Asian Journal of Civil Engineering

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Article
The point movement is defined by six components (3 translational and 3 rotational). In earthquake ground motion, the transitional components are effortlessly measurable by a motion recording device, while the rotational components are not straightforwardly available. It has been a long time since ground motion records are recognized to have six-components; be that as it may, this truth is ordinarily ignored within the seismic design and seismic assessment of the structures. In this study, a 60-story steel structure (High-rise building) with bracing core, outrigger and belt truss system in different heights of the structure is subjected to three-component and six-component nonlinear time history analysis from far fault ground motions, near fault ground motions with forwarding directivity and near fault ground motions with fling step. This study shows that six-component analysis can increase the responses of the structure in comparison with three-component analysis. The effect of rotational components on the responses is negligible more in near fault ground motions in comparison with far fault ground motions (except drift and acceleration). Furthermore, the effect of the rotational components on the drift ratio index is more in comparison with near fault ground motions and with fling step (approximately 15% increase)
 
Article
Concrete is one of the popular construction materials in the world. Performance and durability are the main factors that contribute to its demand. However, long-term issues of weakening and corrosion. In this study, three samples of rectangular beam size of 400 mm × 1200 mm × 6000 mm are checked in terms of wave velocity, elementary, chemical and radio spectrum. Apparently, one of the beams inspected is detected with poor quality from ultrasonic pulse velocity. In addition, the defects are supported by crack evaluation and abnormalities in the samples using radio spectrum. Further check on the concrete quality is done using X-ray fluorescent techniques and carbonation reading. As a conclusion, the outcome of this findings will help to determine any structure failure and factors contributing to the problem. Finally, the relation between wave and radar analysis can identified and solved the structure elements.
 
Article
Self-compacting concrete is highly advanced concrete with much higher fluidity without segregation, bleeding and it is suitable for placing in structures with congested reinforcement of structure like Vierendeel truss under its self-weight without vibration. Mix proportion of self-compacting concrete must ensure a good balance between deformability and stability. Behavior of concrete can be affected by the characteristics of selected ingredients in concrete and the mix proportions. It becomes necessary to evolve a procedure for mix design of SCC. The paper presents an experimental procedure for the mix design of self-compacting concrete for grade M60 and implementation of the same mix at cast in situ heavily dense reinforcement structure-Vierendeel truss of Sitabuldi Metro Station in Nagpur Metro Project. The test results for acceptance characteristics of M60 grade self-compacting concrete such as slump flow, V-funnel, L-box, compressive strength at the ages of 7, 28, and 56 days determined, and results are included here. Successful production of temperature control self-compacting concrete from batching plant, transportation and placement procedures and proper planning of handling and execution of self-compacting concrete at site are presented in this article.
 
Shape and geometry of a simply supported beam-column and its cross section: case 1
Article
Identification of damage to structures in order to prevent its expansion or improvement is an important issue that has received much attention from researchers. In this experimental study, a triangular model was used to apply the embedded cracks with using CNC on the laboratory beam-columns. The size of the elements is such that the effective length of the crack is located inside the element and from it has not been removed. To identify embedded cracks, static data index was used for Euler-Bernoulli beam-columns under axial load. In this laboratory study, two simple beams models with single, multiple damage and different loading scenarios were used. In the first step, the laboratory horizontal displacements are recorded and then included in the index. Finally comparison of laboratory and the numerical results have shown the performance accuracy of the static data base index.
 
Article
Your article is protected by copyright and all rights are held exclusively by Springer Nature Switzerland AG. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com". Abstract Unreinforced masonry structure (URM) consists of a major portion of existing structures in underdeveloped and developing countries all over the world. Most of these URM structures are non-engineered which usually do not conform to local building codes and would be considered significantly deficient to international standards. So, seismic vulnerability assessment of these URM structures is of major significance. The present paper addresses this issue with a systematic approach to assess and analyze the structural vulnerability of a non-engineered URM building. Consequently, a complete retrofitting design procedure is discussed followed by construction and field implementation. Initially, a detailed engineering assessment of the whole structure was carried out which included site investigation, rigorous laboratory and in-situ tests, and development of a 3D finite element model for structural analysis. Analysis showed that lateral shear stresses of the load-bearing walls were higher than their acceptable limits when subjected to code specified loading. The flexural strengths of the RC beams were also found to be inadequate. As a solution, the beams were retrofitted with U shaped reinforced concrete jackets, while two alternative methods were proposed for the retrofitting of the load-bearing walls based on design requirement viz. Ferro-cement overlay (for low stress) and Reinforced Concrete jacketing (for high stress). Stresses under most of the wall strip footings were found to surpass the soil bearing capacity, so retrofitting was done by increasing footing widths to meet the soil's allowable bearing capacity. Finally, the implementation of the retrofitting design in the actual structure along with the construction procedure has been presented. The present study is expected to provide a comprehensive guideline for engineers to carry out seismic vulnerability assessment, structural retrofitting design, and the procedure of its implementation during field construction in the concerned URM structure.
 
Article
Aftershock seismic hazard analysis depends on both mainshock magnitude and elapsed time after the main earthquake. Aftershocks can result in an increment in the seismic demand of the structures. The objective of the current study is to determine a final aftershock spectrum as an applicable outcome in seismic design and assessment of buildings. As a numerical example, aftershock probabilistic hazard analysis (APSHA) was calculated at a location in southern California. The proposed method was applied for four different periods. Furthermore, a three-story existing concrete building was selected and analyzed regarding aftershock spectrum. It was shown that the amount of spectrum follows an upward trend by increasing the amount of main shock magnitude. The second finding was that the spectral value decreases with growth in elapsed time after the mainshock. While both beams and columns did not have enough strength, by applying aftershock to the building, 20% of the columns were required to be retrofitted again, and the figure for strengthened column experienced a rise of about 38%. However, the number of retrofitted beams did not change considerably.
 
