raft foundation reinforcement details pdf

Haque) 2 Shallow Foundations – are usually located no more than 6 ft below the lowest finished floor. These details are not suitable where deep drains or trees can affect the foundation. endstream It is desired to design the raft slab shown below to support the column loads for a building as given below. This construction article provides the detail construction methods for raft foundation of a building. • The bearing capacity increased by combining all individual footings in to one mat –since bearing capacity … Raft foundation A raft foundation is a foundation continuous in two directions, usually covering an area equal to or greater than the base area of the structure. A raft foundation may be rectangular(Fig. The edge of the raft is stepped, creating a toe, which allows the outer leaf of the wall to continue below ground level. 29) bars have been provided at 15 in. The column with 800/250 section, in the common wall of the building, is partially supported by the strip foundation that has a web of 350/800. There is a probability of uplift of structure when the groundwater table rises making nearby soil with more pore water pressure. A short summary of this paper. foundation design for an earthquake resistance is one of the most important parts to be considered in the structural analysis and design. 9 (No. The raft foundation is conducted for the multistory buildings or building having heavy loads. endobj Jul 30, 2016 - Typical Wall Construction Detail on Raft Foundation In construction work, steel bar over lapping plays an important role. <>>> The unified solid raft foundation is the simplest form of foundation and its formwork assembling as well as its reinforcement is usually very easy. 4 0 obj Download. 3 0 obj Beam and slab raft foundation •As a foundation to support the heavier loads of walls or columns, a solid slab raft would require considerable thickness. Detail of raft foundation reinforcement The foundation slabs are reinforced with two wire meshes, one placed at the lower fibers and one at the upper fibers. It is also con templated in this. Design of raft footings is detailed in the following steps. The raft will be used for economical consideration. Download PDF. Seelye 4.2 4.3 Foundation Design by Teng Foundation of Structures by Dunham 4.4 4.5 Indian Standard Code of Practice for Design and Construction of Raft Foundation - IS 2950-1965 Raft Foundation - The Soil Line Method of Design by A.L.L. For example, if the mat foundation is 6 ft (2 m) thick and No. A raft foundation is constructed by first excavating the ground to a uniform, flat level. The strip foundation (inverted T-beam) behaves in a way similar to that of spread footings tied together by a connecting beam. Working Principle of Raft Foundation. %���� Raft or mat foundation These are special cases of combined footing where all the columns of the building are having a common foundation (Fig.11.28.11). endobj This paper. The dimensions of the raft should be at least 3m x 2m and the longer dimension should be less than 1.5 times the shorter dimension. The raft foundation is conducted for the multistory buildings or building having heavy loads. Download Full PDF Package. Specifying 2,500 psi refers to a measure of the concrete’s compressive strength. endobj 7 0 obj Section Civil & Geotechnical Engineering Sheet no./rev. These details are only suitable for single storey extensions to domestic buildings. 3). For foundations of such high rise building, normally raft foundation, pile foundation or piled-raft foundation are used. stream 6. 1- Select a trial footing depth: According to ACI Code 15.7, depth of footing above reinforcement is not to be less than 15 cm for footings on soil. endobj endobj Haque) 2 Shallow Foundations – are usually located no more than 6 ft below the lowest finished floor. x��Y�n�F}��G2�V��7nH|���ub�E!䁱�I�̠Џ�%�Zj�d�$�L�rfvf��Yj�z]=ޕ7{�r���ʛ��-��߬�j��8�~�2_���˲z\-_�bo��؛�p0>�LJ.4�� � �/�.,׊�J��p �=}� ��2�.+����9���# �߹£�l�v88AdBo��,���x�L>w/(nmxﳸ`��y�. Lecture Note COSC 421 (M.E. Tomás Callanan Raft Foundation A raft foundation is a large concrete slab covering the whole building area. by Dr.C.Sachpazis Date 23/04/2013 Chk'd by - Date App'd by Date RAFT FOUNDATION DESIGN (BS8110 : PART 1 : 1997) Raft and soil definition Soil definition Allowable bearing pressure; q Sometimes area covered by raft may be greater than the contact area depending on the bearing capacity of the soil underneath. 