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Concrete Gravity and Gravity Arch Dams
A concrete gravity dam has a cross-section such that, with a flat bottom, the dam is free-standing that is, the dam has a center of gravity low enough that the dam will not topple if unsupported at the abutments. Gravity dams require maximum amounts of concrete for their construction as compared with other types of concrete dams, and resist dislocation by the hydrostatic pressure of reservoir water by sheer weight. Concrete gravity dams have been constructed up to 285 m (950 ft)high. Properly...
Suspended Timber Flooring
A suspended flooring system generally comprises a series of joists closely spaced, being either simply supported at their ends or continuous over load-bearing partition walls. The floor boarding or decking is applied on the top of the joists and underneath ceiling linings are fixed. A typical suspended floor arrangement is shown in Figure 1.18a. The distance between the centres of the joists is normally governed by the size of the decking and ceiling boards, which are normally available in...
Top 10 Best Built-in Wine Coolers
The best Built-in wine coolers is a must-have appliance for any wine lover to preserve his expensive collection. Wines can downgrade in quality if they are not kept at optimum temperatures. Wine coolers play a significant role in storing the wines at just the right condition without compromising the flavor. The wide collection of coolers is available in the market that may create a dilemma in customer's mind.
Top 10 Best Slide-in Gas Ranges
If you have a modular kitchen and there is less space available, a slide-in gas range is the best choice for you. When it comes to buying a range, you have two options to choose from. The first one is freestanding range and the second one is the slide-in gas ranges. Freestanding ones are quite common as you can fit them in any part of your kitchen and there is no need for cabinetry work. They can stand on their own and they can be put in between cabinets.
Peripheral Ties In Buildings
6.6 Other serviceability requirements The two principal other serviceability considerations are those of durability and resistance to fire, although occasionally a situation arises in which some other factor may be of importance to ensure the proper performance of a structural member in service. This may include fatigue due to moving loads or machinery, or specific thermal and sound insulation properties. The methods of dealing with such requirements may range from the use of reduced working...
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Strength behaviour
Ring and shear-plate connectors are circular in shape and manufactured from aluminium alloy, hot rolled or temper rolled steel strip, hot rolled steel alloy strip, grey cast iron or cast metal, in accordance with the requirements of BS EN 912. They fit into preformed grooves in the timber members that accurately profile the connector and are capable of taking much greater loads than are achievable with toothed-plate connectors. The strength equations for these types of connectors are given in...
Main types of compaction plant
The three main types of compaction equipment are The compaction plant described below is categorised in terms of total mass. The static mass per metre width of roll is the total mass on the roll divided by the width of the roll. Where a roller has more than one axle the machine's category is determined using the roller which gives the greatest value of mass per unit width. Probably the most commonly used roller in the world is the smooth wheeled roller. It consists of hollow steel drums so that...
Consolidation during construction
A sufficiently accurate solution is generally achieved by assuming that the entire foundation load is applied halfway through the construction period. For large constructions, spread over some years, it is sometimes useful to know the amount of consolidation that will have taken place by the end of construction, the problem being that whilst consolidating the clay is subjected to an increasing load. Figure 10.9 illustrates the loading diagram during and after construction. While excavation is...
E P Curve Overconsolidated Clay
By way of illustration let us use the test results of Example 9.4 together with the following information Original dimensions of test sample 75 mm diameter, 20 mm thickness Mass of sample after removing complete from consolidation apparatus at end of test and drying in oven 135.6 g. Ms 135.6 g A x 752 4418 mm2 Hs -- 11.58mm Hence the void ratio to pressure relationship can be found. Pressure kN m2 Thickness H e - Note Such close agreement between the two methods for determining the e-p...
Influence charts for vertical stress increments
It may not be possible to employ Fadum's method for irregularly shaped foundations and a numerical solution is then only possible by the use of Boussinesq's coefficients, K, and the principle of superposition. Fig. 4.8 The Newmark chart for vertical stress under a foundation. Fig. 4.8 The Newmark chart for vertical stress under a foundation. An alternative method that removes the numerical work is to utilise the influence charts devised by Newmark in 1942 Fig. 4.8 . It can be shown that, at a...
How To Plot Strength Envelope With Respect To Total Stresses
Plot the strength envelope of the soil (a) with respect to total stresses and (b) with respect to effective stresses. The two Mohr circle diagrams are shown in Fig. 3.23. The total stress circles are obtained as previously described and are shown with full lines. To determine an effective stress circle it is necessary to subtract the pore water pressure for that circle from each of the principal stresses, e.g. for a cell pressure of 200kN m2 the major principal total stress was 200+ 118 318kN...
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Permanent actions
The densities and weights of commonly used materials, sheet materials and forms of construction are given in Table 2.5. Table 2.5 Typical permanent actions 24 Table 2.5 a) Bulk densities for soils and materials Table 2.5 a) Bulk densities for soils and materials Limestone (Portland stone - med. weight) Table 2.5 b) Typical area loads for concrete slabs and sheet materials Quarry tiles including mortar bedding Waffle slabc - standard moulds (325 mm) Waffle slabc - standard moulds (425 mm) Waffle...
