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CONTENTS
Volume 16, Number 3, March 2019
 

Abstract
The efficacy of a galvanized steel wire mesh (GSWM) as an alternative material for the rehabilitation of RC beamcolumn connections damaged due to reversed cyclic loading was investigated. The repair mainly uses epoxy resin infused under pressure into the damaged zone and then confined using three types of locally available GSWM mesh. The mesh types used herein are (a) Weave type square mesh with 2mm grid opening (GWSM-1) (b) Twisted wire mesh with hexagonal opening of 15 mm (GSWM-2) and (c) welded wire mesh with square opening of 25 mm (GSWM-3). A reduced scale RC beam-column connection detailed as per ductile detailing codes of Indian Standard was considered for the experimental investigation. The rehabilitated specimens were also subjected to similar cyclic displacement. Important parameters related to seismic capacity such as strength, stiffness degradation, energy dissipation, and ductility were evaluated. The rehabilitated connections exhibited equal or better performance and hence the adopted rehabilitation strategies could be considered as satisfactory. Confinement of damaged region using GSWM-1 significantly enhanced the seismic capacity of the connections.

Key Words
beam-column connections; rehabilitation; Epoxy resin injection; galvanized steel wire mesh; seismic capacity

Address
Comingstarful Marthong: Department of Civil Engineering, National Institute of Technology Meghalaya, Shillong 793003, India

Abstract
Framed masonry wall structures represent a typical high-rise structural system that are also seismically vulnerable. During ground motions, they are excited in both in-plane and out-of-plane terms. The interaction between the frame and the infill during ground motion is a highly investigated phenomenon in the field of seismic engineering. This paper presents a numerical investigation of two distinct static out-of-plane loading methods for framed masonry wall models. The first and most common method is uniformly loaded infill. The load is generally induced by the airbag. The other method is similar to in-plane push-over method, involves loading of the frame directly, not the infill. Consequently, different openings with the same areas and various placements were examined. The numerical model is based on calibrated in-plane bare frame models and on calibrated wall models subjected to OoP bending. Both methods produced widely divergent results in terms of load bearing capabilities, failure modes, damage states etc. Summarily, uniform load on the panel causes more damage to the infill than to the frame; openings do influence structures behavior; three hinged arching action is developed; and greater resistance and deformations are obtained in comparison to the frame loading method. Loading the frame causes the infill to bear significantly greater damage than the infill; infill and openings only influence the behavior after reaching the peak load; infill does not influence initial stiffness; models with opening fail at same inter-storey drift ratio as the bare frame model.

Key Words
computational evaluation; experimental methodologies; out-of-plane behavior; framed-masonry walls; openings

Address
Filip Anic, Davorin Penava: Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek, Osijek 31000, Croatia
Lars Abrahamczyk: Earthquake Damage Analysis Centre (EDAC), Bauhaus-Universität Weimar, Weimar D-99421, Germany
Vasilis Sarhosis: School of Engineering, Newcastle University, Newcastle upon Tyne, NE4 5TG, UK

Abstract
The overall seismic performance of existing pre 1960-70s reinforced concrete (RC) structures is significantly affected by the inadequate length of columns\' lap-spliced reinforcement. Due to this crucial structural deficiency, the cyclic response is dominated by premature bond - slip failure, strength and stiffness degradation, poor energy dissipation capacity and low ductility. Recent earthquakes worldwide highlighted the importance of improving the load transfer mechanism between lapspliced bars, while it was clearly demonstrated that the failure of lap splices may result in a devastating effect on structural integrity. Extensive experimental and analytical research was carried out herein, to evaluate the effectiveness and reliability of strengthening techniques applied to RC columns with lap-spliced reinforcement and also accurately predict the columns\' response during an earthquake. Ten large scale cantilever column subassemblages, representative of columns found in existing pre 1970s RC structures, were constructed and strengthened by steel or RC jacketing. The enhanced specimens were imposed to earthquake-type loading and their lateral response was evaluated with respect to the hysteresis of two original and two control subassemblages. The main variables examined were the lap splice length, the steel jacket width and the amount of additional confinement offered by the jackets. Moreover, an analytical formulation proposed by Tsonos (2007a, 2019) was modified appropriately and applied to the lap splice region, to calculate shear stress developed in the concrete and predict if yielding of reinforcement is achieved. The accuracy of the analytical method was checked against experimental results from both the literature and the experimental work included herein.