Article
Aftershock seismic hazard analysis depends on both mainshock magnitude and elapsed time after the main earthquake. Aftershocks can result in an increment in the seismic demand of the structures. The objective of the current study is to determine a final aftershock spectrum as an applicable outcome in seismic design and assessment of buildings. As a numerical example, aftershock probabilistic hazard analysis (APSHA) was calculated at a location in southern California. The proposed method was applied for four different periods. Furthermore, a three-story existing concrete building was selected and analyzed regarding the aftershock spectrum. It was shown that the amount of spectrum follows an upward trend by increasing the amount of mainshock magnitude. The second finding was that the spectral value decreases with growth in elapsed time after the mainshock. While both beams and columns did not have enough strength, by applying aftershock to the building, 20% of the columns were required to be retrofitted again, and the figure for strengthened column experienced a rise of about 38%. However, the number of retrofitted beams did not change considerably
 
Daily tonnage of MSW generated based on the data of LAs
Article
Aims/ Objectives: This study examines the current municipal solid waste (MSW) management in Sarawak and recommends measures for its improvement. Study Design: This study adopts a qualitative approach involving targeted in-depth interviews guided by a questionnaire. Place and Duration of Study: The study was conducted among 18 local authorities (LAs) in the Sarawak state of Malaysia between January 2019 to June 2019. Methodology: This study is a qualitative survey conducted among 18 LAs in Sarawak, namely Kuching, Limbang, Marudi, Bau, Lundu, Betong, Dalat and Mukah, Kapit, Lubok Antu, Matu and Daro, Maradong and Julau, Serian, Sri Aman, Simunjan, Miri, Saratok, Subis and Lawas. Staff members in the public health section of the LAs were interviewed via phone calls and face-to-face mode. This represents a sampling size of approximately 64% which is deemed sufficient to provide an adequate picture of the MSW management practice in Sarawak. Results: Smaller and remote LAs have lower MSW collection coverage than larger and more developed LAs. MSW is collected generally from 2 times a week to daily using compactors or trucks equipped with bin-lifters. Bins smaller than 240L are usually emptied manually. Waste collection is zoned in each LA and contracted to qualified contractors. Collected MSW is sent to dumpsites or landfills. Currently there are one level-4, two level-3 and three level-2 landfills in Sarawak. Organic waste particularly food residues form the bulk of MSW received at landfills. Waste segregation and recycling is not as widely practiced in Sarawak as the Peninsular Malaysia.Conclusion: The study shows that MSW management in Sarawak is equipped with the basic infrastructure but faces challenges in coverage due to the large area of the state. To improve MSW management, the recommendations comprise continuous road network development, decentralized administration of MSW management, composting, creation of ’recycling ecosystem’, education as well as research and development, backed by the state and federal governments’ commitment and funding.
 
Article
An approach to deal with changing requirements of construction projects is to develop a design that will have the ability to undergo various changes easily. Projects must be designed not only to meet client requirements, but also to meet requirements of construction, operation and throughout their entire project lifecycle. Hence, this paper introduces a modeling method that seeks to incorporate the changeability in designs of construction projects. The proposed method builds on Axiomatic Design approach to eliminate unnecessary changes due to requirements conflicts and to detect necessary changes throughout the project lifecycle. The results of this study indicate that changeability can be incorporated in the early stages of the project by analyzing relationships between functional requirements and design parameters. Changeability can be achieved when any change in functional requirement can be satisfied by a change in the design parameter independently or sequentially. Two construction projects-underground metro and hotel building are used as a case study to elaborate on how the method can be applied.
 
Article
Old masonry walls, which present a limited bending capacity, generally need strengthening in order to provide an overall seismic resistance to old buildings. To achieve such purpose an innovative strengthening technique was developed, consisting in the application of an exterior render layer with a structural role. The flexural resistance improvement of such technique results from the mechanical properties of the materials used and requires a proper application procedure. This innovative solution, henceforth designated as “CFRP reinforced render”, consists of a lime base mortar reinforced with a carbon mesh, applied on one or both faces of the masonry wall. The reinforced render solution, developed within this study, aims to provide improved mechanical capabilities to the strengthened masonry walls while respecting the main principles for rehabilitation of ancient buildings. In particular, it complies with material authenticity/compatibility principle, because it is based on a lime base mortar, and with the structural compatibility principle, as it involves a distributed strengthening all over the main original structural elements—the masonry walls, instead of imposing unbalanced concentrated strength. In this context, an extensive experimental campaign was developed involving in-plane and out-of-plane full-scale bending tests on plain and on strengthened wall specimens reproducing the mechanical and geometrical characteristics of old masonry walls. Based on the experimental results obtained, a numerical approach was developed to simulate the behaviour of the plain and of the strengthened masonry walls for different geometrical configurations and for different mechanical parameters. Besides allowing a better understanding of the behaviour of the strengthening technique, the developed models presented in this paper may aid the design of CFRP reinforced render solutions.
 
