Slab-on-Grade or floating slab as known in other resources is an easy example of the shallow foundation. Despite its easy look and it has many critical points concerning the thickness and the design. As a definition it is a flat structural element that is poured and constructed to transfer the loads directly to the ground. The formworks of the slab are easy to be used because it covers large areas with almost constant thickness. It is known as a cheap and fast foundation.
It proved a strong resistance under dynamic loads as well as the static ones. It is used in the one story constructions and it holds moving loads and one story walls.
As shown in the image below, The Slab-on-Grade depends on the subgrade underneath, the strength and the stability of the subgrade is very important key for the strong and stable Slab. Designers usually care for improving the underneath the Slab. The modulus of subgrade reaction is the conventional notation for the strength of the subgrade. It is also the key note in the design process for the Slab-on-Grade.
The concrete industries progress showed that the concrete Slab-on-Grade can be modified to be stiffer and have a higher tensile strength. It may resist the changes in soil due to swelling for example.
As we have mentioned before Slab-on-Grade is strong under the dynamic loads so it is widely used in airports, industrial facilities and garages. It resists the loads from the tires of airplanes, forklifts and moving vehicles. Also it is used for the one or two stories residential and commercial buildings that don’t use the basements and the facilities under the level of the slab. California and Texas have many successful stories for houses built on Slabs-on-Grade. The Elevated tanks show a good prac...
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...nd Calderwood 1978; Suaris and Shah 1984), because it requires higher energy to split the fibers from the concrete.
The flexural strength usually reported by the time the first crack appears which is corresponding to the point where the load-deformation curve moves out of linearity (Point A on Figure 4). The second value is the failure value or in other words it is called the ultimate flexural strength or the modulus of rupture (Point C on Figure 4). Johnston reported that the prismatic fibers and hooked ones have effects on the strength of the unreinforced matrices by about 100 percent. High strengths can be achieved in mortars with w/c ratio of 0.45 to 0.55. Using 1.5% of volume as fibers may increase the strength value to the range of (6.5 to 10 MPa) and Johnston experiments in 1980 showed that using 2.5% of volume as fibers may increase the strength to 13 MPa.
To test the load handling capabilities of the structure, two separate loads were applied independently. First, a standard brick with the dimensions of 3-5/8” x 2-1/4” x 8” and an approximate weight of 4.5 pounds was place on top of the structure to observe the effects. The structure was able to support this distributed load with ease, causing no visible bending, breaking, or failures. The brick was then removed before performing the second test. To perform the second test, the structure was suspended across two tables, with a string attached to the center of one side of the truss systems. The standard brick was then attached to the rope to create a vertical load. After carefully attaching the brick to the string, the structure began to bend before eventually failing, causing the structure to break in
Modulus of elasticity is defined as the comparative stiffness of a material. A stiffer material will have a higher elastic modulus. Fracture toughness is the amount of stress required to propagate a preexisting flaw. It describes resistance of a material with a pre-existing flaw to fail. These two properties will be evaluated for resin composites in our paper through journal articles.
Part A: Structural Safety Part B: Fire Safety Part C: Resistance to contaminants and moisture
In this chapter, the structural plan is taken and it is designed in the sap2000 software by taking the center line diagram and firstly a basic ground level is designed and then the required no of levels is placed according to their different levels of height. The analysis is being checked by firstly placing the beams and coloums to be placed correctly at their position and checked for safety i.e., the slab does not fail and
Reinforced concrete is stronger than basic concrete. Steel reinforcing bars known as rebar is incorporated in the concrete structure to act together in resisting the force. The steel reinforcing bars absorbs tensile and compression because plain conc...