Key Words
lap splices; bond-slip; retrofit; steel jacket; RC jacket

Address
George I. Kalogeropoulos and Alexander-Dimitrios G. Tsonos: Department of Civil Engineering, Aristotle University of Thessaloniki, GR-54-124 Thessaloniki, Greece

Abstract
This study attempts to develop new simplified approximate formulas to predict the fundamental natural periods of vibration (T) for bearing wall systems engaged with special reinforced concrete shear walls (RCSW) under seismic loads. Commonly, seismic codes suggested empirical formulas established by regression analysis of measured T for buildings during earthquake motions. These formulas depend on structure type, building height, number, height and length of SW, and ratio of SW area to base area of structure. In this study, a parametric investigation is performed for T of 110 selected models of bearing RCSW systems with varying structural height, configuration of horizontal plans including building width, number and width of bays, presence of middle corridors and core SWs. For this purpose, a 3D non-linear response time history (TH) analysis is implemented using ETABS v16.2.1. New formulas to estimate T are anticipated and compared with those obtained from formulas of IBC 2012 and ASCE/SEI 7-10. Moreover, the study examines responses of an arbitrarily two selected test model of 60 m and 80 m in height with presence of SWs having middle corridors. It is observed that the performance of the tested buildings is different through arising of considerable errors when using codes

Key Words
seismic codes; fundamental period; bearing walls, RC shear walls, non-linear time history

Address
Anis S. Shatnawi, Esra\'a H. Al-Beddawe and Mazen A. Musmar: Department of Civil Engineering, The University of Jordan, Amman-11942, Jordan

Abstract
Obelisks are historical monuments. There are several obelisks dating from ancient Egyptian period, located around various parts of the world. The city of Istanbul is a home to the Obelisk of Theodosius at the Hippodrome. Due to the expectation of a large event in the near future, the evaluation of seismic response of the Obelisk gets importance. Therefore, in this study structural dynamic behavior of the Obelisk was investigated using discrete element approach. Nonlinear dynamic analyses were performed using real and synthetic time series. Real and synthetic ground motions analyzed from this study seems consistent with the earthquake hazard levels that would be expected at the site of the Obelisk in the occurrence of an event of moment magnitude above 7.0 near Istanbul. Results are evaluated in terms of variation of displacement, relative displacement of adjacent blocks, normal stress and shear stress in time.

Key Words
obelisk; discrete element modelling; nonlinear dynamic analysis

Address
Ozden Saygili: Department of Civil Engineering, Yeditepe University, 26 Agustos Campus, Kayisdagi St., 34755, Atasehir, Istanbul, Turkey

Abstract
This study investigated the possibility of using the recorded micro tremor data on ground level as ambient vibration input excitation data for investigation and application Operational Modal Analysis (OMA) on the bench-scale earthquake simulator (The Quanser Shake Table) for model chimney. As known OMA methods (such as EFDD, SSI and so on) are supposed to deal with the ambient responses. For this purpose, analytical and experimental modal analysis of a model chimney for dynamic characteristics was performed. 3D Finite element model of the chimney was evaluated based on the design drawing. Ambient excitation was provided by shake table from the recorded micro tremor ambient vibration data on ground level. Enhanced Frequency Domain Decomposition is used for the output only modal identification. From this study, best correlation is found between mode shapes. Natural frequencies and analytical frequencies in average (only) 1.996% are different.

Key Words
experimental modal analysis; chimney; modal parameter; EFDD; shake table

Address
Sertac Tuhta: Faculty of Engineering, Department of Civil Engineering, Ondokuz Mayis University, Atakum/Samsun, Turkey

Abstract
The main objective of this experimental research was to investigate the Seismic performance of reinforced concrete frames infilled with perforated clay brick masonry wall of a type commonly used in Algeria. Four one story-one bay reinforced concrete infilled frames of half scale of an existing building were tested at the National Earthquake Engineering Research Center Laboratory, CGS, Algeria. The experiments were carried out under a combined constant vertical and reversed cyclic lateral loading simulating seismic action. This experimental program was performed in order to evaluate the effect and the contribution of the infill masonry wall on the lateral stiffness, strength, ductility and failure mode of the reinforced concrete frames. Numerical models were developed and calibrated using the experimental results to match the load-drift envelope curve of the considered specimens. These models were used as a bench mark to assess the effect of normalized axial load on the seismic performance of the RC frames with and without masonry panels. The main experimental and analytical results are presented in this paper.

