The seminar covered bridge design parameters, including types of bridges, construction methods, and design philosophies. Key topics included classifications of bridges based on materials, usage, and design systems, as well as necessary design requirements and aesthetics. Additionally, the document outlined relevant codes and specifications that guide the construction and seismic design of bridges in the Philippines.

1. BRIDGE DESIGN
PARAMETERS
SEMINAR: CONSTRUCTION METHODS AND TECHNIQUES FOR BRIDGES
DATE : September 10, 2019
DPWH Standard Specifications on Bridges

2. Outline:
Part 1. Introduction to Bridge Engineering
Part 2. Design Philosophies & Parameters

3. Part 1: Introduction to
Bridge Engineering

4. Sample General Elevation Plan

6. Sample General Plan

7. Sample General Elevation Plan

8. What is a Bridge?
A structure built to span physical obstacle such as a body of water,
valley, or road, for the purpose of providing passage over the
obstacle.
A structure carrying a road over a waterway, road or other
feature, with a clear span over 3.00 meters along the centerline
between the inside faces of supports.
A bridge may have an independent deck supported on separate
piers and abutments, or may have a deck constructed integral
with supports
(Ref:DGCS 2015)

9. Bridge Superstructure
Bridge Alignment
 A Normal Bridge is a structure where the superstructure is perpendicular to
the substructure.

10. Bridge Superstructure
Bridge Alignment
 A Skew Bridge is a structure where the superstructure is not perpendicular
to the substructure. The skew angle is the deviation of the substructure
centerlines and reference lines from the perpendicular lines to the bridge
axis.
θ

11. Bridge Superstructure
Bridge Alignment
 A Curved Bridge is a structure or portion of the structure that follows a
horizontal or vertical curve alignment.

12. Types / Classification of Bridges
According to Materials used for Main Structural Members
 Timber Bridge
 Concrete Bridge

13. Types / Classification of Bridges
According to Materials used for Main Structural Members
 Prestressed Concrete Bridge
 Steel Bridge

14. Types / Classification of Bridges
According to Usage
 Temporary – a bridge with a short life span due to
deterioration and/or design limitations, including:
 Timber trestle bridge that normally requires
members to be replaced after three years.
 Bailey bridges not designed in accordance with a
Bridge Code and subject to early fatigue failure,
subject to the number of load cycles.

15. Types / Classification of Bridges
According to Usage
 Permanent
 A bridge with a design life of fifty years and usually
of concrete or steel construction.

16. Types / Classification of Bridges
According to System of Design
 Simple Spans
 Consists of separate beams for each span, supported on
bearings that allow rotation of the girders at each end
under loads.
 Continuous Spans
 Superstructure is made continuous over one or more
supports.

17. Types / Classification of Bridges
According to System of Design
 Cantilever Bridge
 Bridge built using structures that project horizontally into
space, supported at only one end.

18. Types / Classification of Bridges
According to System of Design
 Arch Bridge
 Bridge with abutments at each end and a supporting
structure shaped as a curved arch.

19. Types / Classification of Bridges
According to System of Design
 Suspension Bridge
 Type of bridge in which the roadway is hung below two
or more suspension cables on vertical suspenders.

20. Types / Classification of Bridges
According to System of Design
 Cable Stayed Bridge
 One or more towers from which cables support the
bridge deck.
Harp Fan

21. Types of Bridges (Philippines)
Deck Girder Bridges
 Reinforced Concrete Deck Girders (RCDG)

22. Types of Bridges (Philippines)
Deck Girder Bridges
 Prestressed Concrete Girders (PSCG)

23. Types of Bridges (Philippines)
Deck Girder Bridges
 Prestressed Concrete Girders (PSCG)
 Standard AASHTO I-Girders
305
102
76
279
127
127
711
406
152
305
152
76
381
152
152
914
152
457
406
178
114
483
191
178
1143
559
178
508
203
152
584
229
203
1372
660
203
1067
127
76
102
1067
254
203
203
1829
102
660
TYPE I TYPE II TYPE III TYPE IV TYPE V

24. Types of Bridges (Philippines)
Deck Girder Bridges
 Steel Girders

25. Clear Width of Bridges
Minimum Roadway Width
DGCS 1982 Updated DGCS
1 Lane 4.00 m 4.00 m
2 Lanes (rural) 6.70 m 7.32 m
2 Lanes (urban) 7.30 m 7.32 m
Farm-to-Market Roads - 5.60 m
More than 2 lanes variable Refer to Highway Design
Requirements

