Techno Press
Tp_Editing System.E (TES.E)
Login Search


scs
 
CONTENTS
Volume 34, Number 6, March25 2020
 

Abstract
Steel-concrete-steel sandwich composite wall is composed of two external steel plates and infilled concrete core. Internal mechanical connectors are used to enhance the composite action between the two materials. In this paper, the compressive behavior of a novel sandwich composite wall was studied. The steel trusses were applied to connect the steel plates to the concrete core. Three short specimens with different truss spacings were tested under compressive loading. The boundary columns were not included. It was found that the failure of walls started from the buckling of steel plates and followed by the crushing of concrete. Global instability was not observed. It was also observed that the truss spacing has great influence on ultimate strength, buckling stress, ductility, strength index, lateral deflection, and strain distribution. Three modern codes were introduced to calculate the capacity of walls. The comparisons between test results and code predictions show that AISC 360 provides significant underestimations while Eurocode 4 and CECS 159 offer overestimated predictions.

Key Words
truss spacing; sandwich composite wall; compressive behavior; strength

Address
Ying Qin, Xin Chen, Wang Xi, Xing-Yu Zhu and Yuan-Ze Che:Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education,
School of Civil Engineering, Southeast University, Nanjing, China


Abstract
The subject of the paper is a circular plate with symmetrically thickness-wise varying mechanical properties. The plate is simply supported and carries a concentrated force located in its centre. The axisymmetric bending problem of the plate with consideration of the shear effect is analytically and numerically studied. A nonlinear function of deformation of the straight line normal to the plate neutral surface is assumed. Two differential equations of equilibrium based on the principle of stationary potential energy are obtained. The system of equations is analytically solved and the maximum deflections and shear coefficients for example plates are derived. Moreover, the maximum deflections of the plates are calculated numerically (FEM), for comparison with the analytical results.

Key Words
circular plate; bending; functionally graded materials; shear effect; nonlinear theory

Address
Krzysztof Magnucki, Wlodzimierz Stawecki and Jerzy Lewinski: Lukasiewicz Research Network - Institute of Rail Vehicles TABOR,
ul. Warszawska 181, 61-055 Poznan, Poland


Abstract
Semi-rigid connections with blind bolts could solve the difficulty that traditional high strength bolts were unavailable to splice a steel/composite beam to a closed section column. However, insufficient investigations have focused on the performance of semi-rigid connection to square concrete filled double-skin steel tubular (CFDST) columns. In this paper, a component model was developed to evaluate the mechanical behavior of semi-rigid composite connections to CFDST columns considering the stiffness and strength of column face in compression and column web in shear which were determined by the load transfer mechanism and superstition method. Then, experimental investigations on blind bolted composite joints to square CFDST columns were conducted to validate the accuracy of the component model. Dominant failure modes of the connections were analyzed and this type of joint behaved semi-rigid manner. More importantly, strain responses of CFDST column web and tubes verified that stiffness and strength of column face in compression and column web in shear significantly affected the connection mechanical behavior owing to the hollow part of the cross-section for CFDST column. The experimental and analytical results showed that the CFDST column to steel-concrete composite beam semi-rigid joints could be employed for the assembled structures in high intensity seismic regions.

Key Words
square concrete-filled double skin steel tubular (CFDST); composite beam; semi-rigid; component model

Address
Lei Guo and Meng Zhang: School of Civil Engineering, Hefei University of Technology, Tunxi Road 193, Anhui Province, 230009, China
Jingfeng Wang: School of Civil Engineering, Hefei University of Technology, Tunxi Road 193, Anhui Province, 230009, China;
Anhui Civil Engineering Structures and Materials Laboratory, Tunxi Road 193, Anhui Province, 230009, China


Abstract
The effects of atmospheric thermal loads on the response of structural elements that are exposed to open environments have been recognized by research works and design specifications. The main source of atmospheric heat is solar radiation, which dominates the variation of the temperature of air, earth surface and all exposed objects. The temperature distribution along the depth of steel members may differ with the geometry configuration, which means that the different-configuration steel members may suffer different thermally induced strains and stresses. In this research, an experimental steel beam was instrumented with many thermocouples in addition to other sensors. Surface temperatures, air temperature, solar radiation and wind speed measurements were recorded continuously for 21 summer days. Based on a finite element thermal analysis, which was verified using the experimental records, several parametric studies were directed to investigate the effect of the geometrical parameters of AISC standard steel sections on their thermal response. The results showed that the overall size of the beam, its depth and the thickness of its elements are of significant effect on vertical temperature distributions and temperature differences.