Article
Various methods have been proposed in the last decade to determine the maximum credible earthquake for seismic structural design purposes. Uniform risk and uniform hazard approaches are the two ways to investigate the earthquake design spectral acceleration. The current study aims to draw a comparison between uniform risk spectra (URS) and uniform hazard spectra (UHS) at four locations with different soil types in Mazandaran (north of Iran). Since seismic hazard curves were not available for the region of interest, probabilistic seismic hazard analysis was performed at four stations by considering three attenuation relationships to account for local, regional and global effects of earthquakes. The UHS was determined at each station for the 2500-year return period. Furthermore, URS, which leads to one percent probability of collapse of a building in 50 years, was investigated by an iterative technique. It was found that a UHS leads to a greater ground shaking than URS at short periods at all soil conditions. The differences were more evident for a period range of about 0.3–0.4 s and for very strong and soft soil. To sum up, as ASCE 7–10 recommends, using uniform risk spectral acceleration is more confidential for designing short structures on all ground types. The current findings add to a growing body of literature on determination of maximum credible earthquake in seismic design of structures.
 
Chemical composition of r-UFFA, r-UFS, and NFA (test results, % by mass)
Physical properties of r-UFFA, r-UFS, and NFA
Article
The various environmental ill effects from manufacturing of cement have provoked research into the advancement of concrete using a 100% replacement material by activated alkali solutions. Geopolymer concrete is an eco-friendly binder, which has attained significant attention among the researchers worldwide in past few decades. Large quantity of industrial waste ash is generated by thermal power plant, mining industry, timber industry, rice milling industry, steel and iron industry, etc. which have posed the industries a great threat when it comes to the disposal of these waste ash due to the various ill effects on health, environment, scarcity of lands, and other challenging issues. The best way in overcoming these waste management problems can be reduced by implementing geopolymer technology. The fundamental parameter in deciding the potential adoption of eco-friendly concrete in the construction sector is the durability of the construction material. This present study evaluates the influence of reactive silica/alumina present in the normal fly ash, ultra-fine fly ash, and ultra-fine slag, and blends of ultra-fine fly ash and ultra-fine slag on the strength development and durability properties. Test results indicate that the geopolymer concrete (GPC) exhibited high compressive strength and better durability characteristics when ultra-fine fly ash and slag are blended in optimum ratios to obtain a certain reactive silica/alumina ratio.
 
Article
This paper aims to present the three-dimensional nonlinear seismic response of concrete gravity dams considering contact elements at dam-reservoir interaction interface. Damreservoir contact interface is modeled with three-dimensional surface-to-surface contact elements based on the Coulomb’s friction. A numerical investigation of the effect of hydrodynamic interaction and sliding of the water along the dam-reservoir interface is performed. The maximum horizontal displacements and principal stresses in the different sections of the dam are presented as well as seismic behavior of dam is examined in empty and full reservoir cases. Besides, the damage placements in the concrete dam are evaluated
 
Article
: In the case of an uncontrolled demolition or a terrorist attack no prior knowledge is usually available as to what the exact explosives is and what the exact charge weight is. As well, in most cases the authorities have no idea what the target is to be in advance of an attack. For a designer to design a structure to minimize the damage in such cases is somewhat difficult if not impossible but, nevertheless, it must be done. Once the explosive, either as an IED (improvised explosive device) or VIED (vehicle improvised explosive device), has detonated the normal aftermath of such events such as fragmentation, primary and secondary fires, ground cratering and building collapse are all obvious. From a designers’ point of view, the starting point is to understand in detail all building collapse mechanisms to be able to design for such events and so allow time, if possible, for all those caught inside a building to escape and for structural damage to be minimized. To obtain such design parameters the designer must refer to past uncontrolled demolitions on Australian soil or in countries close by to gauge the most likely threat. Prior to design commencing one also must have clear criteria and strategy in mind to be able to complete a suitable design to ensure his obligation to allow time for people to escape from its collapse is met and damage is minimized. Designers not only have to address new building designs to withstand blast and ballistic loadings but also how to retrofit existing buildings cost effectively against such blast and ballistic loadings. Detailed lists of required criteria and strategies that are necessary so at to arrive at a suitable design for any blast or ballistic loadings likely to being applied to a structure are provided within the paper based on all aspects of an uncontrolled demolition (explosion) that may confront a designer. Keywords: IED, VIED, explosive, fragmentation, building collapse, collapse mechanisms
 
Article
A study was performed to assess the effects of magnetic water with different percentages of natural zeolite (NZ) on self-compacting concrete (SCC) mixes. Over the past decades, a limited number of studies were conducted by researches on the effects of magnetic water on SCC mixes. In addition, it seems that pozzolanic materials such as NZ can affect performance of magnetic water in SCC mixes. Following this, the present study was aimed to survey engineering properties of self-compacting concrete (SCC) containing magnetic water and NZ. To achieve this goal, slump flow, T50, V-funnel, L-box and visual stability index (VSI) were employed to evaluate the rheological properties of concrete mixes. Furthermore, hardened properties were investigated by means of compressive strength, splitting tensile strength, modulus of elasticity and water absorption tests. The concrete test results demonstrated that 20% NZ inclusion and magnetic water in SCC with the water–binder (W/B) ratio of 0.37 led to an optimum mix design and also this mixture could contribute to an increase in compressive strength, splitting tensile strength and modulus of elasticity up to 25%, 8% and 9%, respectively.
 
Article
A study was performed to assess the effects of magnetic water with different percentages of natural zeolite (NZ) on self-compacting concrete (SCC) mixes. Over the past decades, a limited number of studies were conducted by researches on the effects of magnetic water on SCC mixes. In addition, it seems that pozzolanic materials such as NZ can affect performance of magnetic water in SCC mixes. Following this, the present study was aimed to survey engineering properties of self-compacting concrete (SCC) containing magnetic water and NZ. To achieve this goal, slump flow, T50, V-funnel, L-box and visual stability index (VSI) were employed to evaluate the rheological properties of concrete mixes. Furthermore, hardened properties were investigated by means of compressive strength, splitting tensile strength, modulus of elasticity and water absorption tests. The concrete test results demonstrated that 20% NZ inclusion and magnetic water in SCC with the water–binder (W/B) ratio of 0.37 led to an optimum mix design and also this mixture could contribute to an increase in compressive strength, splitting tensile strength and modulus of elasticity up to 25%, 8% and 9%, respectively.
 