26. Number of Girders

27. Parts of a Bridge
1. Superstructure
1. Deck Slab
2. Girder
3. Diaphragm (End & Intermediate)
4. Post & Railing
5. Sidewalk
6. Expansion Joint
7. Bearing
2. Substructure
1. Abutment
2. Pier
 Coping
 Foundation (Column, Wall, Bored Pile, RC Pile, Isolated Footing, etc)
 Wingwall
 Approach Slab

28. Parts of a Bridge
Superstructure
SIDEWALK
INTERIOR SLAB FUTURE WEARING SURFACE
POST
RAILING
EXTERIOR SLAB
DIAPHRAGM
GIRDER
HAUNCH

29. RAILING
SIDEWALK
BRIDGE DECK
EXPANSION DAM
APPROACH
SLAB
Parts of a Bridge
POST

30. GIRDER
INTERMEDIATE
DIAPHRAGM
END DIAPHRAGM
Parts of a Bridge

31. EXPANSION
BEARING
ELASTOMERIC
BEARING PAD
Parts of a Bridge

32. Bridge Substructure
1. Abutment
Support the ends of a bridge or extreme end of a multi-span
superstructure and which usually retain or support the road approach
embankments. Abutments normally support wing walls to retain the
approach embankments.
2. Piers
Transmit the load of the superstructure to the supporting ground
and acts as intermediate supports between abutments. The piers may be
subject to stream, collision and impact loads.

33. Parts of a Bridge
Substructure - Abutment
WINGWALL BACKWALL
COPING
STEM COLUMN
APPROACH
SLAB
RISER
FOOTING
PILE CAP
PILES
WALL

34. Parts of a Bridge
Substructure - Pier
RISER
PEDESTAL COPING
COLUMN
WALL
FOOTING
PILES
PILE CAP

35. GIRDER
COPING
BEAM
COLUMN
SHAFT
BOREDPILE
Parts of a Bridge

36. GIRDER
COPING
POST,
RAILING, &
SIDEWALK
COLUMN
SHAFT
BORED PILE WINGWALL
Approach
Railing
SLOPE
PROTECTION
Parts of a Bridge

37. Steel Girder Bridge

38. Post-Tensioning of the Girder

39. Part 2: Design Philosophies &
Parameters

40. Reference Codes
BSDS 2013
DGCS 2015
AASHTO 2012
DPWH
BLUEBOOK 2013

41. DPWH Bridge Design Specifications
 Covers design for construction,
alteration, repair, and
retrofitting highway bridges and
related highway structures
 Earthquake effects shall be in
accordance with BSDS
 Covers mainly seismic design of
bridges based on LRFD seismic
design method
 Use of localized seismic
response acceleration contour
map coefficients

42. Governing Laws and Department Memorandum
Department Order No. 75 series of 1992
“DPWH ADVISORY FOR SEISMIC DESIGN OF BRIDGES”
“The basic philosophy is for the bridge to resist
small to moderate earthquakes in the elastic
range without significant damage. In case of large
earthquakes, a bridge may suffer damage but this
should not cause collapse of all or any of its parts
and such damage should readily be detectible and
accessible for inspection and repair.”

43. Governing Laws and Department Memorandum
Department Order No. 180 series of 2015
“LRFD BRIDGE SEISMIC DESIGN SPECIFICATION
1ST
EDITION, 2013”
The DPWH LRFD Bridge Seismic Design
Specifications (BSDS) has been prepared to
address the issue in the reliability of our transport
infrastructures, such as bridges, in times of
natural disasters. The destructive effects on public
and private infrastructure of recent large-scale
earthquakes demonstrate the need to update our
design guidelines.

44. Governing Laws and Department Memorandum
Department Order No. 45 series of 2016
Load and Resistance Factor Design (LRFD) Bridge Seismic Design
Specifications 1st
Edition 2013
“A one-year transition period is given for the adaptation and familiarization
on the new guidelines, criteria and specifications during which bridge
engineers have a choice of two standards:
1. Load Factor Design (present design method)
2. Load and Resistance Factor Design (DGCS Vol. 5, BSDS)
After this transition period, use of DGCS 2015 and BSDS is mandatory.”