Section Lightweight Concrete
11.1 11.3 SECTION 1 SYMBOLS SECTION 1. SYMBOLS For the purposes of this document, the following symbols apply. Note the notation used is based on ISO 3898 1987 Ac Cross sectional area of concrete Ap Area of a prestressing tendon or tendons As Cross sectional area of reinforcement As,min minimum cross sectional area of reinforcement Asw Cross sectional area of shear reinforcement Ec, Ec 28 Tangent modulus of elasticity of normal weight concrete at a stress of Oc 0 Ec,eff Effective modulus of...
Concrete Design By Dass Euro Code
Lightly stressed when p equals 0.5 per cent, p is given by l 0Aymi l gt d where i4s,rCq i the area of tension reinforcement required in the section. Interpolation between the values of p indicated is permissible. In the case of slabs it is reasonable to assume lha they are lightly stressed. Since the value of allowable span-effective depth ratio is affected by both reinforcement ratio and concrete strength it may be more convenient to use the char in figure 6.3 which is for a simply supported...
Membrane analogy
It has been stated earlier that the mathematical solution for the torsion of certain solid and thin-walled sections is complex and beyond the scope of this text. In such cases it is extremely fortunate that an analogy exists known as the membrane analogy, which provides a very convenient mental picture of the way in which stresses build up in such components and allows experimental determination of their values. It can be shown that the mathematical solution for elastic torsion problems...
Bent Up Bars In Beams
Total ultimate load on beam 200 x 8.0 1600kN Support reaction 1600 2 800 kN Shear, Vtl at face of support 800 - 200 x 0.3 2 770 kN Shear. Vu distance ct from face of support 770 200 x 0.65 640 kN 1. Check the crushing strength VRd maxof the concrete diagonal strut at the face of the beams support. 0.124 x 350 x 650 1 - 30 250 30 745 kN lt Vnf 770kN VWmax lt 45 0.18MC1 ck 250 ck 0.18 x 350 x 650 1 30 250 30 1081 kN gt VEf 770kN 2. Determine angle 0 From equation 5.8 a or alternatively from...
Strain Tensor
8 Following the simplified and restrictive introduction to strain, we now turn our attention to a rigorous presentation of this important deformation tensor. 9 The approach we will take in this section is as follows 1. Define Material fixed, Xj and Spatial moving, Xj coordinate systems. 2. Introduce the notion of a position and of a displacement vector, U, u, with respect to either coordinate system . 3. Introduce Lagrangian and Eulerian descriptions. 4. Introduce the notion of a material...
Accidental design situation
(1) Unless otherwise specified, for design situations during which there is a risk of loss of static equilibrium, the combination of actions to be considered should be based on a single accidental action 0ci,k is one of the groups of construction loads defined in 4.8 (i.e. QCb, Qcc or QCd). Note This combination of actions is different from the general combination defined in ENV 1991-1. It is proposed here for the sake of simplicity, to avoid the definition of frequent values of the variable...
Filter Aids
Filter aids as well as flocculants are employed to improve the filtration characteristics of hard-to-filter suspensions. A filter aid is a finely divided solid material, consisting of hard, strong particles that are, en masse, incompressible. The most common filter aids are applied as an admix to the suspension. These include diatomaceous earth, expanded perlite, Solkafloc, fly ash, or carbon. Filter aids build up a porous, permeable, and rigid lattice structure that retains solid particles and...
Confinement reinforcement in the critical regions of columns and ductile walls
The longitudinal reinforcement of columns and walls is normally symmetric, p, p2. So, the Clauses value of i0 specified via equations D5.ll for the plastic hinges cannot be provided as in 5.4.3.2.2 7 , beams, i.e. by keeping the extreme concrete fibres below their ultimate strain through a low 5.4.3.2.2 8 , difference between the tension and compression reinforcement ratios, px - p2 cf. equation 5.4.3.4.2 2 , D5.23 . In columns and walls we let, instead, the extreme concrete fibres reach their...
Performance requirements for new designs In Eurocode and associated seismic hazard levels
As a European standard EN , Part 1 of Eurocode 8 provides for a two-level seismic design Clause 2.1 1 with the following explicit performance objectives No- local- collapse protection of life under a rare seismic action, through prevention of collapse of the structure or its parts and retention of structural integrity and residual load capacity after the event. This implies that the structure is significantly damaged, and may have moderate permanent drifts, but retains its full vertical...
Regularity in plan
Regularity in plan influences essentially the choice of the structural model. The reasoning Clause 4.2.3.2 behind the provisions of EN 1998-1 in this respect is that structures that are regular in plan tend to respond to seismic excitation along their main structural directions in an uncoupled manner. Accordingly, for the design of regular structures in plan it is acceptable to analyse them in a simplified way, using planar models in each main structural direction. 4.3.2.1. Criteria for...
