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Whats New in LEAP Bridge Steel CONNECT Edition V19? Shrinkage of the concrete. Where s is a coefficient that depends on the type of cement and equals 0.20 for high early strength cement (Class R), 0.25 for normal early strength cement (Class N), and 0.38 for slow early strength cement (Class S). A high modulus of elasticity is associated with a higher compressive strength of concrete, although the two are not directly proportional. What allowable stresses the Detensioning stresses are compared against ? Noticing that the concrete stress immediately prior to transfer is 0.0 and that the change in prestressing stress during transfer is the loss due to elastic shortening = 13.7 ksi, fcgpcan be calculated as: fcgp = 13.7/(28,500/4,200) = 2.019 ksi 2.016 ksi calculated above (difference due to rounding) Determine fcdpas defined above. This can be done by optimizing a continuous grading for the combined coarse and fine aggregates. No further . Utilizing the unit strength method, if I have concrete masonry units which have a compressive strength of 2,800 psi, 2,000 psi grout and Type S mortar, the specified compressive strength of masonry (f'm) is most nearly . (1). Where is the cube compressive strength of concrete in MPa. The static elastic modulus of concrete is defined as a chord modulus from the stress-strain curve with a first point at strain level of 0.00005 and second point at 40% of the maximum stress as follows: Figure 1 Testing setup and instrumentation for the uniaxial compressive test of a concrete cylinder. 4. 2. elastic shortening elastic shortening 1. 50x75 cgs cgs 75 75 Beam Section. kN L A sl p p 68.9 21 .3 100 0.64 P A E 0. When prestress is transferred to the member after the concrete is hardened, elastic shortening occurs. How to add/modify Height and/or # of strands for an existing Beam Section in Precast/Prestressed Girder Module? PERMISSION IS NORMALLY GRANTED WHEREVER SUFFICIENT ACKNOWLEDGEMENT IS GIVEN TO CE&CR. Product(s): LEAP CONSPAN/Precast/Prestressed Girder, Original Author: Bentley Technical Support Group. Various definitions of modulus of elasticity are available: initial tangent modulus, tangent modulus (at a specified stress level), and secant modulus (at a specified stress level), as shown in Fig. However there are ultrasonic methods which link the density to the modulus of elasticity of the concrete. A few researchers have recommended a formula that considers the effect of a wide range of aggregates and mineral admixtures. Table 3.1.2 of AS 3600:2018 gives the values of Ec calculated as per Eqn. As we can see from dimensional analysis of this relation, the elastic modulus has the same physical unit as stress because strain is dimensionless. For normal-weight concrete, Clause 19.2.2.1 of ACI 318M-19 code allows it to be taken as. An equivalent concrete column may shorten by about 175-250 mm, this increased displacement arising from the additional effects of shrinkage and creep of this material. Only when very high strength concrete is used, the type of aggregate will be known to the designer and hence can be used to predict the value of elastic modulus as per Fig.5. Initial Strain in Steel for Known Strain due to Elastic Shortening calculator uses Initial strain = Strain in concrete + Residual strain to calculate the Initial strain, The Initial Strain in Steel for Known Strain due to Elastic Shortening is the initial or immediate strain occurred in the steel or tendons due to initial prestressing force. ELASTIC SHHORTENING OF CONCRETE (ES) Concrete shortens when a prestressing force is applied. Unlike the creep of metals, it occurs at all stress levels and, within the service stress . Equation 1: f s =E c c. and the change of the stress in steel as. Elastic Shortening. From Fig. 4-5mm in a typical storey height. Each new floor is cast at a level which overrides all the shortening which has taken place beneath it. Shortening Steel Columns Only Elastic Shortening about 1.5 to 2mm/floor Concrete Columns Elastic Shortening about 0.5 to 0.8mm/ floor Creep about 1 to 2 x Elastic Shortening Shrinkage about 0.2 to 0.5 mm/ floor Overall very similar but happening at different times. At each storey height, a maximum shortening of 4 - 5 mm corresponding to deformation of about 1.4 mm/m is possible. Hence, modulus of elasticity and Poissons ratio, which are elastic constants, are not applicable. In pre-tensioning, all strands are anchored simultaneously. Solution. To measure modulus of elasticity of concrete, cylinders of . 