Implication of rubber- steel bearing nonlinear models on soft storey structures

A.B.M. Saiful Islam,Raja Rizwan Hussain,Mohammed Zamin Jumaat,Kh Mahfuz ud Darain 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.5

Soft storey buildings are characterised by having a storey that has a large amount of open space. This soft storey creates a major weak point during an earthquake. As the soft stories are typically associated with retail spaces and parking garages, they are often on the lower levels of tall building structures. Thus, when these stories collapse, the entire building can also collapse, causing serious structural damage that may render the structure completely unusable. The use of special soft storey is predominant in the tall building structures constructed by several local developers, making the issue important for local building structures. In this study, the effect of the incorporation of an isolator on the seismic behaviour of tall building structures is examined. The structures are subjected to earthquakes typical of the local city, and the isolator is incorporated with the appropriate isolator time period and damping ratio. A FEM-based computational relationship is proposed to increase the storey height so as to incorporate the isolator with the same time period and damping ratio for both a lead rubber bearing (LRB) and high-damping rubber bearing (HDRB). The study demonstrates that the values of the FEM-based structural design parameters are greatly reduced when the isolator is used. It is more beneficial to incorporate a LRB than a HDRB.

Computer aided failure prediction of reinforced concrete beam

A.B.M. Saiful Islam 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.1

Traditionally used analytical approach to predict the fatigue failure of reinforced concrete (RC) structure is generally conservative and has certain limitations. The nonlinear finite element method (FEM) offers less expensive solution for fatigue analysis with sufficient accuracy. However, the conventional implicit dynamic analysis is very expensive for high level computation. Whereas, an explicit dynamic analysis approach offers a computationally operative modelling to predict true responses of a structural element under periodic loading and might be perfectly matched to accomplish long life fatigue computations. Hence, this study simulates the fatigue behaviour of RC beams with finite element (FE) assemblage presenting a simplified explicit dynamic numerical solution to show computer aided fatigue behaviour of RC beam. A commercial FEM package, ABAQUS has been chosen for this complex modelling. The concrete has been modelled as a 8-node solid element providing competent compression hardening and tension stiffening. The steel reinforcements are simulated as two-node truss elements comprising elasto-plastic stress-strain behaviour. All the possible nonlinearities are duly incorporated. Time domain analysis has been adopted through an automatic Newmark-β time incremental technique. The program consists of twelve RC beams to visualize the real behaviour during fatigue process and to obtain the reliability of the study. Both the numerical and experimental results indicate a redistribution of stresses along the time and damage accumulation of beam which severely affect the serviceability and ultimate capacity of RC beam. The output of the FEM analysis demonstrates good match with the experimental consequences which affirm the efficacy of the computer aided model. The controlled fatigue damage evolution at service fatigue load limits makes the FE model an efficient tool in predicting high cycle fatigue behaviour of RC structures.

Incorporation preference for rubber-steel bearing isolation in retrofitting existing multi storied building

A.B.M. Saiful Islam,University of MalayaMohd Zamin Jumaat,Raja Rizwan Hussain,Md. Akter Hosen,Md. Nazmul Huda 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.4

Traditionally, multi-story buildings are designed to provide stiffer structural support to withstand lateral earthquake loading. Introducing flexible elements at the base of a structure and providing sufficient damping is an alternative way to mitigate seismic hazards. These features can be achieved with a device known as an isolator. This paper covers the design of base isolators for multi-story buildings in medium-risk seismicity regions and evaluates the structural responses of such isolators. The well-known tower building for police personnel built in Dhaka, Bangladesh by the Public Works Department (PWD) has been used as a case study to justify the viability of incorporating base isolators. The objective of this research was to establish a simplified model of the building that can be effectively used for dynamic analysis, to evaluate the structural status, and to suggest an alternative option to handle the lateral seismic load. A finite element model was incorporated to understand the structural responses. Rubber-steel bearing (RSB) isolators such as Lead rubber bearing (LRB) and high damping rubber bearing (HDRB) were used in the model to insert an isolator link element in the structural base. The nonlinearities of rubber-steel bearings were considered in detail. Linear static, linear dynamic, and nonlinear dynamic analyses were performed for both fixed-based (FB) and base isolated (BI) buildings considering the earthquake accelerograms, histories, and response spectra of the geological sites. Both the time-domain and frequency-domain approaches were used for dynamic solutions. The results indicated that for existing multi-story buildings, RSB diminishes the muscular amount of structural response compared to conventional non-isolated structures. The device also allows for higher horizontal displacement and greater structural flexibility. The suggested isolation technique is able to mitigate the structural hazard under even strong earthquake vulnerability.