Column Eccentricity
Modulus of elasticity of the concrete see 3.1.2.5.2 moment of inertia gross section of the column or beam respectively height of the column measured between centres of restraint effective span of the beam factor taking into account the conditions of restraint of the beam at the opposite end 1.0 opposite end elastically or rigidly restrained 0.5 opposite end free to rotate 0 for a cantilever beam. 2 Isolated columns are considered slender if the slenderness ratio of the column considered exceeds...
Links Reinforcement
It is also permitted to use a diagram in which the resisting tensile force is progressively decreasing on the length lb,net. Figure 5.11 Envelop line for the design of flexural members. Anchorage lengths 3 The anchorage lengths of bent-up bars which contribute to the resistance to shear should be not less than 1.3 lb,net in the tension zone and 0.7 lb,net in the compression zone. 5.4.2.1.4 Anchorage of bottom reinforcement at an end support 1 Over supports with little or no end fixity it is...
Equivalent Anchorage Length Forstandard Bend
Minimum internal radius of a hook, bend or loop 2o or 3.So for 0 > 16 mm Equivalent anchorage lengths for bends and hooks satisfy the minimum dimensions shown in figure 5.11. Bends and hooks are not recommended for use as compression anchorages. In the case of the hooks and bends shown in ligure 5.11 the anchorage length (shown as b,eq) which is equivalent to that required by the straight bar can be simply calculated from the expression b,eq 0 'b,rqd where r.) is taken as 0.7 or 1.0 depending...
Soil Water Permeability and Flow
This is the term used to define all water found beneath the Earth's surface. The main source of subsurface water is rainfall, which percolates downwards to fill up the voids and interstices. Water can penetrate to a considerable depth, estimated to be as much as 12000 metres, but at depths greater than this, due to the large pressures involved, the interstices have been closed by plastic flow of the rocks. Below this level water cannot exist in a free state, although it is often found in...
Limitation of interstorey drift
(1) Unless otherwise specified in Sections 5 to 9, the following limits shall be observed a) for buildings having non-structural elements of brittle materials attached to the structure b) for buildings having ductile non-structural elements c) for buildings having non-structural elements fixed in a way so as not to interfere with structural deformations, or without non-structural elements dr is the design interstorey drift as defined in 4.4.2.2(2) h is the storey height v is the reduction...
Verification of beamcolumn joints in shear
Clauses Assuming that bond strength along the beam and column bars framing the joint core is 5.5.3.3 I , sufficient to transfer into the joint the full shear force demand, given by equation D5.20 in 5.5.3.3 2 , terms of the horizontal shear force, Vjhd, the body of the joint then resists that shear. This 5.5.3.3 3 shear force is translated into a shear stress, considered uniform within the joint volume, defined by the horizontal distance between the extreme layers of column reinforcement, h-,...
Experimental Stress Analysis
We live today in a complex world of manmade structures and machines. We work in buildings which may be many storeys high and travel in cars and ships, trains and planes we build huge bridges and concrete dams and send mammoth rockets into space. Such is our confidence in the modern engineer that we take these manmade structures for granted. We assume that the bridge will not collapse under the weight of the car and that the wings will not fall away from the aircraft. We are confident that the...
Isotropic consolidation
Most soil samples tested in the triaxial apparatus are isotropically consolidated, i.e. consolidated under an all-round hydrostatic pressure, before the commencement of the shearing part of the test. It is appreciated that other forms of consolidation are possible, e.g. K0 consolidation, but these forms will not be considered here. The form of the compression curve for an isotropically consolidated clay is shown in Fig. 13.1a. It should be noted that the plot is in the form of a v-p', plot the...
Distributed Force On Nodes Finite Element
In many thin structures modeled as continuous bodies the appearance of skinny elements is inevitable on account of computational economy reasons. An example is provided by the three-dimensional modeling of layered composites in aerospace and mechanical engineering problems. A physical interface, resulting from example from a change in material, should also be an interelement boundary. That is, elements must not cross interfaces. See Figure 8.3. In two-dimensional FE modeling, if you have a...
Mohr Circles In Soil Mechanics
12.8.2 Alternative and safer way to determine c' and 4 gt for an unsaturated soil Procedure is to first fully saturate the sample and then to determine c' and 4 gt '. A pressure source is connected to the pore water in the sample which is then increased in pressure. This increase in pressure is referred to as the back water pressure and must be of sufficient intensity so that any air present in the soil will dissolve into the soil water and the sample will become fully saturated. The sample is...
Skempton A. W. 1954. The Pore-pressure Coefficient A And B.
Alonso, E.E., Gens, A. and Hight, D.W. 1987 'Special problem soils'. General Report. Proc 9th Eur. Conf. Soil Mech., 3, Dublin. Alonso, E.E., Gens, A. and Josa, A. 1990 'A constitutive model for partially saturated soils', Geotechnique, 40, 3 . American Society for Testing and Materials 1980 Natural building stones, soil and rock. Annual book of ASTM Standards. Philadelphia, Pennsylvania. Atkinson, J.H. and Bransby, P.L. 1978 The mechanics of soils - an introduction to critical state soil...