6 shows the variation of strength and modulus of elasticity of concrete, made with different aggregates, calculated as per Eurocode 2 (Bamforth et al., 2008). McGraw-Hill Dictionary of Architecture and Construction. 6 represent the values calculated by Bamforth et al., 1997 based on aggregate E-value and concrete strength for concrete used in nuclear Power Station Structures. Short-term losses are described as follows: Anchorage set. Shortening in a single storey height is important for added elements which are not flexible, such as cladding and partitions. The secant modulus of elasticity of concrete value is more commonly used in structural design as it includes the effects of creep and other longer term processes. Hence, their E-value will have a significant effect on the E-value of concrete. 5: Modulus of Elasticity of Concrete with Different Aggregates related to the Compressive Strength of Concrete. fcgp = 14.53 MPa fpES = ( 11 - 1) (7.52) (14.53 MPa) = 49.67 MPa 2(11) Loss due to elastic shortening (ElasticShort)a = (49.67 MPa) (350.64b mm2) = 17.41 kN Total loss due to elastic. Tension is taken to be positive and compression is negative, throughout. Article 5.9.3 Page 1 of 3 10/2017 5.9.3 PRESTRESS LOSSES Elastic Losses or Gains, fpES fpES is the sum of all the losses or gains to the strand stress due to elastic shortening or extension caused by either internal (prestressing) or external (gravity) loads applied to the concrete section. Differential shortening. Elastic Shortening es ps cir ci ES =K E f /E (Eq. The modulus of elasticity of concrete is required for the estimation of the deformation of buildings and members. ADVERTISEMENTS IN CE&CR ARE PUBLISHED FOR INFORMATION OF THE SUBSCRIBERS. (15) should not be used retrospectively to justify nonconforming reference strength. As Eqn. Accurate prediction of modulus of elasticity is important in reinforced and prestressed concrete structures while calculating member deformations, elastic shortening of columns, shrinkage and creep loss as well as crack width. 12.33. High-strength concrete (HSC) will have a higher modulus of elasticity and hence will result in reduced deflection and increased tensile strength. In these applications, designers can take full advantage of the increased compressive strength of HSC to reduce the amount of steel, reduce column size (to increase usable floor space in high-rise buildings), or allow additional stories. Uniform temperature used to calculate horizontal displacement. The Youngs modulus of concrete formulas used in the spreadsheet are detailed below. 4. Export of Reactions from Conspan to Rcpier, Flared Girder -- Spacing between the girders along the Support, Flared girder bridges - Calculation of distance between center of Abutment to the center of abutment. Shrinkage. Application of Centrifugal force in Leap Conspan, Application of concentrated loads to lane loads, Calculation of cracked section properties, Calculation of negative moment for Permit Vehicles (PV), Camber and Deflection -- Diaphragm load as part of Total self-weight of the beam. Strain in Concrete due to Elastic Shortening [c] Copy Steps Formula Reset Strain in Concrete due to Elastic Shortening Solution STEP 0: Pre-Calculation Summary Formula Used Strain in concrete = Initial strain-Residual strain c = pi-po This formula uses 3 Variables Variables Used Modulus of elasticity may be determined using an extensometer attached to the compression test specimen as described in IS 516:1959 or ASTM-C469M-14 (Subramanian, 2019). In addition, the pile shortening due to the end-bearing load component is added to the top settlements by treating the pile as an elastic column. Search results for 'elastic shortening of concrete' Topics : Concrete technology, Cements, Modern cements history, Portland cement manufacturing, Portland cement wet process manufacturing, Portland cement dry process manufacturing, Cement chemical composition, Cements hydration, Heat of hydration, Calcium silicate hydrates, Calcium hydroxide, calcium aluminate hydrates, hydrated cements . To find compressive strength of concrete, cubes of size 150 mm has been prepared. Therefore, there was an increase in the Dischinger elastic shortening losses at 104 and 730 days (2 years) for the exterior girders. Where, is the mean value of the in-situ compressive strength of concrete at the relevant age. They also suggest adopting the following while designing structures: Noguchi and Tomosawa, 1995 and Noguchi, et al., 2009 proposed the following equation which applies to a wide range of aggregates and mineral admixtures used in concrete. Technical Report 67 considers the shortening of a range of columns (different concrete strengths and reinforcement percentages) and