The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform

Masoud Ghorbani - One of the best experts on this subject based on the ideXlab platform.

  • partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations
    International journal of mining science and technology, 2019
    Co-Authors: Raheleh Masoudi, Mostafa Sharifzadeh, Masoud Ghorbani
    Abstract:

    Abstract Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early Stiff Behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The Behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.

  • Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations
    Elsevier, 2019
    Co-Authors: Reza Masoudi, Mostafa Sharifzadeh, Masoud Ghorbani
    Abstract:

    Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early Stiff Behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The Behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones. Keywords: Rockbolt, Tunnel support, Collar bonding, Seismic rock support, Tunnellin

Markus J Buehler - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear material Behaviour of spider silk yields robust webs
    Nature, 2012
    Co-Authors: Steven W Cranford, Anna Tarakanova, Nicola Pugno, Markus J Buehler
    Abstract:

    Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence to the geometry of a web. This material system, highly adapted to meet a spider's many needs, has superior mechanical properties. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres, and into the mechanical characteristics of web-like structures, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress--involving softening at a yield point and substantial Stiffening at large strain until failure--as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic-plastic (softening) material Behaviour. We also show that under distributed loads, such as those exerted by wind, the Stiff Behaviour of silk under small deformation, before the yield point, is essential in maintaining the web's structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

  • nonlinear material Behaviour of spider silk yields robust webs
    Nature, 2012
    Co-Authors: Steven W Cranford, Anna Tarakanova, Nicola Pugno, Markus J Buehler
    Abstract:

    Spider web deformation simulations, theory and experiments reveal how the nonlinear response of spider silk to strain and the discrete geometry of a web contribute to its robustness, integrity and performance. Spider silk is one of nature's 'super-materials'. Its remarkable mechanical properties include high extensibility and strength comparable to that of steel. But Markus Buehler and colleagues show that it is not just these virtues that make silk ideal for web construction. Silk's nonlinear stress response — linear at low strain, suddenly softening as strain increases then Stiffening prior to failure — is also critical. This Behaviour allows webs to keep their shape when experiencing small, distributed loads such as those exerted by wind. But during strong local deformations, such as those caused by falling debris, the geometrical arrangement of the threads and the nonlinear stress response combine to limit damage to the area near the impact site, so that the web remains functional. Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre1,2,3,4,5. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence6 to the geometry of a web7. This material system8, highly adapted to meet a spider’s many needs, has superior mechanical properties9,10,11,12,13,14,15. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres1,6,10,13,16,17, and into the mechanical characteristics of web-like structures18,19,20,21, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress—involving softening at a yield point and substantial Stiffening at large strain until failure—as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic–plastic (softening) material Behaviour. We also show that under distributed loads, such as those exerted by wind, the Stiff Behaviour of silk under small deformation, before the yield point, is essential in maintaining the web’s structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

Anna Tarakanova - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear material Behaviour of spider silk yields robust webs
    Nature, 2012
    Co-Authors: Steven W Cranford, Anna Tarakanova, Nicola Pugno, Markus J Buehler
    Abstract:

    Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence to the geometry of a web. This material system, highly adapted to meet a spider's many needs, has superior mechanical properties. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres, and into the mechanical characteristics of web-like structures, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress--involving softening at a yield point and substantial Stiffening at large strain until failure--as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic-plastic (softening) material Behaviour. We also show that under distributed loads, such as those exerted by wind, the Stiff Behaviour of silk under small deformation, before the yield point, is essential in maintaining the web's structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

  • nonlinear material Behaviour of spider silk yields robust webs
    Nature, 2012
    Co-Authors: Steven W Cranford, Anna Tarakanova, Nicola Pugno, Markus J Buehler
    Abstract:

    Spider web deformation simulations, theory and experiments reveal how the nonlinear response of spider silk to strain and the discrete geometry of a web contribute to its robustness, integrity and performance. Spider silk is one of nature's 'super-materials'. Its remarkable mechanical properties include high extensibility and strength comparable to that of steel. But Markus Buehler and colleagues show that it is not just these virtues that make silk ideal for web construction. Silk's nonlinear stress response — linear at low strain, suddenly softening as strain increases then Stiffening prior to failure — is also critical. This Behaviour allows webs to keep their shape when experiencing small, distributed loads such as those exerted by wind. But during strong local deformations, such as those caused by falling debris, the geometrical arrangement of the threads and the nonlinear stress response combine to limit damage to the area near the impact site, so that the web remains functional. Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre1,2,3,4,5. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence6 to the geometry of a web7. This material system8, highly adapted to meet a spider’s many needs, has superior mechanical properties9,10,11,12,13,14,15. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres1,6,10,13,16,17, and into the mechanical characteristics of web-like structures18,19,20,21, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress—involving softening at a yield point and substantial Stiffening at large strain until failure—as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic–plastic (softening) material Behaviour. We also show that under distributed loads, such as those exerted by wind, the Stiff Behaviour of silk under small deformation, before the yield point, is essential in maintaining the web’s structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

Raheleh Masoudi - One of the best experts on this subject based on the ideXlab platform.

  • partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations
    International journal of mining science and technology, 2019
    Co-Authors: Raheleh Masoudi, Mostafa Sharifzadeh, Masoud Ghorbani
    Abstract:

    Abstract Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early Stiff Behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The Behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.

Mostafa Sharifzadeh - One of the best experts on this subject based on the ideXlab platform.

  • partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations
    International journal of mining science and technology, 2019
    Co-Authors: Raheleh Masoudi, Mostafa Sharifzadeh, Masoud Ghorbani
    Abstract:

    Abstract Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early Stiff Behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The Behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.

  • Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations
    Elsevier, 2019
    Co-Authors: Reza Masoudi, Mostafa Sharifzadeh, Masoud Ghorbani
    Abstract:

    Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early Stiff Behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The Behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones. Keywords: Rockbolt, Tunnel support, Collar bonding, Seismic rock support, Tunnellin