Seismic response variation of multistory base-isolated buildings applying lead rubber bearings

A. B. M. Saiful Islam,Walid A. Al-Kutti 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.5

The possibility of earthquakes in vulnerable regions indicates that efficient technique is required for seismic protection of buildings. During the recent decades, the concept is moving towards the insertion of base isolation on seismic prone buildings. So, investigation of structural behavior is a burning topic for buildings to be isolated in base level by bearing device. This study deals with the incorporation of base isolation system and focuses the changes of structural responses for different types of Lead Rubber Bearing (LRB) isolators. A number of sixteen model buildings have been simulated selecting twelve types of bearing systems as well as conventional fixed-base (FB) scheme. The superstructures of the high-rise buildings are represented by finite element assemblage adopting multi-degree of freedoms. Static and dynamic analyses are carried out for FB and base isolated (BI) buildings. The dynamic analysis in finite element package has been performed by the nonlinear time history analysis (THA) based on the site-specific seismic excitation and compared employing eminent earthquakes. The influence of the model type and the alteration in superstructure behavior of the isolated buildings have been duly assessed. The results of the 3D multistory structures show that the lateral forces, displacement, inertia and story accelerations of the superstructure of the seismic prone buildings are significantly reduced due to bearing insertion. The nonlinear dynamic analysis shows 12 to 40% lessening in base shear when LRB is incorporated leading to substantial allowance of horizontal displacement. It is revealed that the LRB isolators might be potential options to diminish the respective floor accelerations, inertia, displacements and base shear whatever the condition coincides. The isolators with lower force intercept but higher isolation period is found to be better for decreasing base shear, floor acceleration and inertia force leading to reduction of structural and non-structural damage. However, LRB with lower isolator period seems to be more effective in dropping displacement at bearing interface aimed at reducing horizontal shift of building structure.

Potential use of local waste scoria as an aggregate and SWOT analysis for constructing structural lightweight concrete

Islam, A.B.M. Saiful,Walid, Walid,Al-Kutti, A.,Nasir, Muhammad,Kazmi, Zaheer Abbas,Sodangi, Mahmoud Techno-Press 2022 Advances in materials research Vol.11 No.2

This study aims to investigate the influence of scoria aggregate (SA) and silica fume (SF) as a replacement of conventional aggregate and ordinary Portland cement (OPC), respectively. Three types of concrete were prepared namely normal weight concrete (NWC) using limestone aggregate (LSA) and OPC (control specimen), lightweight concrete (LWC) using SA and OPC, and LWC using SA and partial SF (SLWC). The representative workability and compressive strength properties of the developed concrete were evaluated, and the results were correlated with non-destructive ultrasonic pulse velocity and Schmidt hammer tests. The LWC and SLWC yielded compressive strength of around 30 MPa and 33 MPa (i.e., 78-86% of control specimens), respectively. The findings indicate that scoria can be beneficially utilized in the development of structural lightweight concrete. Present renewable sources of aggregate will preserve the natural resources for next generation. The newly produced eco-friendly construction material is intended to break price barriers in all markets and draw attraction of incorporating scoria based light weight construction in Saudi Arabia and GCC countries. Findings of the SWOT analysis indicate that high logistics costs for distributing the aggregates across different regions in Saudi Arabia and clients' resistant to change are among the major obstacles to the commercialized production and utilization of lightweight concrete as green construction material. The findings further revealed that huge scoria deposits in Saudi Arabia, and the potential decrease in density self-weight of structural elements are the major drivers and enablers for promoting the adoption of lightweight concrete as alternative green construction material in the construction sector.

Occurrence, clinical signs, postmortem Lesions and etiology of enterotoxaemia in Black Bengal goats

( K. B. M. Saiful Islam ),( Md. Siddiqur Rahman ),( Md. Ershaduzzaman ),( M. J. F. A. Taimur ),( Hee Jong Song ) 한국가축위생학회 2008 韓國家畜衛生學會誌 Vol.31 No.4

A year round study was carried out to investigate the etiology, clinical signs, postmortem lesions and occurrence of naturally occurring enterotoxaemia in Black Bengal goats. Sixteen goats of different age and sex died in different seasons with sigh associated with entero-toxaemia made the materials of this study. Accidental access to large amount of concentrate was noted as one of the predisposing factors although few cases were reported to occur without known diet change. Younger animals(50%) and males(62.50%) were found more prone to the disease and it was likely to be more prevalent during winter(50%) followed by at rainy season(31.25%) and summer(18.75%). Diarrhoea(81.25%), dullness(56.25%), drooping of the ears(50%), anorexia(43.75%) were recorded as major clinical signs whereas enterocolitis(100%), lung edema(87.50%), fluid filled intestines(87.50%), enlarged mesenteric lymph nodes(56.52%) etc. were most common post mortem lesions found. A few cases showed lesions on heart(31.25%), brain(25%) and/or liver/spleen(18.75%) but no lesion was found on kidney. Thus the so called ``pulpy kidney`` lesion was absent. Intestinal contents were subjected to conventional bacteriological culture based methods to identify the causal agents. Based on the morphological, cultural and biochemical properties the causal agent was identified as Clostridium perfringens. Despite the study was carried out at certain area it showed a clear picture of goat enterotoxaemia in terms of etiology, clinical signs, postmortem lesions and occurrence of goat enterotoxaemia in Bangladesh.