Article
In this paper, we compare the seismic provisions of building codes from Nepal, India, Japan, and EU. A brief history of the development of Nepal National Building Code (NBC), Indian Standard Code (ISC), Building Standard Law of Japan (BSLJ), and Eurocode-8 (EC8) is presented. The main steps and considerations to calculate the fundamental natural period and base shear are highlighted. Thereafter, we computed the fundamental natural period and base shear of a prototype building from the high seismic region following the code provisions of NBC, ISC, BSLJ, and EC8. The sum of computations and reviews contend that NBC, ISC, and EC8 depict close results than the Japanese building code.
 
Article
When a high explosive charge detonates in the proximity of an above ground structure, blast waves impact the structure over time and cause different levels of damage and possible collapse of the structure depending on the type of explosive detonated and the size of the charge weight used. Such an event occurs when a building is subjected to an uncontrolled demolition (terrorist attack) resulting from the actions of an improvised explosive device (IED). For a structural engineer to design in advance for such an event that must be anticipated at the start of the design process both for the type of explosive and the charge weight that may be used is demanding. Any blast will see three pressures impact the structure and these are incident pressure (so P), reflected pressure (гα P) and dynamic pressure (q s). The latter is the smallest of the three whilst the remaining two produce the largest pressures. Examples exist worldwide as to the outcome of buildings not being designed to carry blast loadings which has inevitably resulted in the destruction of the structure and the death or injury to those unfortunate enough to be caught inside the building as it collapsed. Structural designers design for many loadings such as dead loads, live loads, wind loads, and earthquake loads but the application of blast loads is not the norm and so only carried out in exceptional cases and at great cost.
 
Article
Designers who design structures to mitigate against blast loadings have another duty and that is to design for the effects of fragmentation not only caused from bulk explosives but also impact from projectiles. Impact causes damage to a structure and inevitably results in debris from penetration and perforation (breach) of the structural elements. This debris is in fact the result of the damage outcome to a structure either from the blast loading or projectile impact. Fragmentation is the result of the blast waves impacting the structural elements resulting in scabbing and spall both of which manifest themselves in the production of fragmentation. This fragmentation is propelled outwards at velocity causing supplementary damage to the structure, adjoining structures and individuals caught near the fragmentation. Those designing for fragmentation must consider many parameters from the geometry of the impacted structural element, to the velocity of the fragments, the weight of the fragments and the range of the fragments. As has been said the fragments cause damage and the designers' overall duty is to design to mitigate against damage and death or injury to individuals. The pool of worldwide knowledge on this topic is growing exponentially particularly as the need arises with weapons of high velocity and sophisticated projectiles of extreme lethality and range.
 
Causes of construction delays identified from literatures
-Ranking of group causes based on frequency by different respondents
-Ranking of group causes based on severity by different respondents
-Kruskal-Wallis test for top ten causes of delay
Article
Schedule delay in building construction projects is considered as one of the main reasons for project failure in developing countries. Likewise, privately funded building construction projects in Bangladesh have been suffering due to schedule delays. This study investigated the main causes of delay in privately funded large building projects in Bangladesh. To determine the causes of delay, a structured interview with 70 respondents was conducted with project owners, consultants, and contractors. Using the importance index analysis method, the study identified the critical causes of delays. The 10 most important causes are: (1) lack of experienced construction managers; (2) lowest bidder selection; (3) owners’ fund shortage; (4) lack of proper management by the owners; (5) improper planning and scheduling; (6) lack of skilled workers; (7) inaccurate time and cost estimation by the contractors; (8) site constraints; (9) improper progress monitoring and cost control; and (10) contractors’ cash flow problem during construction. Furthermore, Kruskal-Wallis test indicates that there is no significant variation among the three groups of respondents, i.e. owners, consultants, and contractors. The finding of this study is significant for identifying the most important causes of delay in large building projects. It also identifies the responsibility of major stakeholders (i.e. owners, consultants, and contractors) in causing a schedule delay, which helps them to find mitigation measures for the potential delays of upcoming projects in advance. Although this study provides the insight into the causes of delay in privately funded large building projects in Bangladesh, it is also significant for other similar developing countries.
 
Article
The local buckling has always been known as an undesirable and destructive phenomenon in steel structures. Thus, it is necessary to identify the effective factors in local buckling of the steel box column. Currently, box columns are generally fabricated by welding plates using fillet or groove welds with various manufacturing patterns,in terms of weld leg size and the overlap length of the plates. Hence, the evaluation of these patterns and also the control of local buckling in built sections seem to be essential. In this research, a variety of columns with different welding patterns, including groove and fillet welds with various overlap values and weld legs are numerically modeled and their local buckling behavior is studied in the finite element domain by using ABAQUS software. A suitable welding pattern is proposed by assessing the energy absorption, as well as stress distribution, stress concentration and finally local buckling in steel box section columns. The obtained results indicate that, the sections fabricated utilizing groove welds, have the best nonlinear performance. And also a suitable implementation of fillet welds to fabricate steel box columns is to consider 20% overlap length and 80% weld leg size to plate thickness as this model subject to small amount of local buckling. This model has shown less than 6% reduction in plastic capacity and energy absorption in comparison with groove welding. Another method is to use 50% for both overlap length and weld leg size to plate thickness. This model has shown less than 8% reduction in plastic capacity and energy absorption in comparison with groove welding. In addition, unsuitable implementation of fillet welds especially with small overlaps and weld leg sizes has shown a 12.5% reduction in plastic capacity and energy absorption, compared to groove welding (PDF) Numerical investigation of fillet welds effects on the ultimate strength and local buckling of box steel columns.
 