45. Governing Laws and Department Memorandum
- RA 9184 for Memorandum Circular No. 16 series of 1994
- Conduct of Soil Analysis and Boring Tests of the Project Sites before
undertaking Design, Preparing POW and Cost Estimates and Bidding of
Government Infrastructure Projects
- Headquarters Philippines Coast Guard (HPCG) / CG-8 Memorandum Circular
No. 01-14, April 16, 2014
- Navigational Clearance for Road Bridges and Other Structures and
Navigable Inland Waters

46. Codes and Other References
DGCS 1982 Updated DGCS
Standard Specifications for Highway
Bridges, adopted by the American
Association of State Highway and
Transportation Officials (AASHTO) 1977
American Association of State Highway
and Transportation Officials (AASHTO)
2012, LRFD Bridge Design Specification
DPWH Standard Specifications Highways
and Bridges, Revised 1972 or latest
edition
DPWH Standard Specifications for
Highways, Bridges and Airports 2013
DPWH Bridge Seismic Design
Specifications, December 2013 (JICA
Study)

47. DESIGN DATA
AVAILABLE INFORMATION RELEVANT TO THE BRIDGE PROJECT SHOULD BE
COMPILED, INCLUDING THE FOLLOWING BUT NOT LIMITED TO:
1. Topographic maps of bridge site and stream catchment area
2. Geotechnical information
3. History of any prior or existing bridges at the site, (i.e. date of construction,
performance during past floods and earthquakes)
4. Road Right of Way (RROW)

48. Topographic / Hydrographic Survey
SURVEYS SHALL ALSO OBTAIN AND DOCUMENT ALL OTHER SITE
INFORMATION RELEVANT TO DESIGN INCLUDING:
1. Topographic/hydrographic survey of river channel and flood plains
- Distance of, whichever is larger : - 5 times the width of river
- 100m / 200 m

49. For new bridge cross sections over channel length:
- 20 m intervals, 11 cross sections (5 upstream, 5 downstream, 1
centerline)

50. For existing bridges, cross sections over channel length:
- 20 m intervals, 12 cross sections ( 5 upstream, 5 downstream, 1 at each bridge face)

51. Geotechnical Investigation
SHALL BE UNDERTAKEN FOR THE DESIGN OF ALL BRIDGE FOUNDATIONS:
1. At least one borehole at the proposed location of each abutment and pier
2. For piers or abutments 30m wide, minimum of two borings
3. Additional boreholes shall be drilled when there is significant difference
between adjacent boreholes or in areas where subsurface condition is
complex
4. In case centerline is realigned, confirmatory boreholes should be conducted

52. Geotechnical Investigation
5. Borehole Depth
If foundation type has not been identified,
- Minimum depth: 30 m (ordinary soil)
3 m (sound rock)
- In case bearing layer is not yet encountered,boring shall be continued
until preferred layer is encountered and/or upon the instruction of the
geotechnical engineer
6. Tests on Borehole Samples
- Standard Penetration Test (SPT) – max interval of 1.5 m and every change in soil stratum
- Laboratory Tests

53. Geotechnical Investigation
7. Required information in GEOTECHNICAL INVESTIGATION REPORT
a. Borehole location plan (with coordinates and elevations)
b. Depth of Boreholes
c. Soil stratigraphy
d. Soil parameters
e. Allowable bearing capacity
f. Anticipated settlement
g. Rock Quality Designation (RQD)
h. Shear wave velocity
i. Liquefaction potential
j. Recommended foundation type

54. Geotechnical Investigation

55. Existing Bridge Data
INSPECTION SHALL BE CONDUCTED TO REVIEW THE HYDRAULIC PERFORMANCE
OF EXISTING BRIDGES IN TERMS OF:
1. Constriction
2. Inadequate waterway
3. Excessive backwater
4. High flood velocities under the bridge or severe scouring

56. DESIGN REQUIREMENTS
1. BRIDGE LOCATION AND ALIGNMENT
2. BRIDGE WATERWAY AND LENGTH
3. SPAN ARRANGEMENT
4. FREEBOARD
5. BRIDGE DECK DRAINAGE

57. Bridge Location and Alignment
1. River morphology -
minimize risk from river
channel movements and
determine meander belt
2. River training works –
for unstable streams/
rivers with wide active
zones
3. Bridge location –
normal to the river, along
straight channels, avoid
sharp bends (scouring
and channel shifting)
4. Alluvial fans – avoid
due to hydraulic
problems

58. Bridge Waterway and Length
1. Approximate River Width, B
B = (c) Q3/4 *
Q = discharge
c = coefficient ranging from 0.5 – 0.8,
determined considering flood plain obstruction (refer to Table 3-1 of DGCS
Volume 3 Water Projects)
2. Desirable minimum bridge span length, L
L = 20 + 0.005Q **
* Developed in a study conducted in Japan

59. Span Arrangement
1. Pier location
• To meet navigational clearance requirements
• To give minimum interference to flood flow
• To be placed parallel with direction of river current
• To avoid scour and debris blockage / constriction
2. Provision for passing debris
• Increase span length and vertical clearance
• Select proper pier type
• Provide debris deflectors