For its realization, it was required to construct two cantilever thick concrete sections hanging from each abutment. In this case, two deficiencies with regard to reinforcement design were identified: improper detailing of rebars and absence of shear reinforcement in the middle of the concrete section, the later though was not required by the code of practice at that time. Therefore, improper detailing that caused the concentration of numerous bars in the same plane created a plane of weakness, which any cracks developing from it couldn’t be intercepted due to the absence of any shear reinforcement bars in the middle of the concrete slab. As a result, the bridge lost its ductility and was destined to a sudden crushing failure that prohibited any precautionary measures. (Johnson G. ,
8 4.4- PAVEMENT SURFACES: ........................................................... 9 4.5- DRAINAGE FOR NEW DEVELOPMENTS: ................................... 10 5- CONCLUSION: .......................................................................... 11 6- REFERENCES: ........................................................................... 13 1 INTRODUCTION:
Bored piles construction is done using the suitable rotary drills depending on the diameter, depth, condition of the soil and construction method. Usually bore-holes are stabilized with a temporary or permanent casing. The common material used for the casing is steel and it is also normal called as steel casing. The length of the steel casing is also determined from the soil conditions that are discovered at the actual site.
Because Yuhu is located in an earthquake zone, the capability to resist earthquake is highly concerned for the local buildings. In tradition houses, the main structure is hold by wood frames and stones are mounted on the exterior. During the 1996 level 7 earthquake, most of the exterior stone walls were collapsed but wood frame structures well remained. In the design of this project, Li adopted this traditional structure system and added new technologies to improve its resistance to earthquake. In traditional house construction, stones are mounted to the exterior walls and are likely to collapse during earthquake. In this project, vertical steel bars are inserted in the stone walls at a set interval. Horizontal meshes are also installed in layers to prevent lateral force during frequent earthquakes. Traditional stone wall con...
The rigid characteristic of the pavement are associated with rigidity or flexural strength or slab action so the load is distributed over a wide area of subgrade soil. Rigid pavement is laid in slabs with steel reinforcement. The rigid pavements are made of cement concrete either plan, reinforced or prestressed concrete. Critical condition of stress in the rigid pavement is the maximum flexural stress occurring in the slab due to wheel load and the temperature changes. Rigid pavement is designed and analyzed by using the elastic theory.A typical sketch of rigid pavement is given in Figure 1.3.
The continuous strain, which the concrete undergoes due to application of external loads is called……………………………………….
Load bearing walls are those exposed to the external environment on at least one side.
As the effects of moving ground motions, the building structure starts to vibrate and induce inertia forces on them. Therefore, the structure of that zone needs to be suitably designed and provide specific details to stability and safety. A building failure can occur when the building has no strong joint components like walls, roofs, beam or column. As a consequence, the building move independently with their own directions and movements thus, it can result in separation of a building. The building also need to consider about the stiffness and stability.
Benefits of utilizing an EPS-block geofoam embankment include: (1) ease and speed of construction, (2) placement in adverse weather conditions, (3) possible elimination of the need for preloading, surcharging, and staged construction, (4) decreased maintenance costs as a result of less settlement from the low density of EPS-block geofoam, (6) reduction of lateral stress on bridge approach abutments, (7) use over existing utilities which reduces or eliminates utility relocation, (8) excellent durability, and (9) ability to be recycled. In a soil removal and replacement situation without the use of surcharging, the use of EPS-block geofoam may result in cost savings compared to other types of lightweight fill materials and conventional fill materials because the density of geofoam is 1/10th to 1/30th of the density of foamed concrete, 1/55th to 1/145th of the in-place density of boiler slag, and 1/100th of the density of conventional granular fill
A compliant tower is a flexible structure with flex plies (principally flexible legs or axial tubes) to control mass and stiffness characteristics so as to mitigate the effects of periodic wind, wave and current forces. The tower is supported laterally at its lower end by the flex piles, but is permitted to slide vertically along the flex piles and rotate about its lower end. In response to movement of the tower away from the vertical, the piles establish a righting moment (couple) acting at the point of pile attachment. This provides the stabilization necessary to restore the tower to a vertical orientation. Natural periods are usually greater than 25 sec so they are generally well outside wave periods. Compliant towers are designed to sustain significant lateral deflections and forces. Compliant tower are relatively slender compared to jacket/tower structure but have higher installation costs due to the portion of the flex pile must be driven after the tower in place and use a considerable amount of steel.