Model configuration
Comparison between FE results and experimental data
(a,b) Procedure of stud transforming into spring (c) FE model of the stud and its surrounding concrete (d)Verification of FE model e) load-slip curve defined as input data for non-linear spring 
Load-deflection curves of girders repaired with 5 layers of FRP
Ultimate load carrying capacity versus depth of the notch 
Article
There are limited studies available regarding the repair of steel beams and steel-concrete composite girders using fibre-reinforced polymer (FRP) reinforcements. However, among these studies there are a few resources dealing with numerical modelling of such beams using the finite element (FE) method. In this research a finite element simulation was developed to evaluate efficiency of various types of FRP plates, externally bonded on tension flange, on the enhancement of flexural strength of damaged composite girders. The primary defect in girders was simulated by inserting a notch through the tension flange and partial in web at mid-span. The occurrences of initiation and propagation of debonding as well as the effect of partial shear connection between the steel beam and concrete slab were taken into account. To ensure the validity of the proposed numerical model, the obtained results from the current analysis were compared with those existing experimental studies. This study focused on varying types of FRP and the amount of damage. Four common FRP types varying in modulus elasticity were employed to evaluate their influences on flexural strength and stress concentration at the critical region, i.e. the root of the notch. It was observed that higher modulus FRPs have more capability to limit the high principle strain in the critical region and, consequently, to reduce the rate of crack propagation across the steel section. Finally, the interaction between the FRP thicknesses and the notch depths in the web of steel beam was examined.
 
Article
When subjected to an earthquake motion, a structure should absorb and dissipate lots of energy in different ways, allowing the structural members to enter the inelastic range enabling them to absorb the energy by their deformations. As structural members enter the inelastic range, permanent deformations occur, and to continue utilization of structure, those members which are too deformed or cannot be utilized anymore should be strengthened or replaced with new members, an operation which is difficult and costly. Therefore, the dampers installed in the structure, through energy absorption induced by earthquake, prevent other parts of the structure to enter inelastic range; as a result, following an earthquake, different parts of the structure can be either still utilized or fixed and replaced, if necessary, by checking the dampers. According to the aforementioned things, this study aims to examine the structures to which damper is added as a retrofitting method. For this purpose, by selecting a number of intermediate steel moment frames, seismic vulnerability of these frames in the near- and far-field earthquakes was examined and such parameters as damage to frames and stories, relative story displacement, base shear and roof displacement were examined. In this study, viscoelastic dampers are used in order to reduce drift and structural damage. The results after dampers installation in the middle span of frames were compared with/without using damper, then it was concluded that viscoelastic dampers play an important role in absorbing energy and reducing damage in buildings. Moreover, drift and base shear as well as roof displacement decrease to a great extent. Comparing near- and far-field earthquakes, it was observed that the intensity of near-field earthquakes was higher causing devastating effects in buildings; installation of dampers, however, highly reduces these damages. Furthermore, the effect of dampers on taller buildings was found to be more, and greater reduction was seen in the examined parameters.
 
(b): Sectional properties of 40m height monopole tower
(b): Sectional properties of self-supporting tower of height 30m
(b): Sectional properties of self-supporting tower of height 50m
a): Geometrical configuration with member notation of self-supporting tower of height 50m for all considered basic wind speeds
Article
Monopole and Self-Supporting Towers are the most common types of Telecommunication Towers adopted in construction industry. This paper presents a comparison between Monopole and Self-Support type Towers with different heights of 30m, 40m and 50m for basic wind speeds of 33m/sec, 47m/sec and 55m/sec. Dead loads and Wind loads are considered for analysis of the tower using STAAD(X) Tower software which is tailor made for analyzing Telecommunication Towers. It is concluded from this study that Self-Support Towers have lower lateral displacements compared to the Monopole Towers of same height for same amount of loading. This is because they have higher stiffness. But, the steel quantity required for Self-Support Towers is about 2 times more than the Monopole Towers for a given tower height, wind speed and loading. However, due to their rigidity, Self-Support Towers have more load carrying capacity than Monopoles. For towers of height below or equal to 40m, Monopoles might be preferred. But, with the increase in height beyond 50m, Self-Support Towers are recommended. This is because, in case of any unexpected and abnormally high wind speeds during cyclones, the structural rigidity will be intact and the damage and repair for the structure may not be so high unlike Monopole.
 
Article
This paper deals with the efficiency of a hybrid vibration control for rigid buildings structures under earthquakes. The hybrid control consists of a base isolator and tuned mass damper (TMD) or active tuned mass damper (ATMD). The active control force is calculated within a feedback loop by the mean of the linear quadratic controller (LQR) designed to penalize the displacement and the velocity of the floor on which the ATMD is installed. A total of four cases are studied based on the placement and the type of the control system either passive TMD or active TMD. The lower and top floor alternatively carries the TMD control system. The case of a rigid six-degree of freedom base isolated frame structure illustrates the effectiveness of the hybrid control through simulations. Simulation results, obtained from real time-history data of three earthquakes (El Centro, Northridge and Loma Prieta) show that the proposed control is effective. The hybrid control system is able to reduce the vibration amplitudes especially the base isolator displacement and acceleration without affecting the super-structure response regardless of the placement of the TMD control system. Such a hybrid control system can protect high importance buildings containing sensitive equipment.
 