Fadum S Method Chart
A concentrated load of 400 kN acts on the surface of a soil. Determine the vertical stress increments at points directly beneath the load to a depth of 10 m. For points below the load r 0 and at all depths r z 0, whilst from Fig. 4.5 it is seen that K 0.48. This method is only applicable to a point load, which is a rare occurrence in soil mechanics, but the method can be extended by the principle of superposition to cover the case of a foundation exerting a uniform pressure on the soil. A plan...
Closed Hydraulic Piezometer
In the case of lagoons a sudden drawdown in the level of the slurry is unlikely, but the problem is important in the case of a normal earth dam. Bishop 1954 considered the case of the upstream face of a dam subjected to this effect, the slope having a rock fill protection as shown in Fig. 5.20. A simplified expression for u under these conditions is obtained by the following calculation Fig. 5.19 Determination of excess head at a point on a flow net. Fig. 5.19 Determination of excess head at a...
Computers in surveying
Computers have, throughout their development, been extremely important in the fields of surveying and mapping. Initially, their use was almost exclusively restricted to the 'number crunching' requirements of large organizations carrying out geodetic computations or the adjustment of major control frameworks. Operations of this type were carried out on large mainframe computers in batch mode. Whilst slow and cumbersome to operate by modern computing standards, these early computers offered...
Counterfort Wall
Such walls are usually required to resist a combination of earth and hydrostatic loadings. The fundamental requirement is that the wall is capable of holding the retained material in place without undue movement arising from deflection, overturning or sliding. Concrete retaining walls may be considered in terms of three basic categories I gravity. 2 counterfort, and 3 cantilever. Within these groups many common variations exist, for example cantilever walls may have additional supporting ties...
Effects Of Overflow And Underflow In Wastewater
Shows effect of underflow rate on thickening capacity. The curves of concentration as a function of depth in the compression zone are essentially vertical displacements of each other and are similar to those observed in batch sedimentation. When the sludge rakes operate, they essentially break up a semirigid structure of concentrated sludge. Generally, this action extends to several inches above the rakes and contributes to a more concentrated underflow. The required height of the...
Load Penetration Curve Of Compacted Soil
gt T r Sub-base - lt The value of the stiffness modulus of the subgrade is required if the stresses and strains in the pavement and the subgrade are to be calculated. Subgrade strength is expressed in terms of its California Bearing Ratio CBR value. The CBR value is measured by an empirical test devised by the California State Highway Association and is simply the resistance to a penetration of 2.54 mm of a standard cylindrical plunger of 49.6 mm diameter, expressed as a percentage of the...
Soil Mechanics Info
The standard force penetration curve, corresponding to 100 per cent CBR has the following values Plunger penetration mm 2 4 6 8 Plunger load kN 11.5 17.6 22.2 26.3 Determine the CBR value of the subgrade. Solution The standard penetration curve is shown drawn in Fig. 11.12. The test points are plotted and a smooth curve drawn through them. In this case there is no need for the correction procedure as the curve is concave upwards in its initial stages. From the test curve it is seen that at 2.5...
The Pressure Leaf Filter
This device is similar to a plate-and-frame filter press but the whole plate assembly is also housed in a tank or pressure vessel. This design allows higher pressures to be used, and also allows the filtration operation to be done more efficiently in many applications. There are two basic configurations, namely a horizontal plate and a vertical pressure leaf filter. Horizontal plate pressure filters were commonly applied to the fine chemical process industries such as antibiotics , pesticides...
Ribbed or waffle slabs
Current practices for determining forces in ribbed and waffle slabs may also be used for designs to Eurocode 2.Where a waffle slab is treated as a two-way slab refer to previous section, but note that their torsional stiffness is significantly less than for a two-way slab and the bending moment coefficients may not be appiicabie.Where it is treated as a flat slab reference may be made to Chapter 7, originally published as Flat slabs4 The position of the neutral axis in the rib should be...
Equivalent Horizontal Force Eurocode Concrete
(2) These values are assumed to take account of differences between the strength of test specimens of the structural materials and their strength in situ. (3) The values given above are valid when the quality control procedures given in chapter 7 are followed. They apply to characteristic values defined in chapter 3 and for design data as described in chapter 4.2. (4) Higher or lower values of Yc may be used if these are justified by adequate control procedures. (5) These values do not apply...
Material properties
In Eurocode 2 the design of reinforced concrete is based on the characteristic cylinder strength rather than cube strength and should be specified according to BS 8500 Concrete - complementary British Standard to BS EN 206-17 (e.g. for class C28 35 concrete the cylinder strength is 28 MPa, whereas the cube strength is 35 MPa). Typical concrete properties are given in Table 4. Concrete up to class C90 105 can be designed using Eurocode 2. For classes above C50 60, however, there are additional...
Methods for calculating deflections
Two methods for calculating deflection are presented below, and these are based on the advice in TR58 Deflections in concrete slabs and beams8 The rigorous method for calculating deflections is the most appropriate method for determining a realistic estimate of deflection. However, it is only suitable for use with computer software. The Concrete Centre has produced a number of spreadsheets that use this method to carry out deflection calculations for a variety of slabs and beams9. These offer a...
