پایگاه تخصصی عمران ایران

مقاله انگلیسی- DAMAGE AND PLASTICITY FOR CONCRETE BEHAVIOR

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شماره فایل : 108

 مقاله انگلیسی- DYNAMIC RESPONSE CHARACTERISTIC OF REINFORCED

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شماره فایل : 106

DYNAMIC RESPONSE CHARACTERISTIC OF REINFORCED CONCRETE COLUMN SUBJECTED TO BILATERAL EARTHQUAKE GROUND MOTIONS

SUMMARY

This paper presents the dynamic response characteristics of a reinforcement concrete column subjected to bilateral earthquake ground motions. A Series of shaking table tests and fiber model analyses were conducted for 3 cross-sectional types of columns. The experimental results showed that the effect of bilateral excitation of the column was found to be significant on the non-linear response behavior of the column. Furthermore, it was found that the fiber element model analysis could simulate the experimental results well before the deterioration of the strength of the columns caused by the buckling of longitudinal reinforcement and the peeling of cover concrete.

مقاله انگلیسی- Building Damage in May 26, 2003 Miyagi-Offshore Earthquak

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شماره فایل : 107

Building Damage in May 26, 2003 Miyagi-Offshore Earthquake

ABSTRACT

This paper reports the damage survey on building structures at the Miyagi-Offshore

Earthquake occurred on May 26, 2003. The maximum ground acceleration recorded at the

K-net strong motion observation stations was large and its response spectrum in the shorter

period exceeds the requirement of the Seismic Building Standard, but the structural damage to buildings was observed not so severe. The reason of the phenomena was discussed.

KEYWORDS: Miyagi-Offshore Earthquake, damage survey to buildings, strong motion records, response

مقاله انگلیسی- Deformation Behavior of Fiber-Reinforced Polymer Reinf

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شماره فایل : 105

Deformation Behavior of Fiber-Reinforced Polymer Reinforced Engineered Cementitious Composite (ECC) Flexural Members under Reversed Cyclic Loading Conditions

This study investigates the response of fiber-reinforced polymer (FRP) reinforced engineered cementitious composite (ECC) members with a focus on their flexural load-deformation behavior, residual deflection, damage evolution, and failure mode. Critical aspects of conventional FRP-reinforced concrete members—such as interfacial bond strength, flexural crack formation, composite deformation behavior, and brittle failure mode—are briefly reviewed and compared to FRP reinforced ECC. The interaction of linear elastic FRP reinforcement and ECC matrix with ductile stress-strain behavior in tension results in nonlinear elastic flexural response characteristics with stable hysteretic behavior, small residual deflection, and ultimately gradual compression failure. Compatible deformations of reinforcement and matrix lead to low interfacial bond stress and prevent composite disintegration by bond splitting and cover spalling. Furthermore, flexural stiffness and strength as well as crack formation and widths in FRP-reinforced ECC members are found effectively independent of interfacial bond properties due to the tensile deformation characteristics of the cementitious matrix. A model for the load-deflection envelope based on a nonlinear moment-curvature relationship is suggested.

Keywords: bond; composite; deformation; reinforcement; tolerance.

104- مقاله انگلیسی- ELASTIC-PLASTIC ANALYSIS OF RC SHEAR WALL USING

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شماره فایل : 104

ELASTIC-PLASTIC ANALYSIS OF RC SHEAR WALL USING DISCRETE ELEMENT METHOD

Abstract:

 An analytic method of RC structure using discrete element method is introduced in this paper. The RC structures are meshed with concrete discrete elements and re-bar elements. The discrete elements are connected with “point to point” contact elements and spring elements. The damage of concrete is assumed that it only happens on the interfaces of different discrete elements. Hence, the contact estimation of traditional discrete element method is simplified and the stability and speed of calculation process is improved. The influence of crack surfaces also can be obtained in this method, which is difficult for normal finite element method. A two-limb shear wall model is analyzed using this method. The results show this method is rational and effective.

Key Words: Discrete Element, Shear Wall, Elastic-plastic Analysis

103- مقاله انگلیسی- A new approach to the confinement of RC columns

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شماره فایل : 103

A new approach to the confinement of R/C columns

Abstract

A new constitutive law is presented, valid for confined concrete. The transversal stresses induced by a hoop, either of square or of circular shape, in the cross section of r.c. members (columns or beams) axially loaded, are evaluated through Airy's functions relevant to plain strain states. The results, valid for square or circular hoops, are then extended to hoops of polygonal shape, with or without bindings, and to a combination of hoops of different shapes. The formulation, valid for the cross section containing the hoop, is finally extended to the overall volume of the member through the interaction among hoops and longitudinal reinforcements. The results suggested by the proposed model for members of circular and square cross section are compared with experimental data and with the results of other researchers. The proposed model, in comparison with other models, shows a better agreement with experimental results.