Key Words
steel beam; environmental thermal loads; temperature; temperature difference; solar radiation

Address
Sallal R. Abid: Department of Civil Engineering, University of Wasit, Kut, Iraq

Abstract
This study aims to examine the interface shear behavior between precast high-strength concrete slabs with pockets and steel beam to achieve accelerated bridge construction (ABC). Twenty-six push-out specimens, with different stud height, stud diameter, stud arrangement, deck thickness, the infilling concrete strength in shear pocket (different types of concrete), steel fiber volume of the infilling concrete in shear pocket concrete and casting method, were tested in this investigation. Based on the experimental results, this study suggests that the larger stud diameter and higher strength concrete promoted the shear capacity and stiffness but with the losing of ductility. The addition of steel fiber in pocket concrete would promote the ductility effectively, but without apparent improvement of bearing capacity or even declining the initial stiffness of specimens. It can also be confirmed that the precast steel-concrete composite structure can be adopted in practice engineering, with an acceptable ductility (6.74 mm) and minor decline of stiffness (4.93%) and shear capacity (0.98%). Due to the inapplicability of current design provision, a more accurate model was proposed, which can be used for predicting the interface shear capacity well for specimens with wide ranges of the stud diameters (from13 mm to 30 mm) and the concrete strength (from 26 MPa to 200 MPa).

Key Words
push-out test; steel-precast slabs; grouped studs shear connector; high-strength concrete; accelerated bridge construction

Address
Zhuangcheng Fang, Haibo Jiang, Gongfa Chen, Xiaotong Dong and Tengfei Shao: School of Civil and Transportation Engineering, Guangdong Univ. of Technology,
Guangzhou Higher Education Mega Center, Guangzhou, 510006, China


Abstract
In recent years, due to the many advantages cable-stayed bridges have often constructed in medium and long span. These advantages can be listed as an aesthetically pleasing appearance, economic and easy construction, etc. The main structural elements of cable-stayed bridges are listed as deck, pylon, cables and foundation. Perhaps one of the most vital and expensive of these structural elements is stay-cables. Stay-cables ensure the allowable displacement and distribution of bending moments along the bridge deck with prestressing force. Therefore the optimum design of the stay-cables and prestressing force are very important in achieving the performance expected from the cable-stayed bridges. This paper aims to obtain the stay-cables size and prestressing force optimization of the cable-stayed bridge. For this purpose, single pylon and fan type cable configuration Manavgat Cable-Stayed Bridge was selected as an example. The three dimensional (3D) finite element model (FEM) of the bridge was created with SAP2000. Analysis of the 3D FEM of the bridge was conducted under the different combined effects of the self-weight of the structural element, prestressing force of stay-cable and live load. Stay-cable stress and deck displacement were taken into account as constraints for the optimization problem. To optimize this existing bridge a metaheuristic algorithm named Jaya was used in the optimization process. 3D FEM of the selected bridge was repeatedly analyzed by using Open Applicable Programming Interface (OAPI) properties of SAP2000. To carry out the optimization process the developed program which integrates the Jaya algorithm and the required codes for calling SAP2000 is coded in MATLAB. At the end of the study, the total weight of the stay-cables was reduced more than 40% according to existing stay cables under loads taken into account.

