Straight and curved steel I-girder bridges - Computational Analysis and Design of Bridge Structures - page 218

where:
E cmt (MPa or psi) is the effective modulus and is used to compute the
modulus ratio between concrete and steel
γ c (kg/m 3 or lb/ft 3 ) is the unit weight of concrete

7.3 2d and 3d IlluStrated exaMPle
of a haunChed Steel I-gIrder
BrIdge—Md140 BrIdge, Maryland

Bridge No. 6032 is on MD140 over Maryland Midland Railroad, MD27,
and West Branch in Carroll County, Maryland. It was originally built in
1952. However, due to severe deterioration over years, the superstruc-
tures of this bridge including all girders and deck were rebuilt in 2005.
Description of the structure is given in Table 7.1. The rebuilt of this bridge
was partially funded by the Federal Highway Administration's Innovative
Bridge Research & Construction (FHWA-IBRC) Program as an application
of a high-performance steel (HPS) bridge.
In the design process, AASHTO 2D line girder method was adopted. As
mentioned in Section 7.2.1, for the line girder approximate method, certain
conditions have to be met, such as

Table 7.1 Description of th e MD140 Bridge structure
Item Description

Structure identification Bridge #06032

Location MD140 over MD27—in Carroll County

Structure type 15-Steel-girder bridge

Span length(s)

148 ′ -152 ′ (45.11-46.33 m) two-span bridge

Girder web depth Varied from 45 ″ to 81 ″ (1143-2057 mm)

Roadway width 61 ′ (18.6 m) clear roadway width with 5 ′ (1.5 m) sidewalk

Northbound
6 ′ (1.8 m) median and 50 ′ (15.2 m) clear roadway width
with 5 ′ (1.5 m) sidewalk Southbound

Structure width 130 ′ (39.6 m) out-to-out superstructure

Cross-frame type K-type intermediate cross frames; channel-end diaphragms

Girder spacing 5 @ 10 ′ -0 ″ (3.05 m), 2 @ 7 ′ -3 ″ (2.21 m), median 5 ′ -0 ″

(1.52 m), 2 @ 7 ′ -3 ″ (2.21 m), 4 @ 9 ′ -9 ″ (2.97 m)

Structural steel F y = 70 ksi (483 MPa)

Abutments Concrete abutment

Construction phases Three phases; (1) girders 6-11, (2) girders 1-5, (3) girders

12-15

Pouring sequence Pouring sequence nos. 1-3 for phase 1, sequence nos. 4-6

for phase 2, sequence no. 7 for phase 2 closure, sequence
nos. 8-10 for phase 3, sequence no. 11 for phase 3 closure