BRACE2 – Meloland Overpass, El Centro California

MATERIAL PROPERTIES

Specified Properties

The as-built drawings supplied for the structure indicate that its design is in accordance with an AASHTO specification dated 1965. The following properties are specified on drawing number 58215-3 of this document, which are understood to correspond to an allowable strength design approach:

\[ \begin{aligned} f_s &= 24,000 psi \\ f^{\prime}_c &= 1,300 psi \\ \end{aligned} \]

\[ \begin{aligned} f_s &= 20,000 psi \\ f^{\prime}_c &= 1,200 psi \\ \end{aligned} \]

Effective Properties

The expected compressive strength of concrete, \(f^\prime_{ce}\), is taken at the minimum of \(5, 000\) psi as specified in @caltrans2019seismic.

The effective yield stress of reinforcement is taken as \(68,000\) psi.

Basic properties for concrete in linear members are computed according to table 3.3.6-1 of @caltrans2019seismic as follows:

\[ E_c = 33 w^{1.5} \sqrt{f'_{ce}} \quad G_c = \frac{E_c}{2(1 + \nu)} \]

where \(E_c\) is the elastic modulus, \(G_c\) is the shear modulus, and Poisson’s ratio, \(\nu\) is taken at \(0.2\) (equation 3.3.4-3 of @caltrans2019seismic).

The unit weight of concrete is assumed to be \(145\) pcf.

Property (units)	Value
\(E_c\quad(\text{psi})\)	\(4.074\times 10^6\)
\(G_c\quad(\text{psi})\)	\(1.698\times 10^6\)

Note: optimal elastic modulus values of \(533,520\) and \(560,314\) ksf were reported in @mosquera2009utilization and @mosquera2012rapid, respectively. These models were calibrated from a range of 460,000 - 560,000 ksf and 22,000-28,000 MPa for 2009 and 2012.