6 0 obj Jul 30, 2016 - Typical Wall Construction Detail on Raft Foundation. Patrick Kinyanjui. Structville Integrated Services To download the above named textbook, click on the image below; 4 0 obj 1 Calc. ���. foundations (and foundation walls) is 2,500 pounds per square inch (psi) with higher strength necessary when a foundation is exposed to the weather and the house is located in a moderate or severe weathering probability area as shown in IRC Figure R301.2(3). foundation design for an earthquake resistance is one of the most important parts to be considered in the structural analysis and design. DESIGN OF RAFT FOUNDATION Given Data. stream The details of reinforcement of the raft … Click to View. endobj You will also learn the required quantity of lapping, errors in lapping and how to fix them. 8 0 obj 2 0 obj 3.6 Foundation Soils 6 3.7 Flow Diagrams 6 4.0 CONSTRUCTION DETAILS 9 4.1 Pod Layout 9 4.2 Edge Beam Width and Reinforcement 9 4.3 Internal Ribs (non load bearing) Width and Reinforcement 9 4.4 Internal Ribs (load bearing) Width and Reinforcement 9 4.5 Point loads 9 4.6 Mesh Reinforcement 11 4.7 Re-entrant Corners 11 (375 mm) on center for the main reinforcement in each direction for both top and bottom reinforcement, any additional bars … DESIGN OF RAFT FOUNDATION Given Data. <> Analysis of the raft slab by rigid approach A little consideration of Figure 3 will show that the foundation is loaded is symmetrically in the x-direction, therefore we will compute the eccentricity of the load in the z-direction. Details of the mat configuration are reported in the section on “Geometry.” 3 2 - MATERIAL ... (raft) foundation is made up of a contiguous slab with overall dimensions 93.33 x 54.88 ft (Fig. Noting that 7.5 cm of clear concrete cover is required if concrete is cast against soil, a practical minimum depth is taken as 25 cm. Raft Foundation- Adding Hardcore Since this is our second A3 drawing, neatness and accuracy are key components in marking schemes. 1 0 obj ... Reinforcement, where necessary to meet the design specifications and the governing It is costlier than individual foundation. Detailed Drawing of Raft Foundation. Ist Edition, Volume 1. endobj 5 0 obj Raft or Mat foundation . Tomás Callanan Raft Foundation A raft foundation is a large concrete slab covering the whole building area. Design Example of a Flat Raft Foundation. A shallow foundation system generally used when (1) the soil close the ground surface has sufficient … Rafts consists of a reinforced concrete slab up to 300mm thick, with the slab thicker under When mat foundation is supported by columns rather than […] Jul 30, 2016 - Typical Wall Construction Detail on Raft Foundation. E.S. Strip foundation in which the web extends beyond the column face. They are used when column loads or other structural loads Noting that 7.5 cm of clear concrete cover is required if concrete is cast against soil, a practical minimum depth is taken as 25 cm. spacing for the main reinforcement. <> <> Design of raft footings is detailed in the following steps. endobj L�6�>h +�a �'�Ǟܴ��H>�:�l�����Ӎ�p]�`�����\����T/'�L��U.e6��矩T�m*�6FU�]�k��Q`�5\9��Վ���!� All columns are 230 x 450mm, the grade of concrete (f ck) is 30 N/mm 2, and the yield strength of the reinforcement (f yk) is 500 N/mm 2. endobj Lecture Note COSC 421 (M.E. %���� 4. In addition, an upper radial and tangential reinforcement 5 Φ 14 [mm/ m] is used at the cantilever ring. H^Xf���o�v��]�!��$!�M���������1�r�a]ª�^�7����M�:��Y@^4�O.N�+�3?�8K���+L�i������_*�ì�\�]j�Y • It is used where the supporting soil has low bearing capacity. %PDF-1.5 4. A small square mesh 5 Φ 14 [mm/ m], each side is 1.0 [m], is used at the center of the raft to connect the bottom radial reinforcement. 1) or circular(Fig. 4-1). The raft … Rafts consists of a reinforced concrete slab up to 300mm thick, with the slab thicker under Step 1: Initially, the surveyor should begin exaction and as soon as the survey is completed then exaction is carried out to the desired level on the basis of the validated shop drawings. �#�s^�,z��]��l'��U>Mũ�1���҉�~۷7� ����3���i��'��Vɜ��ଲa�� ���?MD+ Normally, for buildings with heavy loads or when the soil condition is poor, raft foundations are very much useful to control differential settlement and transfer the loads not At the end of the drawing we will add all of the annotation and number each element on Disadvantages of raft foundation. 5. From this point onwards do not add any annotation. The structure moves together with the raft foundation when ground movements occur such that cracking or damage can be prevented. The dimensions of the raft should be at least 3m x 2m and the longer dimension should be less than 1.5 times the shorter dimension. ��N�,����"��{�. However, due to the fact that the footing and the inverted T-beam’s web form a unified body along the entire length of the structure, the system’s inertia is larger therefore, its behaviour is more satisfactory These details are not suitable where deep drains or trees can affect the foundation. x�U�Mk1E�����L�&/1�gTZ��@҅�3�p����M����q�����\��sZ,��J|qF ED�Z�����r��c��3���C��N8�f�$d�K����Ayca�W�?P�� 1�C� gzm��J��͕ɚjcT���- Typical raft foundation – slab on the ground with thickened edge beam Raft foundations are used to spread the load from a structure over a large area, normally the entire area of the structure. <> All loads are transmitted through the raft to the soil Rafts are suitable for low load bearing soils, such as soft natural ground or made-up ground. DESIGN OF RAFT FOUNDATION Given Data. Raft Foundation Design for a Typical 2 Storey House Example (BS8110 : PART 1 : 1997) Job Ref. <> <>>> Design of Raft Foundation Page | 9 3. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 9 0 obj <> Figure 3.8 shows a raft foundation strengthened by main and secondary beams, and with filling placed over to carry the floor at the appropriate level. • Mat or raft foundation is a large concrete slab supporting several columns in two or more rows. x��Vˎ�:��?p)�$�/`0�N������.