Article
This paper studies the increase in strength and stiffness of the composite double-layer grids, whose top-layers combine the steel frame elements with concrete decks. Firstly, the paper obtains the ultimate load capacities of square concrete decks with and without ribbed edges under various support and load conditions. Then, the load capacity of a composite double- layer grid is obtained under various loads, geometric and support conditions. A comparison of the results indicates that: the composite grid exhibits 2 to 5 times higher load capacity than the corresponding non-composite grid. In addition, a composite grid with (roller +pin) supports has about 20% of the load capacity of the identical grid with (pin +pin) supports.
 
Details of the domain used in numerical study. 
Streamline for N plan shape tall building at 0° and 90° wind angle
Article
The principal aim of this case study includes the determining of wind pressure co-efficient and wind velocity analysis of N-plan shape tall building using k-e method. The wind angles varying from 0° to 180° at 30° interval scale of 1:300 and terrain category 2. A square plan with same area compared with the N-shape model also validated with different codes AS/NZS: 1170.2 (2002), ASCE/SEI 7-10 (2010), BS: 6399-2 (1997), EN: 1991-1-4 (2005) and IS 875 (part 3) (1987). The wind velocity and force coefficients around this model at different faces are also discussed here.
 
Article
In recent years, it has been observed that historical unreinforced masonry buildings are the most damaged structures after an earthquake event, mainly due to the degradation of materials and the non symmetric distribution of bearing walls. Its conservation is then important when it represent an architectural artistic asset especially when it is still functional. In this paper, the seismic performance-based assessment developed within the European PERPETUATE project was applied adopting two different modeling strategies, structural element model SEM for macroelements with regular geometric forms and continuum constitutive law model CCLM for arcades. The case of this study is an historical masonry building, considered as a valuable architectural heritage of Mostaganem city in Algeria. The assessment is performed by static non linear analysis of the building assuming that the response of the structure is well described by a set of macroelements that are analyzed separately. Pushover analysis of each bearing wall was implemented using Tremuri software for SEM model and the finite element Ansys software for CCLM model by supposing a micro-modeling of materials. The results obtained by combination of the aforementioned models allowed us to establish fragility curves that represent the response of the whole asset corresponding to four performances levels.
 
Article
In this research, a new numerical method is presented to evaluate the linear and especially the nonlinear dynamic response of single degree of freedom systems. This technique is based on the simultaneous usage of energy and force equilibrium equations which is called the Modified Energy Method. At first, a simple linear system is selected to illustrate the method in detail with harmonic and earthquake loading. Furthermore, several different nonlinear examples are studied such as: a-Coulomb Friction (nonlinear damping) b-Duffing Oscillator (material nonlinearity) and c-Large-angle Simple Pendulum (geometric nonlinearity). The results of the proposed method are compared with other methods, and it was found that this method is more accurate compared with the 4th order Runge-Kutta method for nonlinear analyses.
 
Article
Non-linear static and dynamic analyses are performed on a set of reinforced-concrete frame buildings to derive static and dynamic capacity curves. The static capacity curve is ‘transformed’ using the displacement modification method for comparison with dynamic capacity curve. It is observed that the static procedure predicts the collapse capacity in close agreement with the dynamic procedure, after adjusting for the effect of spectral shape. The obtained static and dynamic capacity curve parameters along with associated uncertainties are used to obtain the collapse fragility curves. Collapse probabilities obtained both from static and dynamic procedures, are observed to be in close agreement.
 
Article
Corrosion of reinforcement bars, large base shear due to earthquake load and tensile defect of concrete are the most important failure factors in an RC column. This paper investigates using elastomeric materials in a RC pier to diminish or even eliminate above-mentioned factors. For this purpose, totally seven numerical piers under Kobe earthquake load and constant axial load were modeled in nonlinear finite element software. Elastomeric material was used in plastic hinge zone of RC pier in different heights and thicknesses. Base shear and ductility of piers were evaluated. Results generally showed that, using elastomeric material in a RC pier reduced ductility but it will decreased base shear force in size of 10.61 percent. The other advantage of using elastomeric material is to eliminate concrete tensile defect in tension surface of pier section and reinforcement bars corrosion due to concrete cover ruin in corrosive environment.
 
Article
In this study, an energy-based damage index (𝐷𝐼𝐸) was introduced and expressed as a simple formula on the basis of the nonlinear response obtained from nonlinear static procedures. The 𝐷𝐼𝐸 is advantageous because pushover analysis has to be performed only once for the lateral loads obtained from the equivalent static method given in the IS 1893 to represent the degree of damage to the structure under consideration. The 𝐷𝐼𝐸 was employed to assess the damage sustained by example RC frames representing different structures. To extend 𝐷𝐼𝐸 to different performance levels defined in the FEMA 356, the damage values were associated with the drift-based damage index. The results indicated that the 𝐷𝐼𝐸 concurred with drift-based damage criterion, and it is a valuable tool for practical applications.FEMA 356, the damage values were associated with the drift-based damage index. The results indicated that the𝐷𝐼𝐸 concurred with drift-based damage criterion, and it is a valuable tool for practical applications.
 
Dynamic amplification for plate subjected to the moving load
Central displacement of plate subjected to the different moving loads  
Article
This paper presents development of spectral finite strip method for dynamic analysis of thin rectangular plates subject to moving loads. Dynamic stiffness matrix of a plate strip in frequency domain is derived. For obtaining dynamic response of plate subjected to moving loads, both Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) are utilized. Numerical examples are presented to validate accuracy of the presented method.
 
