cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.12755/isec.res.2017.136
title: Brittle/ductile assessment of Hybrid Reinforced Concrete beams containing steel rebar and fibers

description: Many structures, such as precast and cast-in-situ tunnel linings, are nowadays realized with Hybrid Reinforced Concrete (HRC), where a combination of continuous steel rebar and discrete fibers is used to reinforce the cementitious matrix. Hence, the definition of a minimum amount of hybrid reinforcement (i.e., rebar and fibers), which prevents the brittle failure, is of practical interest. For predicting the brittle/ductile response of HRC beams in bending, a theoretical model is introduced and presented in this paper. It is based on the flexural response of both Lightly Reinforced Concrete (LRC) and Fiber-Reinforced Concrete (FRC) beams, separately analyzed. The numerical results of the model, and some experimental data as well, show that the minimum reinforcement of HRC beams can be determined with a new design procedure. It requires the definition of the ductility index (DI), which is proportional to the difference between ultimate and effective cracking load. As DI linearly increases with the amount of rebar and fibers, the minimum reinforcement in HRC members can be found when DI is equal to zero. In addition, the minimum hybrid reinforcement can be defined with a suitable linear combination of the minimum area of rebar and the minimum fiber volume fraction, related to LRC and FRC beams, respectively.
DOI: 10.12755/isec.res.2017.137
title: Critical Comparison between two Strengthening Techniques of Reinforced Concrete Columns

description: In this work a comparison between different methodologies for the strengthening of concrete is made. In particular both concrete confined with FRP and concrete confined with angles and battens are considered. By comparing these two methodologies, it appears clear that a lot of limitations arise when FRP are used, in particular when the shape of the reinforced section is constituted by a rectangle having the ratio between the two sides that is greater than two. In fact, in this case the confining action due to FRP is negligible, while by means of steel bars passing through the section the use of traditional reinforcing methodology can be very effective. In addition to the confining effect, the angles can provide strengthening both in tension and in compression, depending on the structural detail adopted at the concrete floor slab.
DOI: 10.12755/isec.res.2017.138
title: Vulnerability Reduction of Steel Moment Resisting Frames by means of Reduced Beam Section

description: The idea and the developed example of this work is based on the attainment of seismic performance improvement by simply trimming the flanges of the beam ends. This strategy is to be applied by considering both the results of the theory of plastic mechanism control and the rules assuring the yielding of reduced beam sections (RBS) when seismic loads are applied to the structure. The results of such strategy is not always effective. In fact, there are several condition that are to be satisfied in order to obtain an actual seismic improvement. Notwithstanding, when these conditions are satisfied, the cost of intervention can be considered as negligible. For this reason this strategy can be very interesting and the rules applied in this work can clarify which is the effect of RBS taking into account all the parameters playing a role in the final design:, i.e. existing column sections, resistance and ductility of existing connections, vertical loads acting in seismic load combination, amount of the reduction of beam section and its distance from the connection.
DOI: 10.12755/isec.res.2017.139
title: Measuring crack width in RC and R/FRC ties throught laser scanner

description: Durability of reinforced concrete (RC) structure is strictly connected to the capacity of concrete mass to protect the embedded reinforcement from corrosion. As cracks are almost inevitable, crack width is a fundamental parameter that needs to be controlled during the serviceability stage of RC members. In fact, not only the direct ingress of aggressive agents, such as oxygen and water, is a function of crack width, but also concrete carbonation and the chloride ion penetration are accelerated by the presence of wide cracks. Accordingly, the aim of present research project is to assess the width by using a new system, based on the optical conoscopic holography. It provides the non-contact measure of crack profile, taken at the end of each loading cycle, in ties subjected to sets of repeated loads. Both in plain and fiber-reinforced concrete (FRC), more than one crack width can be mesured for the same crack.
DOI: 10.12755/isec.res.2017.140
title: EXPERIMENTAL STUDY ON THE STRUCTURAL BEHAVIOR OF FIRE PROTECTED DOUBLE CFT COLUMN SUBJECTED TO FIRE LOAD

description: New concrete filled double-tube (CFDT) sections consist of an inner and outer tube with fire protection mortar (FPM) filling the cavity between them and the inner tube also filled with concrete or not. An investigation into the fire performance of CFDT during the standard fire test is reported. Six full size FPM filled CFDT columns were designed for the fire tests. Detail failure modes of overall specimens and each component in the columns as well as temperature, deformation and fire endurance were presented. It showed that the fire resistance in the CFDT columns is significantly higher than that in concrete filled steel tubular (CFT) columns. Experimental investigation into the fire performance of the columns reveals possible solutions to improve the fire resistance of CFT members.
DOI: 10.12755/isec.res.2017.141
title: NUMERICAL ANALYSIS OF CONCRETE BEAMS REINFORCED WITH GLASS FIBER REINFORCED POLYMER BARS

