Publications de Elyas Ghafoori

Evaluation of Interface and Residual Strain of NiTi Layer Deposited on NiTiX Substrate by Laser Powder Bed Fusion

Elyas Ghafoori, Christian Leinenbach, Irene Ferretto, Mahbod Golrang, Mahshid Memarian

This study investigates the microstructure and properties of functionally graded NiTi alloy bilayers. The NiTi layer is printed by laser powder bed fusion on a NiTiX (where X is Hf or Cu) substrate prepared by vacuum arc remelting. Specimens produced with ...

Wiley-V C H Verlag Gmbh2024

Experimental behavior of iron-based shape memory alloys under cyclic loading histories

Elyas Ghafoori, Albano António De Abreu E Presa De Castro E Sousa, Diego Isidoro Heredia Rosa, Masoud Motavalli, Dimitrios Lignos, Alexander Riley Hartloper

The present paper investigates the behavior of iron-based shape memory alloys (Fe-SMAs) subjected to cyclic inelastic straining by means of uniaxial coupon experiments. The tests feature round bar coupons subjected to a broad range of uniaxial cyclic strai ...

2021

FE analysis and experimental validation of mechanical wedge-barrel anchors for CFRP rods

Alain Nussbaumer, Elyas Ghafoori, Hossein Heydarinouri

This paper presents a comparative study of the geometrical optimization of mechanical wedge-barrel anchors for prestressed carbon fiber-reinforced polymer (CFRP) rods. Various anchor configurations were simulated using three-dimensional finite-element (FE) ...

ELSEVIER SCI LTD2021

Strengthening of Steel Connections in a 92-Year-Old Railway Bridge Using Prestressed CFRP Rods: Multiaxial Fatigue Design Criterion

Alain Nussbaumer, Elyas Ghafoori, Masoud Motavalli, Hossein Heydarinouri

This paper presented a new retrofit system for strengthening the stringer-to-floor-beam double-angle connections in a 92-year-old riveted railway bridge in Switzerland, using prestressed carbon fiber-reinforced polymer (CFRP) rods. The strengthening system ...

ASCE-AMER SOC CIVIL ENGINEERS2021

Development of a Mechanical Wedge-Barrel Anchor for CFRP Rods: Static and Fatigue Behaviors

Alain Nussbaumer, Elyas Ghafoori, Masoud Motavalli, Hossein Heydarinouri

In this study, a mechanical anchorage for prestressed carbon fiber-reinforced polymer (CFRP) rods was proposed. The proposed anchorage consisted of a steel barrel with a conical hole and three separate aluminum wedges that are in direct contact with the CF ...

ASCE-AMER SOC CIVIL ENGINEERS2021

Multiaxial fatigue criteria for prestressed strengthening of steel connections

Alain Nussbaumer, Elyas Ghafoori, Masoud Motavalli, Hossein Heydarinouri

In this study, the high-cycle fatigue behavior of bridge connections subjected to distortion-induced loadings (generating multiaxial stresses) and strengthened with prestressed elements were experimentally investigated. Thereafter, appropriate critical pla ...

ELSEVIER SCI LTD2021

Development of Mechanical Strengthening System for Bridge Connections Using Prestressed CFRP Rods

Alain Nussbaumer, Elyas Ghafoori, Masoud Motavalli, Hossein Heydarinouri

Stringer-to-floor beam web-to-web double-angle connections are among the most fatigue-prone elements in old riveted bridges. These connections are often designed to carry only shear loads. However, in these elements, fatigue damage occurs because of the ou ...

ASCE-AMER SOC CIVIL ENGINEERS2021

Behavior of prestressed CFRP plates bonded to steel substrate: Numerical modeling and experimental validation

Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

In recent years, retrofitting of steel structures has emerged as a major issue in structural engineering and construction management. As the adhesive bond is often the critical aspect controlling the actual performance of steel profiles externally strength ...