KEYWORDS

Reinforced concrete, confinement, ductility

101- مقاله انگلیسی-APPLICATION OF PUSHOVER ANALYSIS ON REINFORCED CONCRETE B

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شماره فایل : 101

APPLICATION OF PUSHOVER ANALYSIS ON REINFORCED

CONCRETE BRIDGE MODEL

Abstract

This report describes a non-linear static (pushover) analysis method for prestressed reinforced concrete structures that predicts behavior at all stages of loading, from the initial application of loads up to and beyond the collapse condition. A look insight into pushover methodology described in EC8, FEMA-273/356 and ATC-40 documents also is presented. The nonlinear static (pushover) analysis method (NSP), developed here use “line elements” approach, and are based on the degree of refinement in representing the plastic yielding effects. The elasto-plastic behavior is modeled in two types: (1) distributed plasticity model, when it is modeled accounting for spread-of-plasticity effects in sections and along the beam-column element and (2) plastic hinge, when inelastic behavior is concentrated at plastic hinge locations. Both local (P-δ) and global (P-Δ) nonlinear geometrical effects are taken into account in analysis. The method has been developed for the purpose of investigating the collapse behavior of a three span prestressed reinforced concrete bridge of 115 meters in total length that is to be built in the northeastern of Portugal over Alva River. Performance of this bridge using the nonlinear static method presented here in conjunction with iterative capacity spectrum method specified in the EC8 guidelines will be evaluated

102- مقاله انگلیسی- COUPLED GURSON PLASTICITY AND DAMAGE MODEL FOR

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شماره فایل : 102

COUPLED GURSON PLASTICITY AND DAMAGE MODEL FOR CONCRETE STRUCTURES IN DYNAMICSAbstract

This study deals with the aspects of the concrete behaviour under dynamic loading such as impacts or explosions. For these kinds of sollicitations concrete experiences compaction (a decrease of porosity),plastic strains in compression and also cracking in tension. It is relevant to be able to represent, at the same time, the phenomena of compaction of material, as well as the rupture by extension. Recently,new dynamic experiments performed on con[1]ned concrete (to obtain compaction), made it possible to highlight a signi[1]cant effect of the strain rate on the spherical behaviour of concrete. Following these experimental observations, a viscoplastic and visco-damage model was developed. This model is based on Perzyna viscoplasticity associates with a modi[1]ed Gurson yield function and on a visco-damage model. This constitutive model for concrete is able to represent the rate effect experimentally observed. The model presented was implemented in the [1]nite element code LS-DYNA3D. Simulations of tests carried out on structures allowed to validate the numerical implementation, as well as the model for fast dynamic loading.

Keywords: dynamics, concrete, plasticity, damage

نقشه ارومیه فایل کد و پی دی اف

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شماره فایل : 149

 نشریه 164 سازمان مدیریت- دستورالعمل هدایت هیدرولیکی خاک به روش پیزومتری

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شماره فایل : ۱۴۳

 مقاله السیور- ANALYTICAL AND EXPERIMENTAL STUDIES ON BUCKLING RESTRAINE

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شماره فایل : 99

ANALYTICAL AND EXPERIMENTAL STUDIES ON BUCKLING RESTRAINED BRACED COMPOSITE FRAMES

SUMMARY

Analytical and experimental studies on the seismic behavior of buckling restrained braced frames(BRBFs) with concrete filled steel tubular (CFT) columns are being conducted at the ATLSSCenter, Lehigh University. The objectives of these studies are to investigate the seismicperformance of this type of frame, to evaluate existing design criteria, and to calibrate analytical models. The project is sponsored by the National Science Foundation in conjunction with the U.S.-Japan Cooperative Research Program on Composite and Hybrid Structures. A 4-story prototype building was designed with buckling restrained braced frames (BRBFs) as the lateral load resisting system. The columns in this frame are CFT members and the beams are structural steel sections. Design criteria were taken from the IBC 2000 and the AISC/SEAOC Recommended Design Provisions for BRBFs. A 1-bay prototype BRBF, representing one-quarter of the lateral load resisting system in one direction, was extracted from the prototype building for analysis. The analysis program DRAIN-2DX was used to model the prototype frame including material and geometric nonlinearities. The force-deformation relationship used in the buckling restrained brace model incorporates both isotropic and kinematic hardening. Nonlinear time history analyses were conducted using an ensemble of ground motions consisting of natural earthquake records and one artificial earthquake record. The earthquake records were scaled to two different seismic input levels: Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE). A statistical summary of the analysis results was developed at both seismic input levels. Performance objectives were defined and used to evaluate the analysis results. The life safety (LS) performance level was the target level for the DBE and the collapse prevention (CP) performance level was the target level for the MCE. Acceptable BRBF behavior was observed at both seismic input levels. A large-scale BRBF experimental investigation is planned. This paper presents the results of the analytical study and briefly summarizes the upcoming experimental program.

