by the need to improve oil well integrity for potential carbon capture and storage through CO2 sequestration, nanosilica was hypothesized capable of improving the quality of oil well cement (OWC) in medium and deep oil wells. In this study, OWC was mixed with 1 and 3% nanosilica by weight to produce OWC pastes with water to binder ratio (w/b) of 0.45. The specimens were cured under high temperature and pressure, simulating what occurs in oil wells. A method of analysis combining Si29 nuclear magnetic resonance (NMR) and nanoindentation is proposed. The results are compared with observations extracted from nanoindentation in which classification of hydration products is based on the elastic modulus of the different categories of calcium silicate hydrate (C-S-H). The results show that the degree of hydration, the degree of reactivity, and silicate polymerization increase under the elevated curing condition compared with the ambient condition. It seems that C-S-H generated by the pozzolanic...
Journal of Materials in Civil Engineering | 2014
Walid A. Al-Kutti; Muhammad Kalimur Rahman; Mohammed A. Shazali; Mohammed H. Baluch
AbstractA multiphysics formulation for chloride diffusion in an RC beam with stress-induced damage quantifying the enhancement in chloride diffusivity due to damage is presented. An experimental investigation involving measurement of chloride profile was conducted on RC beams damaged under applied flexural stress. Numerical simulation of the RC beam is carried out using a two-dimensional finite-element approach incorporating the damage due to the applied stress, chloride binding, and the chloride diffusion in the model. Concrete is assumed to be a perfectly elastoplastic (Drucker-Prager) material and the steel as an elastoplastic (von Mises) material with hardening. Drucker-Prager parameters, cohesion c, and friction angle φ are obtained by calibrating numerical load-deflection (P-Δ) curve to an experimentally determined (P-Δ) plot for beams loaded in flexure. Defining a scalar damage index as the degradation in elastic modulus expressed in terms of total strains, the chloride transport problem is address...
information processing and trusted computing | 2016
Mobeen Murtaza; Muhammad Kalimur Rahman; Abdulaziz A. Al-Majed
In oil and gas well cementing a robust cement sheath is required to ensure long-term integrity of the wells. Successful completion of cementing job has become more complex, as drilling is being carried out in highly deviated and high pressurehigh temperature (HPHT) wells. Use of nanomaterials in enhanced oil recovery, drilling fluid, oil well cementing and other applications is being investigated. This paper presents the results of an experimental study conducted to investigate the effect of nanoclay as an additive, on the mechanical and rheological properties of TypeG cement slurry under HPHT conditions. Nanoclay based cement mixes were prepared by replacing cement with 1%, 2% and 3% nanoclay, and admixed with silica flour, and other chemical admixtures. Evolution of compressive strength, thickening time and rheological properties were measured under HPHT conditions. Nanoclay at 1% in cement slurry enhances the compressive strength with accelerated strength development at early ages. The thickening time and plastic viscosity of the nanoclay cement mixes increases significantly as the percentage of Nanoclay increases in the cement slurry.
Archive | 2014
Basheer H. Al-Gohi; Cem Demir; Alper Ilki; Mohammed H. Baluch; Muhammad Kalimur Rahman
In this paper, the seismic vulnerability of unreinforced masonry walls is assessed by conducting a numerical study on the interaction of axial and lateral resistance. The walls are modeled in an ABAQUS environment, using a plastic damage model originally developed by Lubliner et al. (Int J Solids Struct 25(3):299–326, 1989) and further extended by Lee and Fenves (J Eng Mech ASCE 124(8):892–900, 1998). The model yields interesting interactive collapse mechanisms that occur as the axial loading on the wall is increased. The different modes of failure identified as the axial load is increased include (i) rocking mode, (ii) sliding mode, (iii) staggered head/bed joint failure, (iv) diagonal cracks through wall blocks accompanied by staggered head/bed joint cracking, and (v) crushing of wall blocks or bricks.
Archive | 2014
Danish Ahmed; Mohammed H. Baluch; Muhammad Kalimur Rahman; Alper Ilki
This paper presents a finite element simulation to capture the nonlinear response of a typical low strength beam-column joint tested at ITU and also results of the finite element modeling and experimental program conducted at KFUPM for beam-column joints in reinforced concrete construction. Finite element analysis is performed using the software DIANA, simulating the concrete response through Drucker-Prager plasticity with a tension cut-off as failure criterion and using for the reinforcing steel Von-Mises plasticity with multi linear isotropic hardening. The failure mode and deformation response of low strength concrete beam-column joints was predicted with a good correlation between the experimental and finite element results.
SPE Middle East Oil and Gas Show and Conference | 2011
Abdulla Dossary; Abdulaziz A. Al-Majed; Enamul Hossain; Muhammad Kalimur Rahman; Scott S. Jennings; Riyadh Ahmad Bargawi
Cementing is one of the most important and crucial issues in the oil field, especially for high pressure and gas bearing formations. It is difficult to achieve a good zonal isolation in such formation types, where pressure is abnormal and formation fluid contains corrosive fluids and gases. A common problem associated with highly overpressurized zones is cross-flow after cementing. Fluid flow from an over-pressured zone to a low-pressure, highpermeability zone can lead to deterioration of the existing production hardware. Work over operations that attempt to repair cement voids — including: perforation, squeezing and use of casing patches or scab liners — are not recommended, as they do not provide long-lasting results. In one onshore field in Saudi Arabia, there was a problem related to cementing at high pressure zones. Recently, communication between A (abnormally overpressurized zone) and B (low-pressure zone) formations occurred due to long term sea water injection, and has resulted in production interruption in a few wells. This paper addresses the problem through investigating field practices, including: drilling, cementing, and completion. This study also reviews the field reports and cased hole logs. A three-month study was conducted to evaluate the effects of formation-A water on cement, where the cement was exposed to formation-A water under downhole conditions. The tests for permeability, mechanical properties TGA and EDXRF are presented, in addition to discussions of some of the preliminary findings.
Structural Engineering, Mechanics and Computation#R##N#Proceedings of the International Conference on Structural Engineering, Mechanics and Computation 2–4 April 2001, Cape Town, South Africa | 2001
Muhammad Kalimur Rahman
Publisher Summary Durability of a patch repair has become a major concern in the recent times because of cracking and failures of repair layers over a short span of time. A phenomenological model capable of modeling a chain of critical processes that is set off in a patch repair system and results in the generation and dissipation of stresses in the system is developed. Moisture diffusion, a primary critical process in a repair system is addressed in this chapter. A non linear 2D finite element program diffusion analysis (DIANA)-2D is developed for repair systems. A phenomenological approach in which various transport mechanisms at microlevel are lumped together by defining diffusivity of the material at macroscopic level is adopted. A miniature patch repair system consisting of a thin layer of repair material placed over a hardened concrete substrate is analyzed. The spatial and temporal moisture content is obtained, and the moisture loss history over the specified time intervals is computed.
Cement & Concrete Composites | 2013
Jung J. Kim; Muhammad Kalimur Rahman; Abdulaziz A. Al-Majed; Mesfer M. Al-Zahrani; Mahmoud Reda Taha