description: The use of Fiber Reinforced Polymer (FRP) bars to reinforce concrete beams has received great attention in the past decade due to their corrosion resistance, high tensile strength, and excellent non-magnetic properties. Glass FRP (GFRP) reinforcing bars have gained popularity due to the relatively lower cost compared to Carbon FRP (CFRP) bars. In this study, sixteen concrete beam finite element models were created using the finite element computer program ANSYS to perform linear and non-linear analyses. Twelve beams were longitudinally reinforced with GFRP bars, while the remaining four beams were reinforced with conventional steel bars as control specimens. In terms of mechanical properties, FRP reinforcing bars have lower modulus of elasticity compared to conventional reinforcing steel and remain linear elastic up to failure. This leads to lack of plasticity and a brittle failure of beams reinforced with FRP bars. The objective of this study is to investigate flexural behavior of concrete beams reinforced with GFRP reinforcing bars. Some of the parameters incorporated in the numerical analysis include longitudinal reinforcement ratio and compressive strength of concrete, both of which affect the flexural capacity of beams. It is shown in this study that replacement of traditional reinforcing steel reinforced bars by GFRP bars significantly decreases mid-span deflection and increases ultimate load. The strain distribution along GFRP longitudinal reinforcing bars is totally different from that of traditional steel bars.
DOI: 10.12755/isec.res.2017.142
title: Reinforced concrete crack model based on stiffness analysis of tension members

description: The average spacing of primary cracks in a reinforced concrete (RC) member greatly influences its in-service behavior, especially with regard to stiffness and average crack width. Accurate predictions of the average crack spacing are therefore crucial for satisfying serviceability requirements in RC structures. This is particularly the case when relying on analytical models that treat cracks discretely rather than in a smeared fashion. Popular code-based models for primary crack spacing are often wildly inaccurate and may lead to poor predictions of in-service behavior. In this paper, the problem or primary crack formation is approached from a stiffness perspective. The proposed model is based on the results of several experimental tension stiffening studies in the literature, as well as a previous numerical study dealing with the effect on stiffness of non-plane deformation in the neighborhood of primary cracks. The proposed model is compared to some popular code-based models and is shown to better predict average crack spacing for a wide variety of beams, slabs, and tension members.
DOI: 10.12755/isec.res.2017.143
title: Interaction strength for CHS-to-longitudinal plate joints under axial load and in-plane bending moment

description: The circular hollow section (CHS) has lots of advantages in excellent structural properties, architecturally attractive features. Thus CHS are used extensively in many applications in buildings, bridges, towers, and offshore. In CHS, it is necessary to understand the various complex shape of CHS joint because loads act simultaneously according to joint type. The use of high strength steel has been continuously increased, but the current design equation in AISC 2011 or KBC 2016 limits maximum yield strength 360MPa. This paper studies an interaction strength of high strength CHS-to-longitudinal plate X-joint subjected to combination of plate axial load and in-plane bending moment. For the study, numerical analysis based on experimental tests was carried out. The analysis was performed according to variables for determining shape of joint, i.e., chord slenderness, plate width-to-CHS diameter ratio, and utilization ratio. Investigations have shown that a linear summation of the ratios for axial load and in-plane bending moment may be used as conservative approximation.
DOI: 10.12755/isec.res.2017.144
title: EXPERIMENTAL STUDY OF BEAM WITH EMBOSSED WEB

description: In order to reduce the weight and the material cost in the steel structures, a study on the slender sectional design has been continuously carried out. Steel beams with corrugated web have been widely used in the steel structures. The welding part between the corrugated web and the flange, however, is not straight, which makes the production costs increased. In order to compensate for this drawback, steel beam with an intaglio and embossed web (IEB) was invented by Innovation & Smart Heavy Industry Co., Ltd., South Korea. Plain plate is pressed to keep the upper and lower boundary of the web straight. This makes it possible to weld the flange and the embossed web by the automatic welding machine. In this study, four types of specimens were tested for comparison with plain H-shaped steel beam. Experimental results showed that the maximum load of the IEB specimens is about 1.3 times larger than that of the H-shaped steel beams. This is because the tension field action of embossed web significantly increased the post-buckling strength.
DOI: 10.12755/isec.res.2017.145
title: A method for static analysis of cable-stayed structures subjected to in-plane loads