concludes that a maximum shortening of 1.4mm/m is possible, i.e. Specifying the largest practical maximum size of aggregate and a suitable grading may result in higher content of coarse aggregate in a concrete mixture. However, for the sake of simplicity, they are used in the analysis and design of concrete structures, assuming elastic behavior. Often this is the case with concrete as the strength and modulus of elasticity of the concrete usually correlate quite well, but this is not always the case. When lightweight aggregates are used, the CEB-FIP equation was found to overestimates the modulus, and the calculated values decreased when coarse aggregate such as crushed quartzite, crushed limestone, and calcined bauxite was used (Vakhshouri and Nejadi, 2019). Each increment of load causes an initial elastic strain which increases over time by a process known as creep. This is generally acceptable as the correlations are fairly accurate and the Youngs modulus of concrete does not usually have a large impact on the design so long as it remains within normal parameters. It is obvious from Hooke's law, that if we have a change in strain, there will be a change in the stress. 4 yo 50x75 cgs 75 Beam Section cgs 75 Solution Method 1: Using net section of concrete Ac = Ag Aduct = 200 x300 50 x75 . Young's Modulus in N/mm2 E. 3. Where Ec(t) is the effective Youngs modulus at the age of t days; (t) is the compensating factor taking account of creep during concrete temperature increasing for up to 3 days =0.73, for after 5 days =1.0 (linear interpolation can be used from 3 to 5 days) and (t) is the estimated compressive strength of concrete at t days. 2. Hi sir i was looking for (calculation formula) of Static modulus of elasticity of concrete in compression test method is, ASTM C 469 - 94. 6. The test set-up for measuring the modulus of elasticity is shown in Fig. The formulae specified in different codes are reviewed. Generally it is differential shortening which is important, particularly between columns, which are generally heavily loaded, and core walls, which are usually more lightly loaded. 5. Slip from anchorage setting is a user-defined parameter. Moreover, the effects of creep and shrinkage will make the concrete behave in a non-linear manner. Note this is also sometimes referred to as the Youngs modulus of concrete after the scientist Thomas Young who popularized the concept of a linear elastic relationship between stress and strain for solid materials at low stresses. In a structural member, a decrease in the length (under an imposed load) which is linearly proportional to the load. Ans: fT = 4.829 MPa, fB = +23.913 MPa 200 300 Fig. 2.3Loss Due to Elastic Shortening (ES) Loss of prestress due to elastic shortening of the concrete should be calculated based on the modulus of elasticity of the concrete at the time the prestress force is applied. The ACI committee report on HSC (ACI 363R-92) provides the following equation for modulus of elasticity, which has also been adopted by NZS 3101- Part 1:2006. That is unless the strength of the stiffer materials is increased in proportion with the modulus of elasticity. Creep strain = Ce x Elastic strain Elastic strain = (fc/Ec) fe is the stress in concrete at the level of steel. Export and Import of reactions from Conspan to RCPier. Shrinkage starts immediately the early thermal contraction cycle has passed, and then continues at a decreasing rate. 5. can somebody tell me how to calculate the elastic shortening of these piles. The value of Ecd is generally 20%, 30%, and 40% higher than the secant modulus for high, medium- and low-strength concretes, respectively (Mehta and Monteiro 2006). The author wishes to thank Dr. Ahmad Fayeq Ghowsi, Post-Doctoral Fellow at IIT, Delhi, for his help in making the drawings. the shortening, and then describe options for documenting and communicating information to contractor. 7 it is also seen that the values calculated as per Euro code 2 expression (Eqn. Previously Published in Proceedings, Texas Section ASCE Fall Meeting, September 29-August 2, 2004, Houston, Texas Comparison of Methods of Estimating Prestress Losses for Bridge Girders by Scott Walton, M.S.C.E., E.I.T.1 and Timothy E. Bradberry, M.S.E., P.E.2 ABSTRACT A new method for estimating prestress losses has been published in NCHRP Report 496, where c is the unit weight of concrete (varies between 1440 kg/m3 and 2560 kg/m3). Fig. 3. QUESTION: Where can the user find Elastic shortening information in Conspan output ? Is there a hand calculation example for rating? It should be noted that higher modulus of elasticity of the concrete is often not really