ELSEVIER SCI LTD2019

Proposed criterion for fatigue strengthening of riveted bridge girders

Alain Nussbaumer, Elyas Ghafoori, Hossein Heydarinouri

Elsevier2019

An experimental investigation into bond behavior of prestressed CFRP to steel substrate

Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

Nowadays, strengthening of existing steel structures using advanced carbon fiber reinforced polymer (CFRP) composites is becoming a common technique due to the unique advantages of the material such as light weight, high strength and fatigue endurance, as ...

2017

A novel mechanical clamp for strengthening of steel members using prestressed CFRP plates

Alain Nussbaumer, Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

Strengthening of existing steel members using prestressed carbon fiber reinforced polymer (CFRP) plates has certain advantages over non-prestressed reinforcement, especially due to the reduction in permanent tensile stresses acting on the steel members. Ho ...

2017

Fatigue strengthening of cracked steel plates using prestressed unbonded CFRP reinforcements

Alain Nussbaumer, Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

Fatigue strengthening of existing steel structures is of great importance and has attracted lots of interest recently. Apart from the conventional strengthening technique, i.e. utilizing bulky and heavy steel plates and its disadvantages, carbon fiber rein ...

2017

Feasibility of iron-based shape memory alloy strips for prestressed strengthening of steel plates

Elyas Ghafoori, Moslem Shahverdi, Ardalan Hosseini, Masoud Motavalli

Iron-based shape memory alloys (Fe-SMAs) are advanced materials that can be used as prestressing elements for strengthening and rehabilitation of civil structures. In this paper, the results of a feasibility study on the application of shape memory effect ...

2017

Recent developments of strengthening techniques for metallic structures

Elyas Ghafoori, Ardalan Hosseini

This paper introduces the most recent techniques that have been developed for pre-stressed strengthening of metallic members. Details of utilization of new advanced materials such as carbon-fibre reinforced polymer (CFRP), NiTiNb- and Fe-shape memory alloy ...

2017

Development of anchorage systems for strengthening of steel plates with iron-based shape memory alloy strips

Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

The aim of this study is to propose a series of mechanical anchorage system for strengthening of steel plates with iron-based shape memory (Fe-SMA) strips. Four different friction-based mechanical clamps to anchor the Fe-SMA strips to the steel substrate w ...

2017

Stress Analysis of Unbonded and Bonded Prestressed CFRP-strengthened Steel Plates

Alain Nussbaumer, Elyas Ghafoori, Ardalan Hosseini, Masoud Motavalli

Numerous research studies are available in the literature on strengthening of steel members using carbon fiber reinforced polymer (CFRP) composites. Although it is clear that strengthening using prestressed CFRP plates has several advantages over non-prest ...

The Hong Kong Polytechnic University2016

Fatigue strengthening of riveted girders in a historic railway metallic bridge in Switzerland using pre-stressed un-bonded CFRP laminates

Andrin Herwig, Alain Nussbaumer, Mario Fontana, Elyas Ghafoori, Gary Scott Prinz, Masoud Motavalli

CRC Press2016

Fatigue design criteria for strengthening metallic beams with bonded CFRP plates

Alain Nussbaumer, Mario Fontana, Elyas Ghafoori, Masoud Motavalli

Different failure criteria used to prevent fatigue crack initiation in metallic members are described. A series of closed-form analytical solutions were developed to predict the fatigue resistance of metallic beams after strengthening with carbon fiber-rei ...

Elsevier2015

Determination of minimum CFRP pre-stress levels for fatigue crack prevention in retrofitted metallic beams

Andrin Herwig, Alain Nussbaumer, Elyas Ghafoori, Gary Scott Prinz

The majority of fatigue strengthening studies focus on reducing propagation rates of existing cracks, ignoring the crack initiation stage. Many existing metallic bridge members however do not contain existing cracks, but rather are nearing their design fat ...

Elsevier2015

Finite element modeling for fatigue strengthening of metallic riveted bridges using un-bonded pre-stressed CFRP plates

Andrin Herwig, Alain Nussbaumer, Mario Fontana, Elyas Ghafoori, Gary Scott Prinz

Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures and as such structural modifications that affect ...

2013