Discretization of model  
Evolution of hydration rate as a function of time for different values of w/c  
COMSOLS's 3D velocity magnitude in the climatic chamber's air domain (m/s)  
effect of ambient temperature on the slab
Effect of ambient temperature on the slab temperature evolution  
Article
The early age behavior of concrete is a complex phenomenon because of the chemical, physical and mechanical characteristics that evolve in time, with climate being one of the essential conditions influencing this evolution. The objective of our present work is based on the study by numerical simulation, in 3- dimensions, of concrete behavior at an early age during the first 24 h of hydration under severe conditions of temperature and wind speed using a COMSOL Multi-physics. The temperature was maintained at 55°C for the first 7 h, then from the 8th hour to 24th hour decreasing down to 25°C, with a 12km/h wind speed. The model describes two divided domains air and the concrete slab. The obtained results allow us to better understand the temperature variation phenomena in the slab by heat transfer taking into account the release of heat due to the exothermic reactions of cement hydration as well as the influence of a high wind speed, while varying the thickness of the slab studied and the w/c ratio.
 
Article
The study presented in this paper develops a statistical model which could predict the failure mode of an RC interior beam-column connection under seismic load. A database has been compiled by assembling the details of 150 test specimens loaded to failure under quasi-static cyclic loading, selected from past research. Multinomial logistic regression was employed to develop the model to predict the joint response with three possible outcomes such as shear failure, beam failure and beam-joint failure. Performance analysis of six interior connection specimens, designed to be seismic-resistant with varying aspect ratios, concrete compressive strength, and beam bar yield strength, has validated the statistical model.
 
Article
Low-rise reinforced concrete (RC) buildings are common as dwelling houses in developing nations including the Indian subcontinent. Passive damper in the form of TLDs appear to be promising in seismic mitigation of such buildings. Apart from this, in day-to-day building design, the presence of masonry infill is generally ignored, except its mass. In the present study 1/4th scale 3-storey RC model building has been considered with and without infill panels for investigating the effectiveness of TLDs in vibration mitigation. A series of experimental tests has been carried out using a unidirectional shaking table under horizontal strong harmonic excitation. In the first phase the response mitigation on bare frame building model in with TLDs has been studied. In the second phase, building with infill panel has been tested incorporating TLDs. The present study shows that substantial response reduction is possible in low-rise RC buildings using TLDs as passive dampers.
 
Shell element provided with link beams Figure 6. Multi layered shell element in SAP2000
Acceleration-time history of N. Palm Spring 1986 0920, USGS station 5070
Formation of plastic hinge in beams, columns
Article
Frame - shear wall buildings are common for high rise multi-storied RC buildings. When these walls are situated in advantageous positions in a building, they perform as an efficient lateral-force resisting system, and also fulfilling other functional requirements. In conventional analysis, shear wall is modeled as wide column, which does not always provide the realistic behavior of a shear wall. In this present work, buildings have been modeled and designed, and a detailed analysis is carried out on structural walls. The building frame and length of shear wall design has been carried out by Unified Performance Based Design (UPBD) with takes both elastic and plastic rotation into consideration along with performance level. In this study shear walls are modeled as multi layered shell element which is an advanced addition in SAP2000 software. A few challenges in interpreting the performances of shear wall as per UPBD method were faced while using shell element. Non-linear analysis with shell element is carried out and attempts to interpret its performance in terms of stresses in different layers and hinge rotation have been carried out.
 
Article
Portland cement is widely used all over the world and the consumption is next to the consumption of water. The manufacturing of Portland cement emits large quantity of CO2 which causes pollution to the environment and makes serious impact on global warming. To reduce the emission of CO2 by way of replacing the cement concrete, an alternative concrete called Geopolymer Concrete (GPC) was introduced in the year 1980. GPC is a new class of concrete based on an inorganic alumino - silicate binder system compared to the hydrated calcium silicate binder system of Portland cement concrete. To produce the Geopolymer Concrete (GPC) an alkali - activator solution called alkaline liquid consists of sodium hydroxide (NaOH) and sodium silicate (Na2Sio3) is used as a catalyst to extract the silicon (Si) and Aluminium (Al) from the source material of Ground Granulated Blast Furnace Slag (GGBS) and Fly Ash (FA) which produce a binder like gel by polymerization which is similar to the gel of Portland cement concrete by hydration. NaOH in pellet form was dissolved in potable water and mixed with Na2 Sio3 in liquid form to prepare the alkaline solution. Four beams of M 60 grade of size 125 x 250 x 3200 mm were cast and tested for flexure. Out of these four beams, two beams are control beams with Portland cement concrete and the remaining two are GPC beams. The GPC beams were ambient cured and the control beams by water curing. Under reinforced sections were designed for both GPC and control beams. Cubes were cast to find out the compressive strength. The flexural behavior for all the four beams was compared. Flexural strength and compressive strength were found out.
 
Article
The behavior of storage tanks' analysis in seismic areas is of major importance because of the strategic nature of these works. The steel cylindrical tanks are the most susceptible to damage due to dynamic buckling during earthquakes. In this study, three criteria are used to estimate the critical peak ground acceleration caused the tank instability. The liquid inside the tank was modeled using specific Ansys's finite elements and fluid-structure interaction. The calculation includes modal and time history analysis, including material and geometric non-linearity. The result values are compared with standard code previsions as well as the results of previous numerical research, and show the need to improve code provisions.
 
