Written by Bradley Mackenzie
- Eccentric Foundations. An eccentric foundation is a foundation whereby t he wall sits on the outer edge of the foundation. ...
- Typical Foundations
- A typical foundation differs from this. This type of foundation can either be placed astride the line of junction, thereby acting as a Party Wall.
What is an eccentric foundation design?
An eccentric foundation is a foundation whereby the wall sits on the outer edge of the foundation. One may also ask, what are the minimum steps required for designing of a foundation?
What is the effect of eccentricity on analysis and design of isolated footings?
Effect Of Eccentricity On Analysis and Design Of Isolated Footings. Footings are often subjected to moments from columns in addition to the axial loads. The presence of certain amount of eccentricity of loading in the footing induces moment on footing.
What is an example of an eccentricity?
Eccentricity. The degree to which two forms fail to share a common center; for example, in a pipe or tube whose inside is off-center toth regard to the outside. In hollow extrusions: the difference between the maximum and minimum wall thickness at any single cross-section. Can you build on edge of foundation?
How to reduce the effects of eccentricity of columns?
- To reduce the effects of eccentricity, use foundation of columns with off- center loading. Geotechnical Engineering SNU Geotechnical Engineering Lab. 22 6) Effect of Layering
What is foundation eccentricity?
The eccentric footing is a spread or wall footing that must resist a moment in addition to the axial column load, and it has the shape of the shoe.
What is eccentricity footing?
Footings that are not concentrically loaded are known as “Eccentric Footings”. In addition, when footings are subjected to an axial load “P” and bending moment “M” or lateral force “H”, the footing will experience unbalanced stress distributions along the base of the footing.
What is eccentrically loaded foundation?
Normal footing becomes eccentrically load footing when there is an eccentricity in the loading or when there is a bending moment at the connection of footing and the column. The eccentricity could be in one direction or in both directions. Desing of the eccentrically loaded footing shall be done accordingly.
What is eccentric construction?
Architecture (Eccentric Construction) (Architektur (Excentrische Konstruktion)) Architecture (Eccentric Construction) and Architecture 1 (Construction on a Blue Ground) are two of the earliest instances in which László Moholy-Nagy used metallic paint, exemplifying his affinity for industrial finishes.
What is eccentricity in civil engineering?
The degree to which two forms fail to share a common center; for example, in a pipe or tube whose inside is off-center toth regard to the outside.
What is eccentric column?
When the load acting on the column is offset from the centroid of the column, then it establishes the bending of column along with the axial stress. This offset loading of the column is referred as eccentric loading.
What is concentric loading and eccentric loading?
Loads applied to the center of gravity of the column cross-section are considered concentric. A beam that passes over and rests on the top of a column is an example of concentric loading. COLUMN LOADING – ECCENTRIC LOADING. Any load which is not concentric is eccentric.
How do you calculate eccentric footing?
Volume of Concrete = Area x Depth. = L x B x D. = 0.6 x 0.50 x 0.55. = 0.165 m3Shuttering Area = Peripheral Length x Depth. = (L + B ) x 2 x D. = (0.60 + 0.50 ) x 2 x 0.55. = 1.21 m2Bitumen paint Area = peripheral length x Depth + top area ‐ Column Area.
What are the impacts of eccentric loading on footing?
The reduction in contact area results in the reduction of effective width of footing resulting in decrease in bearing capacity of supporting soil [3]. Eccentric loading of footing can occur in extreme column footing or due to earthquake or wind loading.
What is an example of eccentric?
Eccentric is defined as someone or something that is different or behaves in an unconventional way. An example of eccentric is an adult wearing footy pajamas to a formal dinner. A euphemism for someone who is crazy and rich, as opposed to being just plain crazy like the rest of us. Not having the same center.
What is concentric and eccentric?
In a concentric contraction, the muscle tension rises to meet the resistance then remains stable as the muscle shortens. During eccentric contraction, the muscle lengthens as the resistance becomes greater than the force the muscle is producing.
What is the eccentric phase?
Finally, the eccentric phase is the portion following the isometric phase, in which the muscle is lengthened under load to return to its starting position. Eccentric training focuses on this last portion of the movement, making it more challenging by slowing down the cadence, or speed, of the eccentric phase.
What is eccentricity in rotors?
Eccentricity is the measurement of the rotor bow at slow speed through a suitable sensor. The type of sensor deployed to measure the eccentricity of the shaft is essentially the noncontact pickup, sometimes called a displacement or eddy current or even a proximity pickup. It may be caused by any or a combination of a misalignment, a fixed mechanical bow (bend)/temporary thermal bow, or a bow due to gravitational force. It also may be used to calculate the shaft attitude angle, which is an indicator of rotor stability.
