- Đã tạo: 22-11-21
- Lần Cuối Đăng Nhập: 22-11-21
Thông Tin Người Dùng
drymoisture
Structural behavior of precast concrete wall panels due to dynamic load: A review
The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of cement wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.
Architectural precast concrete wall panels that act as loadbearing elements in a building are both a structurally efficient and economical means o f transferring floor and roof loads through the structure and into the foundation. In many cases, this integration can also simplify construction and reduce costs. This article presents the many benefit s that ca n be derived from using loadbearing architectural precast concrete walls in buildings. Discussed herein are the various shapes and sizes of wall pane ls, major design considerations, and when loadbearing or shear wall units should be the first design choice. The role o f connections, shear walls, and the use of precast concrete as forms for cast-in-place concrete is explained. In general, the design methods and techniques presented in this article apply to buildings in both seismic and non-seismic areas. The latter part of this article shows how these design principles can be applied in practice in a variety of buildings. These examples illustrate the use of window wall panels, spandrels, and solid or sandwich wall panels as the loadbearing wall members. When all the advantages of using architectural precast concrete as loadbearing walls are added up, it makes good sense to use this structural form in building applications.
An experimental study has been carried out to determine the strength and behaviour of bamboo-reinforced concrete wood texture cement wall panel under one-way in-plane action. Three full-scale bamboo-reinforced concrete wall panels were tested to fail under a uniformly distributed load applied at an eccentricity of t/6. Slenderness ratio of all wall panels was kept constant as 25 with varying aspect ratio and thinness ratio. The influence of aspect ratio and thinness ratio on the ultimate strength and behaviour of wall panel was studied. The aspect ratio of wall panels considered includes 1, 1.204 and 1.515, and thinness ratio of wall panels includes 16.5, 20.75 and 25. Based on the study, an empirical equation for predicting the ultimate load of bamboo-reinforced concrete wall panel was proposed.
The effect of the earthquake resulted in the destruction of infrastructure, especially residential buildings. The construction of decent housing with an adequate level of security is a demand. Generally, the most severe damage when an earthquake occurs is wall collapse of the houses. The precast panel wall is an alternative solution in answering the needs of post-earthquake housing development, because of the fast construction time and high calculation accuracy. The behavior of structural precast concrete split rock surface wall panels designed improperly instead of following the standard or regulations will likely encounter a poor performance during an earthquake compared to those designed in accordance with the standards. The purpose of the present study is to compile the findings from previous studies of precast concrete panel walls, especially their performances in handling earthquake load. It reveals that the stability, especially in ductility, affects the performance of precast concrete panel walls. In this study, the walls of precast concrete panels are made in half scale and given dynamic loads to simulate earthquake forces. This review is expected to provide guideline of similar subsequent research.
It’s no wonder demand for precast is rising, especially considering the numerous benefits structural precast panels offer — from quick installation to fire resistance.
1. Thermal insulation
All elements of a well-engineered structural precast panel work together to provide a high level of insulation. Manufacturers often use a combination of concrete and EPS foam that maximizes the foam in the concrete piece, increasing insulation capabilities. A building constructed of structural precast panels may reduce energy consumption by as much as 30%.
2. Sustainable materials
Quite simply, a building made with structural precast panels will consume less energy, but an idea that should be at the heart of any sustainability conversation is product life. The use of concrete dates back to Roman times and its durability is still on display all across Europe. That raw, ancient building material has remained virtually unchanged for thousands of years. Many of the materials used in precast concrete are, as a rule, locally sourced, including the cement, the coarse and fine aggregates, and the steel.
3. Long-term viability and flexibility
Structural precast allows for a very modular building envelope. As business requirements change and needs evolve, an existing precast building has the flexibility to be expanded and modified. With structural precast concrete panels, you can add or remove pedestrian doors and dock doors, incorporate daylighting options, and even remove 75% of a wall. And due to its modular design, total repurposing of a precast building is entirely possible; churches can become car dealerships, warehouses can become micro-breweries… the options are only limited by a property owner’s imagination.