Key Words
SAP2000-OAPI; size optimization; prestressing force; cable-stayed bridge; Jaya algorithm

Address
Barbaros ATMACA and Tayfun DEDE: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey
Maksym GRZYWİNSKİ: Czestochowa University of Technology, Faculty of Civil Engineering, Czestochowa, Poland

Abstract
After medium or strong earthquakes, damage in the reduced portion of RBS connections occurs due to plastic deformations. The purpose of this paper is to numerically and experimentally investigate the reduced depth section connection as a replaceable fuse. In this regard, three commonly used rigid connections with RBS, a replaceable fuse with RBS, and a replaceable fuse with Reduced Depth Section (RDS-F) were evaluated. All specimens were subjected to quasi-static cyclic load until failure. Although the final strength of the RDS-F is lower than that of the other two, laboratory results showed that it had the maximum ductility among the three samples. The numerical models of all three laboratory samples were constructed in ABAQUS, and the results were verified with great accuracy. The results of more than 28 numerical analyses showed that the RDS-F sample is more ductile than the other specimens. Moreover, the thickness of the web and the plastic section modulus increasing, the final strength would be equal to the other specimens. Therefore, the modified RDS-F with replaceability after an earthquake can be a better alternative for RBS connections.

Key Words
steel moment resisting frame; rigid connection; replaceable fuse; beam with reduced depth section; beam with reduced flange section

Address
Allah Reza Moradi Garoosi: Department of Civil Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
Mehrzad Tahamouli Roudsari: Department of Civil Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
Behrokh Hosseini Hashemi: Structural Eng. Research Center, The Int\'l Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran

Abstract
This work features the outcomes of an empirical investigation into the characteristics of steel reinforced grout (SRG) composite - concrete interfaces. The parameters varied were loading rate, densities of steel fibres and types of load displacement responses or measurements (slip and machine grips). The following observations and results were derived from standard single-lap shear tests. Interfacial debonding of SRG - concrete joints is a function of both fracture of matrix along the bond interface and slippage of fibre. A change in the loading rate results in a variation in peak load (Pmax) and the correlative stress (max), slip and machine grips readings at measured peak load. Further analysis of load responses revealed that the behaviour of load responses is shaped by loading rate, fibre density as well as load response measurement variable. Notably, the out-of-plane displacement at peak load increased with increments in load rates and were independent of specimen fibre densities.

Key Words
bond properties; failure mode; steel reinforced grout (SRG); single-lap shear test; concrete substrate

Address
Hashem Jahangir and Mohammad Reza Esfahani: Department of Civil Engineering, Ferdowsi University of Mashhad, Azadi Square, Mashhad, Razavi Khorasan, Iran

Abstract
Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at 1/2 scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

Key Words
innovative elliptic bracing system; energy dissipation; hysteretic behavior; experimental behavior; seismic performance

Address
Habib Ghasemi Jouneghani and Abbas Haghollahi: Department of Civil Engineering, Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran

Abstract
This paper addresses the results of an experimental study involving 10 partially encased composite columns under concentric and eccentric compressive loads. Parameters such as slenderness ratio, ordinary reinforced concrete and fiber reinforced concrete, load eccentricity and bending axis were investigated. The specimens were tested to investigate the effects of replacing the ordinary reinforced concrete by fiber reinforced concrete on the load capacity and behavior of short and slender composite columns. Various characteristics such as load capacity, axial strains behavior, stiffness, strains on steel and concrete and failure mode are discussed. The main conclusions that may be drawn from all the test results is that the behavior and ultimate load are rather sensitive to the slenderness of the columns and to the eccentricity of loading, specially the bending axis. Experimental results also indicate that replacing the ordinary reinforced concrete by steel fiber reinforced concrete has no considerable effects on the load capacity and behavior of the short and slender columns and the proposed replacement presented very good results.

Key Words
partially encased composite columns; steel-concrete composite columns; experimental analysis; steel fiber reinforced concrete; concentric load; eccentric load

Address
Margot F. Pereira and Silvana De Nardin: Department of Civil Engineering, Federal University of Sao Carlos, Sao Carlos, Brazil,
Rodovia Washington Luís, km 235 - SP-310 São Carlos-SP - CEP 13565-905, Brazil
Ana L.H.C. El. Debs: Department of Structural Engineering, University of São Paulo, São Carlos, Brazil,
Avenida Trabalhador Saocarlense 400, Centro, São Carlos-SP - CEP: 13566-590, Brazil





Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2020 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-2-736-6801, Email: info@techno-press.com