Keywords: Ductile design; Seismic force reduction; Hysteretic behaviour

مقاله السیور- application of the equvalent column method for fleural buc

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شماره فایل : 100

APPLICATION OF THE EQUIVALENT COLUMN METHOD FOR FLEXURAL BUCKLING ACCORDING TO THE NEW EC3-RULES

Abstract

The rules in EN 1993-1-1 provide an approach for the stability check of members and frames under axial compression and bending with the “equivalent column method”. This method is based on the use of the specific buckling length of the structure and of first order internal forces. In addition, a second approach is provided where individual members are considered like “cut-out members” of the system with end-moments including the second order sway effects. For the check of equivalent members or cut-out members the appropriate moment diagram to be used in the design formula has not been defined in the code yet. The present paper – after explaining the conceptual background of the methods – deals with the application on individual members with different boundary conditions as well as on frame systems of sway type. Comparisons of the results of the code-formulae with numerical calculations were made to illustrate the efficiency of the different methods.

KEYWORDS

Eurocode3-Part 1, flexural buckling, equivalent member, effective length method, amplified sway method, member buckling, frame analysis

98- مقاله السیور- Seismic performance of RC frames designed for three differ

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شماره فایل : 98

Seismic performance of RC frames designed for three different ductility levels

Abstract

The concept of “making structures ductile” has prevailed in modern earthquake-resistant building design. In this context, questions remain regarding the selection of adequate ductility levels and the corresponding seismic force reduction factor q for a specific class of structures, whereas the detailing requirements to ensure the desired ductility continue to be refined. In the current investigation, three simple frames were designed for different ductility levels according to EC8 [Eurocode 8: Design provisions for earthquake resistance of structures. CEN (European Commission for Standardisation)/TC250/SC8, 1994] and their actual performance when subjected to earthquake simulation tests are observed and compared. Results indicate that under the “ductility for seismic force reduction” trade-off scheme, the frame designed for high ductility (thus large q factor) tends to attract more extensive damage due to large yield excursion, resulting in certain performance reduction. Insufficient confinement could lead to degrade hysteretic behaviour in a rather sensitive manner. Satisfactory performance was observed in the frame designed for medium ductility where both the seismic force reduction factor and the overall ductility were in the order of 3–4. In general, the overall and local ductility demands and the q-factors were observed to correlate in a rather predictable manner.

Keywords: Ductile design; Seismic force reduction; Hysteretic behaviour

مقاله السیور- Refined force reduction factors for seismic design

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شماره فایل :97

Refined force reduction factors for seismic design

Abstract

Whereas seismic design based on deformations is a concept that is gaining ground, existing codes are fundamentally force-based, with a final check on deformations. A central feature of force-based seismic design is the response modification factor (R or q).Many studies have attempted to quantify the potential of structural systems to delimit the level of force imposed by virtue of their ductility and energy absorption capacity. This paper employs a well controlled and evenly distributed earthquake data-set (in magnitude, distance and site characterization spaces) to derive values for force reduction factors needed for the structure to reach, and not exceed, a pre-determined level of ductility. It is observed that the force modification factors are only slightly influenced by the shape of the hysteretic model used in their derivation and even less sensitive to strong motion characteristics. A linear representation is recommended for use in a benchmark for ‘demand’ considerations and given in an easy-to-use parametric form.

Keywords: Force reduction factors; Seismic design; Ductility; Design spectrum

مقاله السیور- Probabilistic evaluation of behaviour factors in EC8-d

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شماره فایل : 96

Probabilistic evaluation of behaviour factors in EC8-designed R/C Frames

A methodology for the probabilistic assessment of reinforced concrete (R/C) frames which takes into account material variability,confinement model uncertainty and the uncertainty in local and global failure criteria is applied for the derivation of vulnerabilitycurves for the serviceability and ultimate limit states of a multi-storey frame designed to Eurocode 8. By combining the uncertaintiesaffecting structural vulnerability and seismic hazard, the seismic reliability is quantified in terms of the probability of failure forany given design life period. It is found that, while adequate safety margins exist for the ULS, the reliability against the SLS strongly depends on the structural criterion adopted for the definition of this state. The variability in the actual behaviour factor of this frame is also estimated, and the appropriateness of the EC8 specified value is assessed

Keywords: Probabilistic methods; Seismic design; R/C frames; Behaviour factors; Eurocodes