Ready mixed concrete behavior of granulated blast furnace slag contained cement

M. Razaul Karim,A. B. M. Saiful Islam,Faisal I. Chowdhury,Sarder Kashif Ur Rehman,Md. Rabiul Islam 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.2

Due to enhanced construction requirement, ready mixed concrete are being popular day by day. The current study aimed to develop ready mixed concrete using GBFS contained cement and determine its properties of fresh and hardened states. A real scale experiment was set up in a ready mixed plant for measuring workability and compressive strength. The workability was tested after mixing (within 5 minutes), 30, 60, 90, 120 and 150 minutes of the running of bulk carrier. The ready mixed carrier employed spinning motion i.e., rotating around its axis with 20 RPM and running on road with 1km/h speed. The mixing ratio of cement: sand:gravel, water to cement ratio, super plasticizer were, 1:1.73:2.47, 0.40 and 6% of cement, respectively. The chemical composition of raw material was determined using XRF and the properties of cements were measured according to ASTM standards. The experimental results confirm that the cement with composition of 6.89% of GBFS, 4% of Gypsum and 89.11% of clinker showed the good compressive strength and workability of concrete after 150 minutes of the spinning motion in bulk carrier.

Dynamic characteristics and fatigue damage prediction of FRP strengthened marine riser

Islam, A.B.M. Saiful Techno-Press 2018 Ocean systems engineering Vol.8 No.1

Due to the escalation in hydrocarbon consumption, the offshore industry is now looking for advanced technology to be employed for deep sea exploration. Riser system is an integral part of floating structure used for such oil and gas extraction from deep water offering a system of drill twines and production tubing to spread the exploration well towards the ocean bed. Thus, the marine risers need to be precisely employed. The incorporation of the strengthening material, fiber reinforced polymer (FRP) for deep and ultra-deep water riser has drawn extensive curiosity in offshore engineering as it might offer potential weight savings and improved durability. The design for FRP strengthening involves the local design for critical loads along with the global analysis under all possible nonlinearities and imposed loadings such as platform motion, gravity, buoyancy, wave force, hydrostatic pressure, current etc. for computing and evaluating critical situations. Finite element package, ABAQUS/AQUA is the competent tool to analyze the static and dynamic responses under the offshore hydrodynamic loads. The necessities in design and operating conditions are studied. The study includes describing the methodology, procedure of analysis and the local design of composite riser. The responses and fatigue damage characteristics of the risers are explored for the effects of FRP strengthening. A detail assessment on the technical expansion of strengthening riser has been outlined comprising the inquiry on its behavior. The enquiry exemplifies the strengthening of riser as very potential idea and suitable in marine structures to explore oil and gas in deep sea.

Occurrence, clinical signs, postmortem lesions and etiology of enterotoxaemia in Black Bengal goats

Islam, K.B.M. Saiful,Rahman, Md. Siddiqur,Ershaduzzaman, Md.,Taimur, M.J.F.A.,Song, Hee-Jong The Korean Society of Veterinary Service 2008 韓國家畜衛生學會誌 Vol.31 No.4

A year round study was carried out to investigate the etiology, clinical signs, postmortem lesions and occurrence of naturally occurring enterotoxaemia in Black Bengal goats. Sixteen goats of different age and sex died in different seasons with sigh associated with enterotoxaemia made the materials of this study. Accidental access to large amount of concentrate was noted as one of the predisposing factors although few cases were reported to occur without known diet change. Younger animals(50%) and males(62.50%) were found more prone to the disease and it was likely to be more prevalent during winter(50%) followed by at rainy season(31.25%) and summer(18.75%). Diarrhoea(81.25%), dullness(56.25%), drooping of the ears(50%), anorexia(43.75%) were recorded as major clinical signs whereas enterocolitis(100%), lung edema(87.50%), fluid filled intestines(87.50%), enlarged mesenteric lymph nodes(56.52%) etc. were most common post mortem lesions found. A few cases showed lesions on heart(31.25%), brain(25%) and/or liver/spleen(18.75%) but no lesion was found on kidney. Thus the so called 'pulpy kidney' lesion was absent. Intestinal contents were subjected to conventional bacteriological culture based methods to identify the causal agents. Based on the morphological, cultural and biochemical properties the causal agent was identified as Clostridium perfringens. Despite the study was carried out at certain area it showed a clear picture of goat enterotoxaemia in terms of etiology, clinical signs, postmortem lesions and occurrence of goat enterotoxaemia in Bangladesh.

Weight minimum design of concrete beam strengthened with glass fiber reinforced polymer bar using genetic algorithm

Md. Moshiur Rahman,Mohd Zamin Jumaat,A. B. M. Saiful Islam 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.2

This paper presents a generalized formulation for optimizing the design of concrete beam reinforced with glass fiber reinforced polymer bar. The optimization method is formulated to find the design variables leading to the minimum weight of concrete beam with constraints imposed based on ACI code provisions. A simple genetic algorithm is utilized to solve the optimization task. The weights of concrete and glass fiber reinforced polymer bar are included in the formulation of the objective function. The ultimate limit states and the serviceability limit states are included in formulation of constraints. The results of illustrated example demonstrate the efficiency of the proposed method to reduce the weight of beam as well as to satisfy the above requirement. The application of the optimization based on the most economical design concept have led to significant savings in the amount of the component materials to be used in comparison to classical design solutions.