60. Clearance
DGCS 1982 Updated DGCS
1. Hydraulic Clearance / Freeboard
Rivers carrying debris : 1.5 m
Other bridges: 1.0 m
Rivers carrying debris : 1.5 m
Other bridges: 1.0 m
2. Vehicular Vertical Clearance
(above roadway)
Not less than 4.80 m plus allowance
for resurfacing
Not less than 4.88 m plus allowance of 0.15m
for future road resurfacing
3. Navigational
Permit should be taken from
Headquarters of the Philippine Coast
Guard (HPCG)
Vertical clearance = HWL + HV + K
HWL = highest water level recorded within
the area of responsibility
HV = height of vessel
K = 1.0 m allowance

61. Clearance
- additional clearance requirements not included in previous DGCS
4. Air Clearance
Height clearance permit shall be secured from the Civil Aviation Authority of
the Philippines (CAAP)
5. Underpass
Not less than 4.88 m vertical clearance for entire width (or between curbs)
6. Tunnels
Not less than 4.88 m vertical clearance (exclusive of wearing surface)
7. Through – Truss Bridge
Min. vertical clearance from roadway to overhead cross bracing: 5.3 m

62. BRIDGE AESTHETICS
• Consider appearance of bridge in terms of shape, proportion, balance,
texture, and color
• Designers must consider appearance as a major design objective along
with strength, safety, and cost.
• A new bridge should consider the role, form, and design of an existing
bridge when it is located in close proximity to that existing bridge.
• Aesthetically pleasing bridges need not be more expensive than
ordinary simple bridges. Cost and appearance need to be balanced in
the design.
• Designers should have an understanding of the natural, built, and
community context of a bridge that would influence the design (e.g.
topography, biodiversity, landscape, views to and from bridge location)

63. BRIDGE AESTHETICS
• Proportion between the depth of the superstructure and bridge spans
(Normal value: 15 – 20)
• Symmetrical bridges are generally more pleasing than other layouts
and should be adopted where possible.

64. BRIDGE AESTHETICS

65. LOAD MODIFIERS
Load modifier For strength limit state
Ductility, ηD 1.05 Non-ductile components and connections
1.00 Conventional designs and details complying to AASHTO
0.95 Additional ductility-enhancing measures specified
Redundancy, ηR 1.05 Non-redundant members
1.00 Conventional levels of redundancy
0.95 Exceptional levels of redundancy
Operational
Importance, ηI
1.05 For critical or essential bridges
1.00 For typical bridges
0.95 For relatively less important bridges
For all other limit states,
η = 1.00

66. LOAD FACTORS

67. LOAD FACTORS

68. STRENGTH LIMIT STATES

69. EXTREME EVENT LIMIT STATES

70. SERVICE LIMIT STATES

71. FATIGUE LIMIT STATES

72. DEAD LOADS
Weight of all components
of the structure,
appurtenances and
utilities attached thereto,
earth cover, wearing
surface, future overlays
and planned widening

73. DESIGN VEHICULAR LIVE LOAD
Vehicular live loading on roadways of bridges or incidental structures,
designated HL-93, and shall consist of:
• Design truck or tandem load
• Design lane load
Each design lane under consideration shall be occupied by either the
design truck or tandem, coincident with the lane load, where
applicable. The loads shall be assumed to occupy 3.0 m transversely
within a design lane.

74. DESIGN TRUCK (HL – 93)

75. DESIGN LANE LOAD
DESIGN TANDEM

76. DESIGN VEHICULAR LIVE LOAD
Vehicular live loading on roadways of bridges or incidental structures, shall be
the greater of:
35 kN 145 kN 145 kN
4.3m 4.3 – 9.1m
108 kN 108 kN
1.2
m
Uniform load of 9.34 kN/m

77. DESIGN VEHICULAR LIVE LOAD
MULTIPLE PRESENCE LIVE LOAD

78. DYNAMIC LOAD ALLOWANCE, IM
The factor to be applied to the static load, shall be
F = 1 + (IM / 100)
- shall not be applied to pedestrian loads and design lane load

79. A heavy vehicle such as truck, trailer or van operated on any road
or bridge violates the law if it:
1. Exceeds the permissible single axle load of 13,500 kg. or 13.5
metric tons.
2. Exceeds the maximum allowed gross vehicle weight as
stipulated in Republic Act 8794 (Anti-Overloading Law) and its
regulations published in 2001.