Key Words
masonry infill panel; seismic performance; strength; stiffness; ductility; failure mode

Address
Hassan Aknouche, Abdelhalim Airouche and Hakim Bechtoula: National Earthquake Engineering Research Centre, C.G.S., Rue Kaddour RAHIM, BP 252 Hussein Dey, Alger, Algeria

Abstract
Long span cable-stayed bridges are extremely vulnerable to dynamic excitations such as which caused by traffic load, wind and earthquake. Studies on cable-stayed bridge vibration control have been keenly interested by researchers and engineers in design new bridges and assessing in-service bridges. In this paper, a novel Hybrid-Tuned Mass Damper (H-TMD) is proposed and a hybrid control model named Mixed Logic Dynamic (MLD) is employed to build the bridge-H-TMD system to mitigate the vibrations. Firstly, the fundamental theory and modeling process of MLD model is introduced. After that, a new state switching design of the H-TMD and state space equations for different states are proposed to control the bridge vibrations. As the state switching designation presented, the H-TMDs can applied active force to bridge only if the structural responses are beyond the limited thresholds, otherwise, the vibrations can be reduced by passive components of dampers without active control forces provided. A new MLD model including both passive and active control states is built based on the MLD model theory and the state switching design of H-TMD. Then, the case study is presented to demonstrate the proposed methodology. In the case study, the control scheme with H-TMDs is applied for a long span cable-stayed bridge, and the MLD model is established and simulated with earthquake excitation. The simulation results reveal that the suggested method has a well damping effect and the established system can be switched between different control states as design excellently. Finally, the energy consumptions of H-TMD schemes are compared with that of Active Tuned Mass Damper (ATMD) schemes under variable seismic wave excitations. The compared results show that the proposed H-TMD can save energy than ATMD.

Key Words
cable-stayed bridge; hybrid control; H-TMD; MLD; ATMD; state switching

Address
Bing Han: School of Civil Engineering, Beijing Jiaotong University, No.3, Shangyuancun, Haidian district, Beijing 100044, China; Key Laboratory of Safety and Risk Management on Transport Infrastructures, Ministry of Transport, PRC, Beijing 100044, China
Wu Tong Yan, Viet Hung Cu, Li Zhu and Hui Bing Xie: School of Civil Engineering, Beijing Jiaotong University, No.3, Shangyuancun, Haidian district, Beijing 100044, China

Abstract
This paper focuses on the study of dynamic analysis of thick plates resting on Winkler foundation. The governing equation is derived from Mindlin\'s theory. This study is a parametric analysis of the reflections of the thickness / span ratio, the aspect ratio and the boundary conditions on the earthquake excitations are studied. In the analysis, finite element method is used for spatial integration and the Newmark-B method is used for the time integration. While using finite element method, a new element is used. This element is 17-noded and it\'s formulation is derived from using higher order displacement shape functions. C++ program is used for the analyses. Graphs are presented to help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that the 17-noded finite element is used in the earthquake analysis of thick plates. It is shown that the changes in the aspect ratio are more effective than the changes in the aspect ratio. The center displacements of the reinforced concrete thick clamped plates for b/a=1, and t/a=0.2, and for b/a=2, and t/a=0.2, reached their absolute maximum values of 0.00244 mm at 3.48 s, and of 0.00444 mm at 3.48 s, respectively.

Key Words
free vibration analysis; forced vibration analysis; Newmark method; Mindlin

Address
Yaprak I. Ozdemir: Department of Civil Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey

Abstract
Construction industry is one of the largest markets for composite materials. Composite materials are mostly utilized as surface coatings or concrete reinforcements, and they can hardly be found as a load bearing member in buildings. The threedimensional composite structures with considerable bending, compressive and shear strengths are capable to be used as construction load bearing members. However, these composites cannot compete with other materials due to higher manufacturing costs. If the cost issue is resolved or their excellent performance is taken into consideration to overcome disadvantages related to economic-competitive challenges, these 3D composites can significantly reduce the construction time and result in lighter and safer buildings. Sandwich composite panels reinforced with 3D woven glass fabrics are amongst composites with highest bending strength. The current study investigates the possibility of utilizing these composite materials to construct ceilings and their application as slabs. One-to-one scale experimental loading of these composite panels shows a remarkable bending strength. Simulation results using ABAQUS software, also indicate that theoretical predictions of bending behavior of these panels are in good agreement with the observed experimental results.

Key Words
composite; sandwich panel; three-dimensional; building

Address
S.A. Sabet, R. Kolahchi: Department of Civil Engineering, Islamic Azad University, Kashan Branch, Kashan, Iran
Sh. Nazari, M. Akhbari: Department of Textile Engineering, Islamic Azad University, Kashan Branch, Kashan, Iran

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