Article
In this study optimal design of reinforced concrete cantilever retaining walls is performed under static and earthquake loading conditions utilizing the Colliding Bodies of Optimization (CBO), Enhanced Colliding Bodies of Optimization (ECBO) and vibrating particles system (VPS) methods. This design is based on ACI 318-05 and two theories known as Coulomb and Rankine have been applied for estimating the earth pressures under static loading condition, and Mononobe-Okabe method have been applied for estimating earth pressures under earthquake loading condition. The objective function considered is the cost of the retaining wall and this function is minimized subjected to design constraints. The performances of the CBO, ECBO and VPS and some other optimization algorithms are compared for the considered benchmark examples.
 
Four-point Bending Specimen and Simplified Stress State  
Article
A Finite Element Analysis has been applied to a type of four-point bending specimen with S/W=3 to determine which condition a pure mode II can be constructed. The ANSYS simulation results have demonstrated that conditions l1 = l4 and l2 = l3 could not guarantee a pure mode II case be generated. The ratio W/D and ratio a/W have a remarkable contribution to the formation of pure mode II. At W/D = 3.75 and a/W from 0.25 to 0.35, an almost perfect shear mode II can be achieved at the single crack tip region. When a/W varies 0.2 to 0.6, the specimen can also be treated as in pure shear mode II case if a 6 percent of the ratio KI /KII is acceptable. A KII expression in fifth-degree polynomials has been calibrated.
 
Article
RC coupled shear walls are known as one of the best and popular lateral load resisting structural systems. Most of the structural design codes have no seismic design considerations for base shear and fundamental vibration period. In current study finite element models were generated to provide a reliable data base to estimate the base shear and fundamental period. The differences between the behavior of in-plane and out-of-plane actions in these systems were investigated. In the final stage corrective coefficients will present according to analyses results. More accurate estimation of the demand makes more resistant structures against wind and earthquake loads.
 
Platform sacs model 
DAF for base shear (BS)
DAF for Overturning Moment (OTM)
Time history for overturning moment in X direction 
Time history for overturning moment in Y direction 
Article
Offshore platforms are in a rough environmental condition and therefore structural damages are undeniable for the aging platforms. These structural damages, which are the results of fatigue, corrosion and other unavoidable events, reduce the stiffness of the structure. When the stiffness of the structure decrease, the dynamic response of the structure is becoming important and must be investigated. In this research, dynamic behavior of an existing jacket platform in the Persian Gulf under extreme environmental condition is investigated by using random time domain simulation method to reach a reliable value for DAF in the extreme condition. Fifteen, 1hour storm, simulations for the water surface elevation is produced to capture the statistical properties of extreme sea condition. Time series of base shear and overturning moment are derived from both dynamic and static responses. By calculating the maximum DAF from each simulations and fitting the collected data to Weibull distribution, the Most Probable Maximum Extreme (MPME) value for the DAF is achieved. Results show that DAF for this type platform is a noticeable value and should be included in any analyses.
 
Article
Arches, vaults and domes are common features in the cultures of old civilizations. They were usually made of sun-dried bricks, fired bricks or stones with different types of mortar. The majority of these components are vulnerable to seismic effects. To present a viable study on their seismic vulnerability, all the factors influencing their behavior need to be investigated. In this paper, the construction materials used and the structural features of these elements are briefly described. Furthermore, the different aspects of using numerical methods for analyzing these elements are discussed. Finally, measures needed to improve their resistance are suggested.
 
The studied bundled framed tube: (a) plan of the structure including moment frames (Thick lines) and simple frames (Narrow lines); (C M and C S represent center of mass and center of shear respectively), (b) The model view, (c) Columns section properties of the 10-story model, (d) Beams section properties of the 10-story model 
The structural members of the 10 story studied model (in millimeters)
The key input parameters for interpolating and developing equivalent velocity pulses
The envelope of stories maximum velocity of floor at the center of mass CM in X direction (Fig. 1)
Article
In this paper, the performance of a medium-height bundled-tube structural system of 10 stories is studied under strong near-field records as well as produced equivalent mathematical pulses. Assessing analytical results of this research reveal the fact that floors drift in the studied model under natural records and also equivalent mathematical pulses, bring relatively similar results. Therefore, it is observed that by applying suitable closed-form models while acknowledging limitations, it is possible to simulate powerful near-field records through mathematical pulses and use them for the purpose of evaluating the seismic behavior in medium-height structural systems.
 
Concrete mixtures designed for the selected projects
Distribution of the number of components and specimens
Sensitivity of the NDT and strength to the cure effect  
Combined correlation between crushing strengths and NDT measured on structural components  
Relationships between strength « F » and NDT on specimens and components
Article
The quality of concrete of the most of Algerian construction sites is often low. In the case of low compressive strength results, non-destructive tests such as rebound hammer and ultrasonic pulse velocity are performed to check these results. Correlations curves from either equipment manufacturers or from the literature are used by quality control laboratories in order to estimate concrete strength. The estimation of strength based on these correlations is often subject to confusion and contradictory results when compared with the core test results. This clearly shows the need for appropriate correlations for concrete made with local materials and under local environmental conditions. The main objective of this paper is to propose appropriate simplified correlations for concretes made by local materials and for compressive strength levels reflecting the conditions and current practices on building sites in Algeria. This study presents some models established between destructive and individual or combined nondestructive tests (Rebound hammer and ultrasonic pulse velocity) in order to obtain a better estimation of concrete strength on site. The results show the reliability of the combined methods and the important difference in concrete strength estimation as compared to the models available in the literature.
 
Top-cited authors
A. Kaveh
  • Iran University of Science and Technology
Siamak Talatahari
  • University of Tabriz
Kiachehr Behfarnia
  • Isfahan University of Technology
Ali Heidari
  • Shahrekord University
Sreevidya Venkataraman
  • Sri Krishna College of Technology