Simply supported oneway slab simple version
This calculation is intended to show a typical hand calculation. A 175 mm thick slab is required to support screed, finishes, an office variable action of 2.5 kN m2 and demountable partitions 2 kN m . The slab is supported on load-bearing block walls. ck 30, yk 500. Assume a 50-year design life and a requirement for 1 hour resistance to fire. Simply supported slab simple version Simply supported slab simple version Self-weight 0.175 x 25 50 mm screed Finishes, services Offices, general use B1...
Fctm Formula Ec2
Slenderness Limit using fctm and fctm,fl Figure 7.24. Slenderness Limit using fctm and fctm,fl As can be seen there is an important difference only for very small reinforcement ratios. For reinforcement ratios larger than 0.6 , the difference is negligible. 7.4.4 Simplified formulae 7.4.4.1 Simplified formula of EC2 The application of the general method of prEN 1992-1 is very tedious and time consuming, since calculations have to be made for many sections. As an alternative to this...
Design grid line grid similar
300 - 30 - 20 - 20 2 240 mm K MEd bd2fck 95.1 x 106 (1000 x 2402 x 30) 0.055 As MEd fydz 95.1 x 106 (228 x 500 1.15) 959 mm2 m (p 0.40 ) Try H16 200 (1005 mm2 m) Allowable l d N x K x F1 x F2 x F3 where N 26.2 (p 0.40 , fck 30) K 1.2 (flat slab) < Concise EC2 Table 15.10> < Concise EC2 Table 15.11> osn 283 MPa (from Concise EC2 Figure 15.3 and Gk Qk 3.6, 0.3, ys 1.25) S redistribution ratio 1.08 (Js 283 x (959 1005) 1.08 250 F3 310 250 1.24 Allowable l d 26.2 x 1.2 x 1.24 39.0 Actual l...
Euro Code Concrte Structures Table
Bending moment coefficients for flat slabs End support slab connection First Interior Interior End End End End support span support span G.GB6FI -G.G4FI G.G7SFI -G.GB6FI G.G63FI 1 Applicable to slabs where the area of each bay exceeds 30 m2, Qk, lt 1.25 Gk and qk lt 5 kN m2 2 F is the total design ultimate load, l is the effective span 3 Minimum span gt 0.85 longest span, minimum 3 spans 4 Based on 20 redistribution at supports and no decrease in span moments Whichever method of analysis is...
Coupling elements of coupled walls
1 P Coupling of walls by means of slabs shall not be taken into account, as it is not effective. 2 The provisions of 5.5.3.1 may only be applied to coupling beams, if either one of the following conditions is fulfilled a Cracking in both diagonal directions is unlikely. An acceptable application rule is b A prevailing flexural mode of failure is ensured. An acceptable application rule is l h gt 3. 3 If neither of the conditions in 2 is met, the resistance to seismic actions should be provided...
Standards and codes of practice referred to in Chapter
BS 12 1978 Specification for ordinary and rapid-hardening Portland cement. BS 146 1973 Part 2 Specification for Portland blast-furnace cement. BS 812 1984 Part 101 Guide to sampling and testing aggregates. BS 877 1973 1977 Part 2 Specification for foamed or expanded blast-furnace slag lightweight aggregate for concrete. BS 882 1983 Specification for aggregates from natural sources for concrete. BS 915 1972 1983 Part 2 Specification for high alumina cement. BS 1014 1975 1986 Specification for...
Seepage and flow nets
A flow net is a graphical representation of the pattern of the seepage or flow of water through a permeable soil. It is possible, by means of a flow net, to calculate the hydrostatic uplift on a structure such as a dam or barrage, the amount of seepage It is common practice to start the analysis by assuming a uniform distribution off(x) (say (.*) 1.0) across the slip. Some authors have indicated that variations in the shape of the f(x) distribution have little effect on the factor of safety...
Geotechnical Design Hand Sketch Borehole Cross Section
12.3.2 Requirements for drive samplers (1)P Drive samplers used as category A sampling methods shall fulfil alll requirements presented in (2) Fulfilling these requirements does not guarantee that totally undisturbed samples will always be obtained, but it should at least minimize the disturbance of samples and thus the effect of such disturbance on the results of laboratory tests performed on these samples. 12.3.2.2 Diameter of the sample tube (1)P For catagory A sampling methods, sample tubes...
Upstream Face Of An Earthen Dam Is Phreatic Line And Equipotential Line
The stress that controls changes in the volume and strength of a soil is known as the effective stress. In Chapter 1 it was seen that a soil mass consists of a collection of mineral particles with voids between them. These voids are filled with water, air and water, or air only (see Fig. 1.10). For the moment let us consider saturated soils only. When a load is applied to such a soil it will be carried by the water in the soil voids (causing an increase in the pore water pressure) or by the...
