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En jämförelse av Eurokod och Boverkets konstruktionsregler

Hammar, Henrik (2011)
Programmes in Helesingborg
Abstract
On January 1, 2011 the new structural design rules (Eurocode) became valid in Sweden; these rules are common to the entire European Union. The reason for the introduction of the Eurocode is to try and eliminate trade barriers between member states. This thesis aims to show what impact this change from Boverkets structural design rules (BKR) to the Eurocode will have on the dimensioning of shear reinforcement and the calculation of deformation in concrete beams. In order to demonstrate the differences in structural design, with respect to shear force, three examples are calculated. Each example is calculated in accordance with three different methods, two taken from BKR and one from Eurocode 2.
Table 2.2 summarizes the calculation results... (More)
On January 1, 2011 the new structural design rules (Eurocode) became valid in Sweden; these rules are common to the entire European Union. The reason for the introduction of the Eurocode is to try and eliminate trade barriers between member states. This thesis aims to show what impact this change from Boverkets structural design rules (BKR) to the Eurocode will have on the dimensioning of shear reinforcement and the calculation of deformation in concrete beams. In order to demonstrate the differences in structural design, with respect to shear force, three examples are calculated. Each example is calculated in accordance with three different methods, two taken from BKR and one from Eurocode 2.
Table 2.2 summarizes the calculation results of the concrete shear capacity (V_c, V_Rdc, V_(Rd,c)), center distance (s) between and the diameter (Ø) of the shear reinforcement. The results in Table 2.2 show that the concrete shear capacity is generally a bit higher with Eurocode then with BKR. This is because the Eurocode’s characteristic strength values for concrete and steel is higher than the corresponding value given in the BKR. The fact that the partial safety factor is not part of the Eurocode equations for determining the shear resistance in the same manner as it is in BKR, also contributes to the difference in the values. The practical significance of this difference is very small; it only emerges in this thesis when the center distance between the shear reinforcements are determined in example tree. The distance is larger according to Eurocode compared to BKR.
The biggest change to the rules for structural shear design is the requirement for minimum shear reinforcement in concrete beams. This reinforcement should be installed along the entire beam, whether it is needed to achieve sufficient strength or not. Taking into account the requirement of minimum reinforcement, table 2.4 is obtained and presents the final selections of reinforcement rebar for the different calculation methods. Compared to table 2.2 the center distance decreases between the shear reinforcement in Eurocode example one and two, when the requirement for minimum shear reinforcement is taken in to account. The Eurocode’s introduction off this requirement has increased the amount of shear reinforcement rebar required in the structural design of concrete beams, leading to increased material and installation costs. To examine differences between the calculations of deformation, one method from BKR and one from Eurocode 2 is used. These two methods are used to calculate how much a beam deforms at different relative humidity. The results of these calculations are presented in Table 3.3. The relative humidity’s are; 50% in example one and 80 % and 95 % in example two and three. Table 3.3 shows that the results do not vary very much between the two calculation methodologies, worth noting are that the deflection does not change between example two and three when calculated with the method from Eurocode. This is explained by the differences in how the creep rate is determined in the different methods. According to BKR the creep rate is determined by consulting a table with three different levels of relative humidity whilst Eurocode 2 makes use of two charts and only two levels of relative humidity (50 % and 80 %).
Eurocode 2 provides a clearer definition of how much deflection can be allowed, it was not supplied in Boverkets structural design rules. The new limits are L/250 for beams, slabs or consoles that are subjected to quasi permanent load and L/500 for deformations that can cause damage to adjacent structures during quasi permanent load. (Less)
Please use this url to cite or link to this publication:
@misc{1898141,
  abstract     = {On January 1, 2011 the new structural design rules (Eurocode) became valid in Sweden; these rules are common to the entire European Union. The reason for the introduction of the Eurocode is to try and eliminate trade barriers between member states. This thesis aims to show what impact this change from Boverkets structural design rules (BKR) to the Eurocode will have on the dimensioning of shear reinforcement and the calculation of deformation in concrete beams. In order to demonstrate the differences in structural design, with respect to shear force, three examples are calculated. Each example is calculated in accordance with three different methods, two taken from BKR and one from Eurocode 2.
Table 2.2 summarizes the calculation results of the concrete shear capacity (V_c, V_Rdc, V_(Rd,c)), center distance (s) between and the diameter (Ø) of the shear reinforcement. The results in Table 2.2 show that the concrete shear capacity is generally a bit higher with Eurocode then with BKR. This is because the Eurocode’s characteristic strength values for concrete and steel is higher than the corresponding value given in the BKR. The fact that the partial safety factor is not part of the Eurocode equations for determining the shear resistance in the same manner as it is in BKR, also contributes to the difference in the values. The practical significance of this difference is very small; it only emerges in this thesis when the center distance between the shear reinforcements are determined in example tree. The distance is larger according to Eurocode compared to BKR.
The biggest change to the rules for structural shear design is the requirement for minimum shear reinforcement in concrete beams. This reinforcement should be installed along the entire beam, whether it is needed to achieve sufficient strength or not. Taking into account the requirement of minimum reinforcement, table 2.4 is obtained and presents the final selections of reinforcement rebar for the different calculation methods. Compared to table 2.2 the center distance decreases between the shear reinforcement in Eurocode example one and two, when the requirement for minimum shear reinforcement is taken in to account. The Eurocode’s introduction off this requirement has increased the amount of shear reinforcement rebar required in the structural design of concrete beams, leading to increased material and installation costs. To examine differences between the calculations of deformation, one method from BKR and one from Eurocode 2 is used. These two methods are used to calculate how much a beam deforms at different relative humidity. The results of these calculations are presented in Table 3.3. The relative humidity’s are; 50% in example one and 80 % and 95 % in example two and three. Table 3.3 shows that the results do not vary very much between the two calculation methodologies, worth noting are that the deflection does not change between example two and three when calculated with the method from Eurocode. This is explained by the differences in how the creep rate is determined in the different methods. According to BKR the creep rate is determined by consulting a table with three different levels of relative humidity whilst Eurocode 2 makes use of two charts and only two levels of relative humidity (50 % and 80 %).
Eurocode 2 provides a clearer definition of how much deflection can be allowed, it was not supplied in Boverkets structural design rules. The new limits are L/250 for beams, slabs or consoles that are subjected to quasi permanent load and L/500 for deformations that can cause damage to adjacent structures during quasi permanent load.},
  author       = {Hammar, Henrik},
  keyword      = {betong tvärkraftsarmering deformation eurokod boverkets konstruktionsregler concrete shear reinforcement deformation eurocode boverkets structural design rules},
  language     = {swe},
  note         = {Student Paper},
  title        = {En jämförelse av Eurokod och Boverkets konstruktionsregler},
  year         = {2011},
}