4. Quick installation
Speed is a critical hallmark of structural precast construction. “With precast panels, you can establish a larger completed footprint in a shorter amount of time,” says George Miks, director of engineering.“If you think of a masonry wall, what they send out to the site are a bunch of blocks that have to be assembled and constructed out in the field.” When structural precast panels arrive at a job site, the pieces are ready to install. If things go smoothly out in the field, an experienced crew can install 20 to 30, 12-foot panels in a day.
5. Load-bearing capabilities and wind resistance
Structural precast concrete panels are comprised of high-strength concrete and prestressed steel strand. It’s relatively routine for precast concrete wall panels have a compressive strength of approximately 7,000 PSI. You can apply loads in excess of 100,000 pounds to the panels, Miks says. “When you build steel buildings, for instance, you have to put up perimeter beams and columns and then put steel skin against it. All of that steel has to support those enclosure panels,” Miks says. “With a structural precast wall system, you don’t need any of those perimeter beams and columns. You can just tip up the panel and have the roof steel members themselves attach to the precast. That also means you’ll be spending less on steel.” Precast also stands up to Mother Nature’s wrath, shrugging off tornadoes, flying projectiles and winds up to 250 miles per hour.
6. Fire and sound ratings
Concrete is obviously an effective barrier for fire; it simply doesn’t burn well. Precast concrete thin cement rammed earth wall panels are capable of providing a two- to four-hour fire rating. Precast walls also stay intact even in hot chemical fires. Warehouses often use precast wall panels as dividers to protect goods on the other side of fire-prone areas. “The more delay you can create from one side to the other, the better chance of getting people out safely without incident and also the higher probability of protecting goods and services,” Miks says.
Constructing a commercial structure is a huge undertaking and a significant investment. Whether you’re charged with the growth of a company, serving your community or building a legacy of your own, precast construction is a solid, responsible option said Miks.
In this paper, an optimization-based design model of precast concrete cement rustic decoration wall panels for a building facade is presented. The key concept is an integrated model that can concurrently handle all of the related design and construction disciplines in the decision making process. The integrated model is decomposed hierarchically into several subproblems, thus a multilevel multiobjective optimization problem is obtained. Besides the multilevel aspect, the model presented can also handle knowledge-based requirements which are in general difficult to deal with by conventional hill-climbing optimization schemes. A solution procedure to solve this model is developed and applied to an example of PCWP for a four-story building facade.
The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of cement wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.
Architectural precast concrete wall panels that act as loadbearing elements in a building are both a structurally efficient and economical means o f transferring floor and roof loads through the structure and into the foundation. In many cases, this integration can also simplify construction and reduce costs. This article presents the many benefit s that ca n be derived from using loadbearing architectural precast concrete walls in buildings. Discussed herein are the various shapes and sizes of wall pane ls, major design considerations, and when loadbearing or shear wall units should be the first design choice. The role o f connections, shear walls, and the use of precast concrete as forms for cast-in-place concrete is explained. In general, the design methods and techniques presented in this article apply to buildings in both seismic and non-seismic areas. The latter part of this article shows how these design principles can be applied in practice in a variety of buildings. These examples illustrate the use of window wall panels, spandrels, and solid or sandwich wall panels as the loadbearing wall members. When all the advantages of using architectural precast concrete as loadbearing walls are added up, it makes good sense to use this structural form in building applications.
An experimental study has been carried out to determine the strength and behaviour of bamboo-reinforced concrete wood texture cement wall panel under one-way in-plane action. Three full-scale bamboo-reinforced concrete wall panels were tested to fail under a uniformly distributed load applied at an eccentricity of t/6. Slenderness ratio of all wall panels was kept constant as 25 with varying aspect ratio and thinness ratio. The influence of aspect ratio and thinness ratio on the ultimate strength and behaviour of wall panel was studied. The aspect ratio of wall panels considered includes 1, 1.204 and 1.515, and thinness ratio of wall panels includes 16.5, 20.75 and 25. Based on the study, an empirical equation for predicting the ultimate load of bamboo-reinforced concrete wall panel was proposed.