Preconsolidation Pressure By British Standard Code
Active earth pressure, 196-8, 211-14, 219-21 activity of a clay, 126, 127 adhesion factor, 303 adsorbed water, 61 aeration zone, 35, 36 air dried soils, 9 air voids line, 388 air voids percentage, 396 allowable bearing pressure, 269, 292, 293, 348, 349 analogy of consolidation settlement, 352 backfill, 223 backfill drainage, 224 back pressure, 102, 103 basalt, 2 base materials, frost susceptibility, 407 bearing capacity coefficients, 275, 279, 280 bearing capacity of a pile, determination of,...
Prestressing steel
See note preceeding 3.2 . 3.3.0 Notation see also 1.6, 1.7 Tensile strength of prestressing steel Characteristic tensile strength of prestressing steel 0.1 proof-stress of prestressing steel Characteristic 0.1 proof-stress of prestressing steel Elongation of prestressing steel at maximum load Characteristic elongation of prestressing steel at maximum load P 1 This section applies to wires, bars and strands used as prestressing tendons in concrete structures. P 2 The requirements apply to the...
Enhanced Shear For Pilecap Design In Ec2
There are no specific requirements within EC2 for the distribution of the calculated reinforcement. The provisions of BS 8110 Part 1 Clause 3.11.4.2 are adopted in this example. With piles spaced at 3 times the diameter, the reinforcement may be uniformly distributed. Maximum spacing 3h > 500 500 > 275 mm OK Minimum -- < 0.0015 bd 0.0015 x 2100 x 675 2127 mm2. . OK The reinforcement details are shown in Figure 7.8. The reinforcement details are shown in Figure 7.8. Figure 7.8 Details of...
Reinforcement details
The rules governing the minimum and maximum amounts of reinforcement in a load bearing column are as follows. 1. A minimum of four bars is required in a rectangular column one bar in each corner and six bars in a circular column. Bar diameter should not be less than 12 mm. 2. The minimum area of steel is given by 3. The maximum area of steel, at laps is given by As where As is the total area of longitudinal steel and Ac is the cross-sectional area of the column. Otherwise, in regions away from...
Ec 2 Lever Arm Curve
Maximum value of zjd according to the Concise Code and previous UK practice Compression reinforcement required at M i The percentage values on the axis mark the limits for singly reinforced sections with moment redistribution applied see Section 4.7 and Table 4.2 F,t fyht A, with 7, 1.15 0.87 yiA Hence Equations 4.8 and 4.9 can he used to design the area of tension reinforcement in i singly reinforced concrete section to resist an ultimate moment, M. Equation 4.8 for the lever arm z can also he...
Piles in tension
The procedure for designing piles in tension is similar to that for piles in compression, except that the only design methods recognised are based on load tests or ground test results. The tensile resistance will normally be derived from the shaft resistance only. The partial factor applied will generally be greater than that used for compression piles the ENV and British NAD gives a value of 1.6 in 7.7.2.2 4 P. Designers using Clause 7.7 should first be familiar with 7.6 for compression piles....
Fig Redistribution procedures for frames
The effective span of a simply supported beam should normally be taken as the clear distance between the faces of supports plus one-third of the beam seating width at each end. However, where a bearing pad is provided between the slab and the support, the effective span should be taken as the distance between the centres of the bearing pads. The effective span of a beam continuous over its supports should normally be taken as the distance between the centres of the supports. The effective...
Punching shear
The design value of the punching shear force, Kd, will usually be the support reaction at the ultimate limit state. In principle the design for punching shear in Eurocode 2 and BS 8110 is similar. The main differences are as follows. Standard factors for edge and corner columns that allow for moment transfer B are greater in Eurocode 2. However, B can be calculated directly from Expressions 6.38 to 6.46 of the Eurocode to give more efficient designs. Basic span-to-effective-depth ratios for...
Magnel Diagram Equations
4.08 x 10fi x 24 - 59.4 x ' 0.8 4.08 x 106 70000 - 75 and allowing for the division by the negative denominator P gt -2881 kN Similarly from equations 11.18 lo 11.20 Pn lt 1555 kN P0 gt 557 kN P lt 654 kN The minimum value of preslress force is therefore 557 kN with an upper limit of 654 kN. b Check the upper economic limit to preslress force From equation 11.23 lt 12 x 350 x 200 x 10' 3 0.8 Since this is greater than the upper limit already established from equation 11.20 a design with an...
Good Bond Conditions Concrete
P 1 The quality of the bond depends on the surface pattern of the bar, on the dimension of the member and on the position and inclination of the reinforcement during concreting. 2 For normal weight concrete, the bond conditions are considered to be good for a all bars, with an inclination of 45 to 90 to the horizontal, during concreting Figure 5.1 a b all bars which have an inclination of 10 to 45 to the horizontal during concreting and are either placed in members whose depth in the direction...
The lateral force method of analysis
Introduction the lateral force method versus modal response spectrum analysis In the lateral force method a linear static analysis of the structure is performed under a set of lateral forces applied separately in two orthogonal horizontal directions, X and Y. The intent is to simulate through these forces the peak inertia loads induced by the horizontal component of the seismic action in the two directions, X or Y. Owing to the familiarity and experience of structural engineers with...