description: Present cable theory which formulated from force balance equation of single cable under self-weight and forms a catenary shape of deflection, that is nonlinear; therefore to determine displacement, deformation and tension forces of the cable and cable-stayed structures we need to provide some additional assumptions of cables and use iteration calculation. This paper presents a new method for static analysis of cable-stayed structures subjected to in-plane loading. By combination of the Gaussian Extreme Principle method and virtual displacement principle, authors to formulate and solve nonlinear equation system of cable-stayed structures, which ensured forces balancing as well as continuity of displacements and deformations of structures. This method allows for simultaneous determination of displacement, deformation and internal forces of cable-stayed structures without any other additional hypothesis, which is different from present cable theory.
DOI: 10.12755/isec.res.2017.146
title: A rational method for computation of cable structures

description: Cable structures are widely used in construction of suspension bridges, cable-stayed bridges, suspension roofs, etc. due to its advantages of light weight, high strength which allow to build large span structures with nice view. To date still use classical theory of flexible cable which form the deflection shape of catenary or parabola when cable subjected to uniformly distributed load along cable length or over the span. The classical theory cable formulated from force balance equation of single cable, that is nonlinear; therefore, to determine displacement, deformation and tension forces of the cable we need to provide cable dip or horizontal tension force and use iteration calculation. This paper presents a new method for computation of flexible cable subjected to different loading pattern including concentrated force, distributed forces, pretension force, temperature variation. By application of the Gaussian Extreme Principle method, which developed by Prof. Drs. Ha Huy Cuong, to formulate and solve nonlinear equation system of cable structures, which ensured forces balancing as well as continuity of displacements and deformations of cable structures. This method allows for simultaneous determination of displacement, deformation and tension forces of cable structure without any other additional hypothesis, which is different from present cable theory. Numerical examples with simple, flexible cables subjected to different loadings have indicated the simplicity, accuracy and stability of the proposed method.
DOI: 10.12755/isec.res.2017.147
title: Estimation of Vehicular Collision Force for Bridge Columns using Computational Models

description: Although not commonly occurring, collisions of heavy vehicles with highway overpass bridge columns have happened in the past and resulted in catastrophic structural failures that paralyzed traffic on both the overpass and the highway below. A study that was conducted at South Dakota State University performed risk assessment and developed mitigation strategy for vehicular collision with bridge columns on South Dakota interstate highways. Since the collision force is dependent upon the stiffness of the structure and the approach speed of the crashing truck, a finite element (FE) dynamic analysis was performed in the study to evaluate the collision forces resulting from two different truck sizes crashing into a prototype bridge bent at three different approach speeds (55 mph, 65 mph, 75 mph). This paper covers the FE simulation that was performed using a computer software. The results indicate that the 600-kip vehicular collision force specified by AASHTO is a reasonable estimate for the load demand induced by an 80,000 lb tractor-trailer crashing into a bridge column at an approach speed not exceeding 55 mph.
DOI: 10.12755/isec.res.2017.148
title: NUMERICAL PARAMETRIC STUDIES FOR THERMOGRAPHIC INSPECTION IN CONCRETE

description: Thermographic imaging technique provides a practical tool for the detection of subsurface delaminations in concrete from a distance without direct access to the surface. In the previous study, a numerical model to predict the thermal contrasts resulting from subsurface voids (i.e., delaminations) in concrete under a given set of environmental conditions was developed using the finite element method. The model was verified using the experimental test data, and the results indicated that the model could be an effective tool to support the thermography inspection of the concrete. In this present study, the use of the verified model to evaluate the effects of other key parameters expected to influence the detectability of the subsurface voids, such as the depth and thickness of a subsurface delamination. The effect of these parameters on the thermal contrast developed on the surface above a subsurface delamination was assessed under a specific set of environmental conditions. The results shown that the maximum thermal contrast decreased exponential by a constant multiple of 0.98 as the void depth increased and the maximum thermal contrast increased nonlinearly with increasing thickness of the void.
DOI: 10.12755/isec.res.2017.149
title: A RETROFIT METHOD FOR OLD PRECAST PANEL BUILDINGIN ULAANBAATAR, MONGOLIA

description: This study is devoted to the development of improved methods and computer programs for predicting the seismic performance of existing precast panel structures. It is necessary to establish an experimental investigation as well as to develop a more detailed analysis and design procedures related to seismic design considerations for existing precast panel structures. The nonlinear behavior of precast panel buildings depends on the panel contact zones and this feature should be incorporated into the analytical models for the elasto-plastic nonlinear analysis. This study presents a newly designed finite element program developed on Fortran software for the nonlinear analysis of typical precast panel buildings. With the aid of this finite element program, eight different analytical models were designed and performed to simulate the nonlinear behaviors of panel contact zones under lateral loading. The analytical models were composed of four control models without any retrofitting and four models retrofitted using a steel bolted plates at the both horizontal and vertical joints between associated panels. A two-dimensional elasto-plastic nonlinear analysis with pushover method was performed on the analytical models, to obtain lateral force and displacement relationship. The simulation results illustrate the comparisons of lateral force-displacement curves for both the non-retrofitted and the retrofitted models. It was observed that all the retrofitted models showed a significant increase in strength and ductility.
DOI: 10.12755/isec.res.2017.150
title: SHRINKAGE AND CREEP EFFECT ANALYSES OF DOUBLE COMPOSITE CONTINUOUS BOX-GIRDER BRIDGE CONSTRUCTED BY PRE-JACKING METHOD