�XI$vj93�ߗ����W3;?D����~���ۧ�Ǐ ������1I�BJ���)�ZBl$4nT�������,^OK�(i���ƣ��#4x8¿�HtIl��ZD��Y��� �äv�>L0�g��dN1&:M��`�H� LքdХ��/��w��|�>MNЃ �0@�R �H Types of raft foundation and example usage. Seelye 4.2 4.3 Foundation Design by Teng Foundation of Structures by Dunham 4.4 4.5 Indian Standard Code of Practice for Design and Construction of Raft Foundation - IS 2950-1965 Raft Foundation - The Soil Line Method of Design by A.L.L. <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.44 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Design of Pad Footing Cracking & Detailing Requirements • All reinforcements should extend the full length of the footing • If >1.5 +3 , at least two-thirds of the reinforcement parallel to L y should be concentrated in a band width +3 centred at column where L x & L y and c x & c y are the footing and column dimension in x and y directions 23 Full PDFs related to this paper. This Raft Foundation Method Statement template has been prepared and pre-completed for the excavation and construction of a reinforced concrete raft foundation. The unnecessary area where there is no significant stress, there also the reinforcement is used. Raft foundation is generally used to support structures like residential or commercial buildings where soil condition is poor, storage tanks, silos, foundations for heavy industrial equipment etc. thesis to study, the effect of chang e of a number of floors, spacing between. Raft foundations (also called slab-on-the-ground foundations or floating slabs). Then, a waterproof plastic sheet is laid over the earth, and a thin 3" layer of plain cement concrete (PCC) is poured just to create a perfectly flat and level base for the foundation. @3U���NΏ_RϏ&�L�E��PJq���K�a�����B�w| One meter edge is around the edges columns. The plan of the raft is shown in figure 1. (2017): Practical Structural Analysis and Design of Residential Buildings Using Staad Pro V8i, CSC Orion, and Manual Calculations. Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. These details are only suitable for single storey extensions to domestic buildings. READ PAPER. 3 0 obj Jul 30, 2016 - Typical Wall Construction Detail on Raft Foundation. Raft or Mat foundation . The first type – solid slab rafts – can be further divided as flat raft … Figure 1, Raft … A raft or mat foundation is a sizable concrete slab or slab-and-beam system which supports all the loads of superstructure through walls or columns in two or more rows and rests on soil layer or rock. %PDF-1.5 Patrick Kinyanjui. In general at joint areas either at the superstructure or the foundation, it is advisable to place stirrups in the columns and the beams. endobj Raft Modeling and Analysis: 3.1.0 Raft dimensions: Raft foundation has been modeled in SAFE software. To make the most economical use of reinforced concrete in a raft foundation supporting heavier loads, it is usual practice to form a beam and slab raft. The raft has x side spacing of 7 meters and y-side spacing of 6 meters. Raft foundation construction details. The concrete raft is supported on a compacted hardcore base which extends out past the edge of the raft. 2 0 obj <>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 9 0 R/Group<>/Tabs/S/StructParents 1>> E.S. 5. 3. endobj There are five main types of raft foundation: Solid slab rafts, Slab beam rafts, Cellular rafts, Piled raft foundations; and, Balancing (or floating) rafts. 3. <> stream Design of Pad Footing Cracking & Detailing Requirements • All reinforcements should extend the full length of the footing • If >1.5 +3 , at least two-thirds of the reinforcement parallel to L y should be concentrated in a band width +3 centred at column where L x & L y and c x & c y are the footing and column dimension in x and y directions In cases where the depth of excavation to firm ground exceeds the structural depth of the raft foundation, the excess depth over the raft can be filled with weak concrete or compacted broken stone. 1- Select a trial footing depth: According to ACI Code 15.7, depth of footing above reinforcement is not to be less than 15 cm for footings on soil. Sum of load on gridline D = 79 + 168 + 168 + 79 = 494 kN Sum of load on gridline C = 173 + 384 + 384 + 173 = 1114 kN To get a better idea about when to use raft foundation, it is important to understand how raft foundation works. All loads are transmitted through the raft to the soil Rafts are suitable for low load bearing soils, such as soft natural ground or made-up ground. <> Raft Foundation - Construction Studies Q1. For foundations of such high rise building, normally raft foundation, pile foundation or piled-raft foundation are used. 1 0 obj Manual Design of Beam and Raft Foundation to Eurocode 2 [PDF] References Ubani O.U. A shallow foundation system generally used when (1) the soil close the ground surface has sufficient … The method statement includes a safe work procedure and control measures, which you can edit and add your project details. In this useful construction video tutorial, you will learn how to place lapping in exact position in raft foundation. tool for a better design of raft foundation.

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