Definition and role of primary and secondary seismic elements
Clauses 4.2.2 1 , EN 1998-1 recognizes that a certain number of structural elements which are not essential 4.2.2 3 parts of the seismic-resisting structural system of the building may be considered as'secondary seismic', as far as their role and contribution to earthquake resistance of the building is concerned. The main objective of this distinction is to allow for some simplification of the seismic design by not considering such elements in the structural model used for the seismic analysis...
Behaviour factor q of concrete buildings designed for energy dissipation
In building structures designed for energy dissipation and ductility, the value of the behaviour Clause 5.2.2.2 factor q, by which the elastic spectrum used in linear analysis is reduced, depends on the type of lateral-force-resisting system and on the ductility class selected for the design. As we will see in Section 5.6.3.2 the value of the q factor is linked, directly or indirectly, to the local ductility demands in members and hence to the corresponding detailing requirements. As in DCL...
Pile Negative Friction Eurocode
The designer is allowed to chose between two approaches, treating either forces or displacements as the basic action. The more economic approach may be chosen in each circumstance. An example of this is presented below under C7.3.2.2. C7.3.2.2 Downdrag negative skin friction Downdrag will usually be analysed by calculating the maximum force which could be generated by negative skin friction, following Paragraph 2 , and treating this as an action Paragraph 1 P . This implies that the force will...
Bearing capacity calculations
Using the formulae in Annex B.2 for undrained conditions, the length of side of the footing for Case B was 3.75 m while for Case C is was 4.0 m. Hence, as for E2, Case C is critical and B L 4.0 m. This may be checked as follows. For Case C, the design vertical action at footing base Vertical action Vd yG Gvk Wvii yQ Qvk Wvk weight of pad 1.0 x 1000 24.5 x 4.0 x 4.0 x 0.75 1.3 x 2000 1000 294 2600 3894 kN. The design horizontal and moment actions are as in E2,390 kN and 1073 kNm, respectively....
How To Calculate Effective Area Of Concete In Tension Surrounding Reinforcement
Is the area of shear reinforcement within a length s is the spacing of the shear reinforcement is the breadth of the web or minimum width of the member over the effective depth is the angle between the shear reinforcement and the main steel i.e. for vertical stirrups a 90 and sin a 1 6 It should be noted that there are particular risks of large cracks occurring at sections where there are sudden changes of stress, e.g. sections where bars are curtailed areas of high bond stress, particularly at...
When A Live Load Is Considered Quasi Permanent
-A bd 0.5 total deflection -A bd 0.5 active deflection A bd 1.5 total deflection A bd 1.5 active deflection Figure 7.21. Influence of relative humidity on Slenderness Limits for Total and Active Deflections referred to 70 RH From Fig. 7.21 it can be seen that the influence of relative humidity on the slenderness ratio is important with a variation of 15 for the active deflection and 10 for total deflection from the reference value of 70 of relative humidity. The figure also shows that the...
Reinforcement Strandfor Prestressed Structures Euro Code
4 Relaxation at temperatures of the structure over 20 C will be higher than given in Figure 4.8. This may affect building structures in hot climates, power plants, etc. If necessary the producer should be asked to include relevant information in the certificate see 3.3.2 2 . 5 Short-term relaxation losses at a temperature of the structure exceeding 60 C can be 2 to 3 times those at 20 C. However, in general, heat curing, over a short period, may be considered to have no effect on long term...
Reliability differentiation Chapter Iii Reliability Differentiation
Milan Holicky1-' and Jana Markova1-1 1)Czech Technical University in Prague, Czech Republic Basic reliability elements specified in current standards for structural design commonly include failure probability related to a certain reference period T. Required reliability level of buildings and other civil engineering works is usually specified by the design (target) failure probability pd or by appropriate reliability index Jd corresponding to a specified design working life Td (for example 50...
Vacuum Filtration
We have already discussed this important technology in Chapter 5, but a review may be helpful in placing its importance to sludge processing into perspective. The vacuum filter for dewatering sludge is a drum over which is laid the filtering medium consisting of a cloth of cotton, wool, nylon, dynel, fiber glass or plastic, or a stainless steel mesh, or a double layer of stainless steel coil springs. The drum with horizontal axis is set in a tank with about one quarter of the drum submerged in...
Design procedure
a Calculate the factored load 1.6 x imposed 1.4 x dead, and then calculate the maximum factored bending moments Mx and the factored shear forces b Calculate the second moment of area required to satisfy the deflection limitations described in clause 2.6.2. For simply supported beams, use the method described in clause 4.2 b . c Determine the effective length LE from the two cases Beams with lateral restraints at their ends only The effective length LE should be obtained from Table 7 according...
Specification of the field compacted density
11.4.1 Compactive effort in the field The amount of compactive effort delivered to a point in a soil during compaction depends upon both the mass of the compacting unit and the number of times that it runs over the point, i.e. the number of passes . Obviously the greater the number of passes the greater the compactive effort but, as discussed in the previous section, this greater compactive effort will not necessarily achieve a higher dry density. The number of passes must correspond to the...