The effect of the earthquake resulted in the destruction of infrastructure, especially residential buildings. The construction of decent housing with an adequate level of security is a demand. Generally, the most severe damage when an earthquake occurs is wall collapse of the houses. The precast panel wall is an alternative solution in answering the needs of post-earthquake housing development, because of the fast construction time and high calculation accuracy. The behavior of structural precast concrete split rock surface wall panels designed improperly instead of following the standard or regulations will likely encounter a poor performance during an earthquake compared to those designed in accordance with the standards. The purpose of the present study is to compile the findings from previous studies of precast concrete panel walls, especially their performances in handling earthquake load. It reveals that the stability, especially in ductility, affects the performance of precast concrete panel walls. In this study, the walls of precast concrete panels are made in half scale and given dynamic loads to simulate earthquake forces. This review is expected to provide guideline of similar subsequent research.
It’s no wonder demand for precast is rising, especially considering the numerous benefits structural precast panels offer — from quick installation to fire resistance.
1. Thermal insulation
All elements of a well-engineered structural precast panel work together to provide a high level of insulation. Manufacturers often use a combination of concrete and EPS foam that maximizes the foam in the concrete piece, increasing insulation capabilities. A building constructed of structural precast panels may reduce energy consumption by as much as 30%.
2. Sustainable materials
Quite simply, a building made with structural precast panels will consume less energy, but an idea that should be at the heart of any sustainability conversation is product life. The use of concrete dates back to Roman times and its durability is still on display all across Europe. That raw, ancient building material has remained virtually unchanged for thousands of years. Many of the materials used in precast concrete are, as a rule, locally sourced, including the cement, the coarse and fine aggregates, and the steel.
3. Long-term viability and flexibility
Structural precast allows for a very modular building envelope. As business requirements change and needs evolve, an existing precast building has the flexibility to be expanded and modified. With structural precast concrete panels, you can add or remove pedestrian doors and dock doors, incorporate daylighting options, and even remove 75% of a wall. And due to its modular design, total repurposing of a precast building is entirely possible; churches can become car dealerships, warehouses can become micro-breweries… the options are only limited by a property owner’s imagination.
4. Quick installation
Speed is a critical hallmark of structural precast construction. “With precast panels, you can establish a larger completed footprint in a shorter amount of time,” says George Miks, director of engineering.“If you think of a masonry wall, what they send out to the site are a bunch of blocks that have to be assembled and constructed out in the field.” When structural precast panels arrive at a job site, the pieces are ready to install. If things go smoothly out in the field, an experienced crew can install 20 to 30, 12-foot panels in a day.
5. Load-bearing capabilities and wind resistance
Structural precast concrete panels are comprised of high-strength concrete and prestressed steel strand. It’s relatively routine for precast concrete wall panels have a compressive strength of approximately 7,000 PSI. You can apply loads in excess of 100,000 pounds to the panels, Miks says. “When you build steel buildings, for instance, you have to put up perimeter beams and columns and then put steel skin against it. All of that steel has to support those enclosure panels,” Miks says. “With a structural precast wall system, you don’t need any of those perimeter beams and columns. You can just tip up the panel and have the roof steel members themselves attach to the precast. That also means you’ll be spending less on steel.” Precast also stands up to Mother Nature’s wrath, shrugging off tornadoes, flying projectiles and winds up to 250 miles per hour.
6. Fire and sound ratings
Concrete is obviously an effective barrier for fire; it simply doesn’t burn well. Precast concrete thin cement rammed earth wall panels are capable of providing a two- to four-hour fire rating. Precast walls also stay intact even in hot chemical fires. Warehouses often use precast wall panels as dividers to protect goods on the other side of fire-prone areas. “The more delay you can create from one side to the other, the better chance of getting people out safely without incident and also the higher probability of protecting goods and services,” Miks says.
Constructing a commercial structure is a huge undertaking and a significant investment. Whether you’re charged with the growth of a company, serving your community or building a legacy of your own, precast construction is a solid, responsible option said Miks.
In this paper, an optimization-based design model of precast concrete cement rustic decoration wall panels for a building facade is presented. The key concept is an integrated model that can concurrently handle all of the related design and construction disciplines in the decision making process. The integrated model is decomposed hierarchically into several subproblems, thus a multilevel multiobjective optimization problem is obtained. Besides the multilevel aspect, the model presented can also handle knowledge-based requirements which are in general difficult to deal with by conventional hill-climbing optimization schemes. A solution procedure to solve this model is developed and applied to an example of PCWP for a four-story building facade.