What happens to the eccentricity of the loading forces on an overlap joint?
Eccentricity of the loading forces on an overlap joint results in bending deformation of the joint , thereby introducing additional normal stresses in the bondline. These stresses have a tendency to peel the two adherends apart (see Fig. 8.14 ). With increasing adherend thickness the eccentricity increases, that is slightly higher peel stresses are introduced, which partly counteract the positive effect that the larger adherend thickness has on the shear stress distribution. More importantly, the induced bending deformation also causes a stress concentration in the adherend just in front of the thickness change. This stress concentration, which increases with the thickness of the bonded doubler and the stiffness of the adhesive, can be detrimental to the fatigue strength of the structure.
Why is eccentric loading more cumbersome?
In case of footings subjected to eccentric loading the design is more cumbersome, because the procedure of finding the reduced effective width and area of footing subjected to an eccentric load is time consuming. 2. Initially the eccentricity of the applied load needs to be calculated.
What is the behaviour of foundation structures?
Foundation structures undergo soil-structure interaction. Therefore, the behaviour of foundation structures depends on the properties of structural materials and soil. 2. Accurate estimations of all types of loads, moments and forces are needed for the present as well as for future expansion, if applicable.
Is a foundation design completed before design of other components?
So, in a project, foundation design and details are completed before designs of other components are undertaken. However, it is worth mentioning that the design of foundation structures is somewhat different from the design of other elements of superstructure due to the reasons given below.
What is eccentric footing?
The eccentric footing is a spread or wall footing that must resist a moment in addition to the axial column load and it has the shape of the shoe.
Is an eccentric footing more economical than a combined footing?
This footing has to be done in cases where neighbor’s construction exists and it is not possible to adopt spread footings. When the allowable soil pressure is relatively high and the distance between the columns is large then an eccentric footing is more economical than a combined footing.
What is foundation design?
foundation is defined as the engineered interface between the earth and the structure it supports that transmits the loads to the soil or rock. The design differs from structural design in that the choices in material and framing system are not available, and quality of materials cannot be assured. Foundation design is dependent on geology and climate of the site.
What is considered a retention wall?
Retaining Walls – A wall that retains soil or other materials, and must resist sliding and overturning. Can have counterforts, buttresses or keys.
What causes seismic instabilities?
Fissures or fault lines can cause seismic instabilities. A geotechnical engineer or engineering service can use tests on soil bearings from the site to determine the ultimate bearing capacity, q. u. Allowable stress design is utilized for soils because of the variability do determine the allowable bearing capacity, q.
What causes a disturbed foundation?
Disturbed and/or contaminated foundation material encountered at the planned bottom of footing elevation is unacceptable and must be corrected even if the material itself is suitable. Disturbance of the foundation-bearing surface usually is caused by the excavation means and methods, including excavating below the footing elevation or disturbing the grade with the teeth on the excavator bucket. Contamination usually is due to the presence of water (typically uncontrolled) or sloughing. All disturbed or contaminated material must be removed to expose a suitable foundation surface. The foundation must then be restored by the Contractor, at the Contractor’s expense, to a condition at least equal to the undisturbed foundation as determined by the Engineer.
What is the importance of confirming suitable foundation material?
The importance of confirming suitable foundation material cannot be overstated. The Engineer is responsible for determining the foundation suitability as it relates to the design intent. That is, the foundation material has to have the minimum material properties required for the structure to behave as the Designer intended. Simple tests can be performed in the field to determine the bearing capacity and verify the suitability of the foundation material. They are discussed in the Caltrans Soil and Rock Logging, Classification, and Presentation Manual and include:
What is trenching and excavation?
Excavation and trenching are inherent when constructing foundation elements, such as footing foundations. The Caltrans Trenching and Shoring Manual provides information about the complete process for administering, designing and reviewing excavation work and plans. What follows is a brief description of what to consider before excavation.
What is a Caltrans trenching and shoring plan?
The Caltrans Trenching and Shoring Manual provides procedures for reviewing and authorizing these plans. An important consideration in shored excavations is the minimum setback for a surcharge when on level ground. The setback usually is equal to the depth of the excavation unless specific surcharge loads are considered in the shoring design. The “Boussinesq” strip load formula is recommended for calculating the lateral pressures due to surcharge. (Figure 4-11). For example, no minimum setback of the surcharge load would be required if the earth support system is designed for the summation of lateral pressures due to the surcharge and earth pressures. However, a barrier should be provided to prevent material from entering the excavation. The Caltrans Trenching and Shoring Manual includes several examples of how this formula is used, and the SC website has a spreadsheet that can be used to calculate the pressures7.