desirable in a concrete member as higher stiffness materials will attract greater stress and therefore fail sooner than more elastic materials. Hence, the initial tangent modulus is considered to be a measure of the dynamic modulus of elasticity (Neville and Brooks 2010). The equation for elastic modulus in the Russian SP 52-101-2003 has a different format as shown below: High-strength concrete (HSC) is often used in the columns of high-rise buildings, long-span bridges, parking garages, and offshore structures, where improved density, lower permeability, and increased resistance to freeze-thaw and corrosion are required. article. Lspan= 110.5 ft. (1,326 in.) Different national codes suggest different expressions for the determination of the modulus of elasticity of concrete, to be used in the design. Modulus of elasticity, however, is affected to a lesser extent by the chemical and mineral admixtures, curing conditions, age of the concrete and the type of cement (Russian Standard SP 52-101:2003). I we have more than one tendon and the tendon are stressed in succession, the the . 7. (3), while Type II is more accordant with Eq. between interior columns and cores and shear walls on the one hand and perimeter columns on the other. Pre-tensioned Axial Members Elastic Shortening Pi P0 Length of tendon before stretching pi p0 c Elastic shortening of a pre-tensioned axial member 25 41. There's a document titled "Column Shortening in Tall Structures" by Mark Fintel, S.K. Bulk strain is the response of an object or medium to bulk stress. f'c = Compressive strength of concrete. Where = + 8 MPa, and is the cylinder compressive strength of concrete The coefficient present only in the CEB-FIP Model code has a value of 1.2 for basalt and dense limestone, 1.0 for quartzite, 0.9 for limestone, and 0.7 for sandstone aggregates. 001188 193000000 = = = . There is an increased awareness and use of lightweight concrete (LWC) in applications like elevated slab structures; bridge decks; wall, ceiling, and floor insulation; and insulation for fire protection. The Architectural Institute of Japan specifies the following equation to estimate the modulus of elasticity of concrete 8. More details about the dynamic modulus of elasticity may be found from Popovics, 2008. In the US there is a standard test procedure detailed in ASTM C469. 6: Variation of Strength and Modulus of Elasticity of Concrete with Different Aggregates. The modulus of elasticity of concrete calculations can estimate the dynamic, static and long term modulus of elasticity of concrete values. Further information on aggregate grading is included in our Grading of Aggregates in Concrete post. The modulus of elasticity is also required in seismic analysis for rational calculation of drift and deformations. 22 ksi (152 MPa) for bars. At the level of the prestressing tendons, the strain in the concrete must equal the change in the strain of the steel. The actual correlation is with the density, not the strength. C = a correction factor to allow for different modulus of elasticity of the aggregates. In the new Enhanced report Viewer window under Span 1 , Beam 1 option--> Straight Option, the user should be able to get the Beam Shortening (PL/AE) information in "inches" . In this paper, Eq. Stress in concrete due to prestress is computed by elastic theory, which assumes that there is a linear relationship between the stress and the strain. Elongation in mm e. 4. As per Eurocode 2, the value of elastic modulus Ecm as computed by using equation (4), should be reduced for concrete with limestone and sandstone aggregates by 10% and 30% respectively. The strength of concrete is dependent on the relative proportion and modulus of elasticity of the aggregate. Ans: fT = 4.829 MPa, fB = +23.913 MPa 200 Fig. For both normal-strength (NSC) and high-strength (HSC) concrete, the Comit Euro-International du Bton and the Fdration Internationale de la Prcontrainte (CEB-FIP) Model Code and Euro code 2 suggest that the approximate value of secant modulus Ecm of concrete with quartzite aggregates can be obtained from the mean compressive strength as below. Relaxation of the prestressing steel. Positive bending about a horizontal axis causes tension in the bottom . Method 1: Using net section of concrete . For example, roads and pavements subject to repeated load cycles from vehicles rather than static loads should use the initial tangent value or the dynamic modulus of elasticity of the concrete. As per clause 8.6.2.2 of the Canadian code, the modulus of elasticity, Ec for concrete with c between 1500 and 2500 kg/m3 may be taken as, The Australian code AS 3600:2018, clause 3.1.2 specifies that the modulus of elasticity be taken as below noting that this value may have a range of 20%. 