description: Continuous double steel and concrete composite beam is a new structural system developed on the basis of common steel and concrete composite beam. Controlling concrete slab crack width in a continuous double composite beam is a significant content in the bridge construction process. Jacking-up and landing bearing supports method is applied to a double composite girder bridge construction and its structural mechanical behaviors in the whole process will be simulated. By using of User Programmable Features and ANSYS Parametric Design Language, the commercial FEM software ANSYS was further developed. The exponential model of concrete creep and the implicit solution of concrete creep equation under the action of variable stress were introduced into ANSYS, to realize the concrete shrinkage and creep effect analysis of double composite continuous box-girder bridges constructed by pre-jacking method. The results show that it is improved that the stress state of the top concrete slab in the negative moment regions by pre-jacking method. Due to the effect of concrete creep, the concrete creep will cause tensile stress in the negative moment regions of the composite beam, which will reduce the compressive stress in the top concrete slab. The effect of prestressing is greatly affected by pre-jacking value, and the creep of the concrete also causes the stress redistribution of the concrete and the steel beam.
DOI: 10.12755/isec.res.2017.151
title: EVALUATIONS OF FLEXURAL CAPACITY IMPROVEMENT METHOD FOR RC PIERS AND CISS FOUNDATION CONNECTIONS IN BRIDGES

description: Recently, Cast-In-Steel Shell(CISS) pile has been used as the foundation of bridges and a pier is directly connected to the pile. In this case, plastic hinge is generally formed at the connection between the CISS pile and reinforced concrete pier. To increase the flexural capacity of such structure, a proper improvement method is necessary for the connection. In this study, a steel tube, a steel pipe that has 270mm diameter with 4.5mm thickness, has been used to enhance flexural capacity of the connection and the effect by the such method was evaluated through cyclic compression-bending test. From the test results, it can be found that the flexure capacity is considerably increased by applying the steel tube at the connection when it was compared to a general RC pier with 10% larger diameter cross-section.
DOI: 10.12755/isec.res.2017.152
title: ANALYSIS OF SPACE FRAMES WITH GENERALIZED SEMI-RIGID CONNECTIONS

description: A mechanical model and analytic method are proposed, in which, the axial, the shearing and the bending semi-rigid characteristics of space frames are taken into account. An independent zero-length connection element comprising six translational and rotational springs is used to simulate the beam-to-column connection. The model, namely six-spring mechanical model, has an advantage that the element number of structure does not increase. The matrix displacement method is used to analyze mechanism of the model, including element analysis and structural analysis. The stiffness matrix of the element is derived. Some reaction forces at the end of the element are obtained when it is subjected to two kinds of different loads respectively. The obtained stiffness matrix gets the characteristics of symmetry and singularity and that makes the size of total stiffness matrix for semi-rigid frame the same as that for frame with rigid joints.
DOI: 10.12755/isec.res.2017.153
title: INFLUENCE OF TIE BEAMS ON THE SEISMIC PERFORMANCE OF TWO-COLUMNED HIGH PIERS

description: Two-columned high piers are widely used to continuous rigid frame bridges. The longitudinal flexural stiffness of high piers with height of over 40m is generally smaller, so tie beams are usually set between two columns to decrease the calculating height of piers to improve the stability behavior. In addition, under the seismic action, tie beams generally yield before columns, forming the plastic hinge and dissipating seismic energy, which decreases the damage of piers. To study the seismic performance of two-columned high piers with tie beams, nonlinear static and quasi-static analysis of a typical two-columned high piers with height 45m was conducted by two and three-dimensional finite element modeling techniques respectively. Factors of the longitudinal reinforcements and stirrups ratio of tie beams, the stiffness ratio of tie beams to columns and the number of tie beams on the seismic performance of high piers are all discussed. Analysis results show that the seismic performance two-columned high piers is effectively improved with increasing the number of tie beams and setting the stiffness ratio of tie beams to columns in a certain range, while there is little influence of the reinforcement ratio of tie beams. As a result, setting a reasonable number of tie beams is an effective way to improve the seismic performance of two-columned high piers.
DOI: 10.12755/isec.res.2017.154
title: RELATIONSHIP BETWEEN BATTENED BUILT-UP COLUMNS AND FRAMES ABOUT BUCKLING

description: The objective of this study is to examine the relationship between battened built-up columns and frames about buckling. Especially, the characteristics of the Bleich