An Isochron Diagram Pore Pressure And Depth Chart
Owing to the drainage at the top and bottom of the layer the value of u will immediately fall to zero at these points. With the mathematical solution it is possible to determine u at time t for any point within the layer. If these values of pore pressures are plotted, a curve known as an isochrone can be drawn through the points Fig. 10.3b . The maximum excess pore pressure is seen to be at the centre of the layer and, for any point, the applied pressure Fig. 10.3 Variation of excess pore...
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Cosec ip sinip j
Assuming that 6 0.50' 17.5 see page 203 , substituting lt f gt ' 35 , 3 0 , 6 17.5 and -0 90 into the formula for Ka Pa 0.5Ka7H2 0.5 x 0.246 x 19 x 52 58.43 kN This value is inclined at 17.5 to the normal to the back of the wall so that the total horizontal active thrust according to Coulomb, is 58.43 x cos 17.5 55.7 kN. Note If 6 had been assumed equal to 0 the calculated value of total horizontal thrust would have been the same as that obtained by the Rankine theory of Example 6.1. Solution B...
Lateral Earth Pressure
The variation in the values of a soil's strength parameters with drainage conditions has been discussed in Chapter 3 and it is important that the reader has an understanding of this phenomenon. A soil can exhibit shear resistance in one of three ways i due entirely to friction, its cohesive intercept 0. The soil acts as a cohesionless soil, i.e. as a soil' or as a '0' soil' . ii Due entirely to cohesion, its angle of shearing resistance equals 0 . The soil acts as a cohesive soil, i.e. as a 'c...
What Are The Method Of Fixed Earth Support
Minimum depth is required and since Fp 2.0 has already been applied to the pressure distribution, When the top of a sheet pile wall is anchored, a considerable reduction in the penetration depth can be obtained. Due to this anchorage the lateral yield in the upper part of the wall is similar to the yield in a timbered trench, whereas in the lower part the yield is similar to that of a retaining wall yielding by rotation. As a result the pressure distribution on the back of an anchored sheet...
Dissipative versus lowdissipative structures
Steel buildings can be designed to be 'energy-dissipative' to a larger or smaller extent. As Clauses 6.1.2(1), also explained in Section 2.2.2.1 of this guide, this term refers to the ability of some 6.1.2(2), intentionally selected parts of the structure to safely undergo cyclic plastic deformations, and 6.1.2(4), applies to buildings designed such that the selected zones - and only those - are indeed 6.1.2(5), activated plastically. Then, the global behaviour of the building under seismic...
Dual systems
A dual system is one in which, according to the results of the analysis, between 35 and 65 of the seismic base shear is (or rather should be) resisted by frames of primary seismic beams and columns, and the rest of the seismic base shear resisted by primary seismic walls. Dual systems combine the satisfactory stiffness, force resistance and cost-effectiveness of walls with the ductility and large deformation capacity of frames, which can act as a second line of defence in case (some of) the...
Code Procedure for Seismic Design Category A
Structures determined to be in Seismic Design Category (SDC) A are required to comply only with the provisions of Section 1616.4 1 . There are five exceptions to this rule. First, detached Group R-3 dwellings in SDC A, B, and C are exempt from the general seismic provisions. Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories high with separate means of egress and their accessory structures shall comply with the International...
Consolidation settlement
This effect occurs in clays where the value of permeability prevents the initial excess pore water pressures from draining away immediately. The design loading used to calculate consolidation settlement must be consistent with this effect. A large wheel load rolling along a roadway resting on a clay will cause an immediate settlement that is in theory completely recoverable once the wheel has passed, but if the same load is applied permanently there will in addition be consolidation. Judgement...
Longitudinal reinforcement
Figure 5.16 Edge reinforcement for a slab 5.4.3.3 Shear reinforcement 1 A slab in which shear reinforcement is provided should have a depth of at least 200 mm . 2 In detailing the shear reinforcement, 5.4.2.2 applies except where modified by the following rules. Where shear reinforcement is required, this should not be less 60 of the values in Table 5.5 for beams. 3 In slabs if r 1 3 VRd2, see 4.3.2 , the shear reinforcement may consist entirely of bent-up bars or of shear assemblies. 4 The...
Deflection Limits For Cantilevers
Vertical deflection limits Table 7.2. Vertical deflection limits Beams carrying plaster or other brittle finish Other beams except purlins and sheeting rails The UK National Annex may define similar limits to those given in Table 7.2, and is likely to propose that permanent actions be taken as zero in serviceability checks, essentially reverting to the practice in BS 5950, which is to check deflections under unfactored imposed loading. In this case w and w2 would be zero, so w OI...
Basic Concepts Of Structural Reliability
1 2 Milan Holicky and Ton Vrouwenvelder 1Klokner Institute, Czech Technical University in Prague, Czech Republic 2Delft University of Technology, TNO BOUW, The Netherlands Uncertainties affecting structural performance can never be entirely eliminated and must be taken into account when designing any construction work. Various design methods and operational techniques for verification of structural reliability have been developed and worldwide accepted in the past. The most advanced operational...