2. Can Live Load reactions be separated into truck and lane loads. AASHTO LFD STANDARD CODE -- Shear Resistance Ratio calculation, Adjacent Box Beam design with super elevation. fpES = N - 1 Ep fcgp (5.9.5.2.3b-1) 2N Eci. The dynamic modulus of elasticity of concrete, Ecd can be determined by the non-destructive electro-dynamic method, by measuring the natural frequency of the fundamental mode of longitudinal vibration of concrete prisms, as described in IS 516:1959. (1) and (2) are used for calculating These can however overestimate the Youngs modulus of concrete, sometimes by as much as 30% - 50% higher. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features Press Copyright Contact us Creators . 3: Various Definitions of Modulus of Elasticity of Concrete. Moreover, the US code value is 16% less than the value specified by the Indian code. Fortime dependent losses Conspan does not provide the length information , user has to calculate it manually. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. This spreadsheet can be purchased below for only 5. When there is sustained load, however, the stress-strain curve will become nonlinear, even at relatively low stresses, due to inelastic creep. Modified Young's Modulus in (as per TC) N/ mm2 ME. Loss due to Creep in steel (Relaxation of steel) When the stresses in steel is more than half of its yield stress there is creep in steel also. It is seen that several codes consider only the strength of concrete to evaluate the elastic modulus, though a few consider the density of concrete, as well. Concrete is not an elastic material, that is, it will not recover its original shape on unloading. The modulus of elasticity of concrete is required for the estimation of the deformation of buildings and members. This is shown below with fcm = the characteristic cube strength (fck) + 8. Thus is the shortening in the member due to Fi at the level of steel ( It is assumed that the change in strain in the tendon is equal to the strain in concrete (c) at the level of the tendon due to the prestressing force. LWC normally has an in-place density of 800 to 2240 kg/m3. Compute the stresses in the concrete at transfer. This causes the stress loss in the tendon installed prior to this. READERS ARE ADVISED TO THEMSELVES VERIFY THE DETAILS. = = The results of the above equation and also Eq. (2) Elastic shortening losses Because all tendons will be simultaneously tensioned the elastic shortening of concrete will not affect tendons since it will be taking place at the same time as tensioning and no loss of prestress force will take place. 2. 4.1. CE&CR DOES NOT AUTHENTICATE, ENDORSE OR GUARANTEE ANY OF THE PRODUCTS OR SERVICES OR CLAIMS MADE BY THE ADVERTISERS. It is used to analyze the concretes behavior under load, including deflections. 7. Thus, elastic shortening of concrete is caused by full prestress force, and all the tendons should have similar degree of loss due to the . 2) where Kes = 1.0 for pretensioned members. LARS | LEAP | OpenBridge | OpenTunnel | RM, LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki, Enhancements and corrections in LEAP Bridge Concrete version 22.00.02.19 (part of Open Bridge Designer version 10.11.00.40 (September 2022). Hence: 2 p p jack jack t c g g g A E P P e M e P E A I I = + + The concrete never feels the full jacking force since the strands shorten as the concrete strains. In prestressed concrete, the shortening of a member which occurs immediately on application of forces induced by prestressing. -LEAP Bridge Concrete Main page + CIP RC/PT Girder. The modulus of elasticity of concrete is difficult to measure directly due to difficulties in accurately measuring the tiny strains involved. This assumption is called strain compatibility between concrete and steel). Vertical Shear -- Calculation of Mmax value. Increasing the water-cement ratio will reduce the value of modulus of elasticity, similar to its effect on the compressive strength of concrete. We can also see from Equation 12.33 that when an object is characterized by a large value of elastic modulus, the effect of stress is small. The formula for just the transfer length part is 1/3*fse* (strand diameter) According to PCI, the definition of fse is as follows (pg. Subscribe to our eNewsletter. The value of fc(t) can be determined using the following expression given in the Euro code 2. in prestressed concrete, the shortening of a member that occurs immediately on the application of forces induced by prestressing. It is important for the Indian