80. Maximum Allowable Gross
Vehicle Weight
(GVW) (RA No. 8794)
TRUCKS/TRAILERS DESCRIPTION
MAX. ALLOWABLE
GVW (in kgs.)
CODE 1-1*
TRUCK WITH 2 AXLES
(6 WHEELS)
16,880
CODE 1-2*
TRUCK WITH TANDEM REAR AXLE
3 AXLES (10 WHEELS)
27,250
CODE 1-3
TRUCK WITH TANDEM REAR AXLE
4 AXLES (14 WHEELS)
29,700
CODE 11-1
TRUCK SEMI-TRAILER
WITH 3 AXLES (10 WHEELS)
30,380
CODE 11-2
TRUCK SEMI-TRAILER
WITH 4 AXLES (14 WHEELS)
30,380
CODE 12-1
TRUCK SEMI-TRAILER
WITH 4 AXLES (14 WHEELS)
30,380
CODE 12-2*
TRUCK SEMI-TRAILER
WITH 5 AXLES (18 WHEELS)
37,800
CODE 11-3 TRUCK – TRAILER WITH 2 AXLES
AT MOTOR VEHICLE & 3 AXLES
AT TRAILER (18 WHEELS)
30,378
CODE 11-3 TRUCK –TRAILER WITH 2 AXLES
AT MOTOR VEHICLE & 2 AXLES
AT TRAILER (14 WHEELS)
30,378
CODE 11-12 TRUCK –TRAILER WITH 2 AXLES
AT MOTOR VEHICLE & 3 AXLES
AT TRAILER (18 WHEELS)
36,900
CODE 12-3 TRUCK –TRAILER WITH 3 AXLES
AT MOTOR VEHICLE & 3 AXLES
AT TRAILER (22 WHEELS)
41,000
CODE 12-11 TRUCK –TRAILER WITH 3 AXLES
AT MOTOR VEHICLE & 2 AXLES
AT TRAILER (18 WHEELS)
37,800

81. Seismic Design Procedure

82. Seismic Design Procedure

83. Seismic Design Detailing

84. Substructure and Foundation

85. Substructure and Foundation

86. Operational Classification of Bridges
Note: The DPWH or those
having jurisdiction shall
classify the bridge into
one of the three
operational categories

87. Seismic performance of bridges as a goal in seismic design is classified into three levels
in view of SAFETY, SERVICEABILITY and REPAIRABILITY
SAFETY - implies performance to avoid loss
of life due to collapse
or unseating of the superstructure during
an earthquake.
SERVICEABILITY - means that the bridge is capable of keeping
its bridge function
such as fundamental transportation
function, role as evacuation routes and emergency
routes for rescue.
REPAIRABILITY - denotes capability to repair seismic
damages.
Seismic Performance

88. Seismic Performance

89. Seismic
Performance

90. Seismic Hazard Map
Previous Hazard Map New Hazard Map

91. Seismic Hazard (Design Spectra)
SPECTRA COORDINATES
T Tm Csm
0 0.000 0.1872
To 0.119 0.4680
0.2-sec 0.200 0.4680
Ts 0.595 0.4680
0.646 0.4313
0.690 0.4036
0.729 0.3821
0.763 0.3651
0.792 0.3514
0.818 0.3403
0.841 0.3311
1-sec 1.000 0.2784
1.250 0.2227
1.500 0.1856
1.750 0.1591
2.000 0.1392

92. Response Modification Factor, R
 Specifications recognize that it is uneconomical to design a bridge to resist large earthquakes
elastically.
 Columns are assumed to deform inelastically, where seismic forces exceed their design level.
This is taken by dividing the elastically computed force effects by an appropriate response
modification factor, particularly to columns.
 Columns should have enough ductility to be able to deform inelastically to the deformation
caused by large earthquakes, without loss of post-yield strength.

93. Analysis Requirements

94. Railing & Post
Department Order No. 54 series of 2018
“UPDATED STANDARD PLANS FOR SINGLE SPAN BRIDGES AND ALTERNATIVE
BRIDGE RAILINGS”

95. Deck Slab
Main: Transverse Top Bars
Main: Transverse Bottom Bars
Temperature : Longitudinal Top Bars
Distribution: Longitudinal Bottom Bars
Cantilever Slab Bottom Bars
Exterior Slab
Interior Slab

96. Girder
RCDG PSCG

97. Girder PSCG – TENDON PROFILE

98. Girder
ROLLED SHAPE GIRDER
BUILT-UP GIRDER

99. Substructure
ABUTMENT (MOV.) FIXED PIER

100. Substructure – BORED PILE
WITH PERMANENT CASING
WITHOUT PERMANENT
CASING

101. THANK YOU!