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From page 31... ... This effect is evaluated for users of both the AASHTO Standard Speciﬁcations and LRFD Sectional Design Model who choose to use either of the two proposed shear design methods. Section 3.8 presents how design database was incorporated in NCHRP Process 12-50. Read the entire page →
From page 32... ... . 3.1.2 Proposed Simplified Provisions The proposed simpliﬁed provisions are given here in both ksi and psi units. Read the entire page →
From page 33... ... 3.2 CHANGE PROPOSAL 2: MODIFICATION OF LRFD SECTIONAL DESIGN MODEL (S5.8.3) The shear design provisions in the 1994 Canadian Standards Association code for the Design of Concrete Structures (6) Read the entire page →
From page 34... ... 34 Figure 21. Flowchart for use of proposed simpliﬁed provisions. Read the entire page →
From page 35... ... 35 Figure 22. Flowchart for shear design in accordance with CSA. Read the entire page →
From page 36... ... This example illustrates the shear design in the negative moment region of a beam made continuous with nonprestressed reinforcement. Example 3: Reinforced Concrete Cap Beam This design example demonstrates the shear design of a section of a non-prestressed 15-ft span cap beam supported on three circular columns of 3-ft diameter. Read the entire page →
From page 37... ... This result is to be expected as the proposed simplified provisions limit the shear strength conservatively to guard against brittle diagonal compressive failures. 37 Figure 24 presents the trends in the strength ratios for the CSA method as a function of: (a) Read the entire page →
From page 38... ... In order to obtain a range of shear design stress levels and M/V ratios at each of these sections, each member was designed for Figure 23. Comparison of simpliﬁed approach predictions and test results. Read the entire page →
From page 39... ... . This led to some shear design stress levels larger than those commonly seen in current design but are still admissible by the LRFD 39 specifications. Read the entire page →
From page 40... ... For this evaluation, the required amount of reinforcement, ρv fy, required by 5 methods (AASHTO Standard Speciﬁcations) , the LRFD Sectional Design Model (LRFD) Read the entire page →
From page 41... ... 3.6.2 AASHTO-Standard Specifications → LRFD Proposed Simplified Provisions (Modified Standard) Given that many states have not yet switched to using the LRFD Bridge Design Speciﬁcations, many designers probably will choose to use the proposed simpliﬁed provisions because they are more similar in structure to the AASHTO Standard Speciﬁcations than is the Modiﬁed LRFD Sectional Design Model (CSA Method) Read the entire page →
From page 42... ... Although evaluating the capacity of a structure is simpliﬁed by the CSA method, it is still iterative as x is a function of the angle θ. 3.6.4 LRFD Sectional Design Model → LRFD Proposed Simplified Provisions (Modified Standard) Read the entire page →
From page 43... ... 43 3.7.4 Evaluation of Change Proposals Using Design Cases Examples In order to evaluate the expected safety and economy for regions away from supports and for members not well represented in the experimental test database, it is useful to compare the required strengths of shear reinforcement for a large number of design cases by the four design methods and Response 2000. These design cases covered some design sections over the length of prestressed and non-prestressed members, simple and continuous structures, members with rectangular and I- or T-shaped cross-sections, and members designed to a different percentage of feasible ﬂexural capacity. Read the entire page →
From page 44... ... 44 TABLE 7 Comparison of required transverse reinforcement Figure 25. Selected design database. Read the entire page →
From page 45... ... The NCHRP report on Process 12-50 provides sample codes written in Visual Basic, Visual C++, and FORTRAN that developers can use to generate input data. It also presents a common viewer program that enables the developers to ﬁnd TABLE 8 Comparisons of selected design database Read the entire page →
From page 46... ... However, it was found to not contain the range in member types and shear design stress levels suitable for comparing required amounts of shear reinforcement by different design code provisions. In addition, the information in the NCHRP database was not sufficient for shear design calculations in accordance with other than AASHTO LRFD speciﬁcations. Read the entire page →

From page 31...

... This effect is evaluated for users of both the AASHTO Standard Speciﬁcations and LRFD Sectional Design Model who choose to use either of the two proposed shear design methods. Section 3.8 presents how design database was incorporated in NCHRP Process 12-50.