code, IS 456, to specify a formula, which considers the effect of as many factors as possible, in the evaluation of the elastic modulus of concrete, so that the deformations of structures are predicted accurately. Euro code 2 also warns that Eqn. As the elasticity is difficult to measure, for design a modulus of elasticity of concrete formula is used which correlates the modulus of elasticity of the concrete with the concretes compressive strength. Accurate prediction of modulus of elasticity is important in reinforced and pre-stressed concrete structures while calculating member deformations, elastic shortening of columns, shrinkage and creep loss as well as crack width. (1) of ACI 318-19, with the experimental values of several researchers, are compared in Fig. The elastic shortening, installation and interaction of the concrete and steel tendons hastens the loss of tension in the tendons. Concrete Bookshop - Members receive 40% discount on Concrete Society publications, Axial shortening of concrete columns in high-rise buildings, TR67 Movement, restraint and cracking in concrete structures. For basalt aggregates, the value should be increased by 20%. The use of dense aggregates such as basalt than limestone, which in turn results in a higher modulus than lightweight aggregates. Vertical Shortening The main cause of vertical shortening in tall buildings is the compression of vertical elements under the load they carry. Elastic Shortening Similarly to prestressed concrete, post-tensioned concrete loses tension in the tendons over time. This loss is not uniformly distributed along the length of . How to import a beam section from a file to library? This is known as elastic shortening. Elastic Shortening 40. Construction sequence. 5. Though not mentioned in the Eurocode 2, equation (4) for concrete with quartzite aggregates is also valid for concrete with siliceous aggregates (Bamforth, et al., 2008). fcgp = sum of concrete stresses at the center of gravity of prestressing . As the tendons that are bonded to the adjacent concrete simultaneously shorten, they lose part of the prestressing force that they carry. (11) provides better correlation, especially for high-strength concrete. Creep of the concrete. Here, the elastic modulus is called the bulk modulus. In V13.00.00.68 the Double tandem is not selected as the default truck . This value does not include the effects of creep, yield or other longer term effects which are not important for repeated dynamic loads such as those experienced on concrete roads. Fig. Substituting k1 = 1.0 and k2 = 1.0 and simplifying we get . Fig.4: Modulus of Elasticity Versus Concrete Strength, Clause 3.1.2 of the Australian code AS 3600:2018, suggest the following equation, noting that this value may have a range of 20%. Elastic shortening; Friction loss due to length (wobble) and curvature effects; Long-term losses: Concrete creep; Concrete shrinkage; Steel relaxation; Short-term losses. It is traditionally produced using lightweight aggregates such as expanded shale or clay, vermiculite, pumice, or scoria; however, it can be also produced using foaming technologies and polystyrene beads. However, according to The Concrete Society (UK), column shortening is not significant in reinforced concrete buildings less than 10 - 15 storeys. (2009) (Eqn. For example, in an 80-story steel structure, the total elastic shortening of the columns maybe as high as 7 to 10in, (180to 255 mm) due to the high design stress levels of modern high strength steels. The following expression was proposed for the static modulus of elasticity of high-strength concrete according to the Draft Australian Standard DR05252 C469 at 40% of the ultimate load: Ec = 2822 (f ) i c t + 14110 (MPa) (3) For this equation concrete cylinder strength at 28 days should be between 21 and 83 MPa. ANSWER: The modulus of elasticity is dependent on the compressive strength of concrete, properties of the coarse aggregates, the proportion of the aggregates in the concrete, quality of cement paste and addition of mineral admixtures (Zhang and Gjvorv, 1991, Neville, 1996). Saved Strand Pattern, Stirrup patterns, Rebar in Beam, Skew Correction Factor - Thickness of Slab, Skewed bridge - Correction factor due to load distribution factors, Skewed Bridge and shear in the exterior beams, Some deflections are zero after copying the strand pattern to another beam. Such concretes tend to have a higher modulus of elasticity, provided the aggregates used have a high modulus of elasticity (Crouch et al., 2007). Wc is unit weight of concrete. Gosh and Hal Lyengar.

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