Attachment_J.6_Draft_Existing_Work_Plan.pdf

Data Collection Plan

DRAFT

July 20,2015

DTFH6116R00037

Attachment J.6

10/19/2016

INTRODUCTION

This document presents and describes the details of the data collection plan and schedule developed for the combined LTBP Program and Pooled-Fund study (Pooled-Fund Project Number TPF-5(283): The Influence of Vehicular Live Loads on Bridge Performance). The data collection plan presents the equipment and methods that will be used to collect truck weight and classification data at two different bridge test sites along with the corresponding bridge responses induced by the trucks crossing these bridges. The data collection plan also describes the procedures that will be employed for collecting, processing, analyzing and archiving of the measurement data recorded from each test site. The data reduction protocols developed for the LTBP Program will be implemented for the bridge monitoring data collected as part of this project.

This data collection plan was developed based on feedback received from FHWA LTBP staff and from members of the Technical Advisory Committee (TAC) assigned to the pooled-fund study and from the TRB LTBP Bridge Traffic and Truck Weights Expert Task Group (BT&T ETG) following several presentations and meetings with these groups and meetings with LTBP staff that summarized the work accomplished and findings from the previous project tasks. The TAC members provided specific recommendations to the FHWA for the data collection stage of the project following a meeting held on May 13, 2015 during which the project team outlined various truck and bridge response data collection approaches, costs and benefits. The recommendations given by the FHWA LTBP Program and the TAC are summarized as follows:

1. The truck weight and classification data collection should be accomplished at this stage using Alternative 1 and Alternative 2 that were identified during a prior project task. Alternative 1 is to use existing Weigh-in-Motion (WIM) sites operated by the States and/or the FHWA Long Term Pavement Performance Program (LTPP) located near the bridges proposed for monitoring under this project. Alternative 2 is to purchase, install and operate a new pavement WIM site near the approach to the monitored bridges. Alternative 3 – Bridge WIM and Alternative 4 – Tag & Track were not recommended for implementation with the initial stage of the data collection and monitoring program.

2. The data collection program should be initiated for two bridges identified from the seven states participating in the pooled-fund study. These bridges should include one steel structure and one prestressed concrete structure. The proposed bridges should be simple span structures with minimal or no skew.

3. These instrumentation plans developed for monitoring the bridge responses due to live loads should consider if a reduced sensor layout (not instrumenting the structure under all traffic lanes) for the prestressed concrete bridge would be adequate for the meeting the project objectives.

4. Instrumentation plan should include firm cost estimate for the instrumentation, data collection and analysis.

OVERVIEW OF THE PROPOSED BRIDGE SITES

Based on the recommended site selection criteria provided by the FHWA LTBP Program, Several candidate bridges located in the states participating in the pooled-fund project have been identified.

These bridges were either located near (within 50 miles) existing weight enforcement stations or state-owned or LTPP pavement WIM systems. The design plans and most recent bridge inspection reports were obtained and reviewed for these bridges. A prestressed concrete multibeam bridge with a cast-in-place concrete deck located in Oregon and steel multibeam bridge with a cast-in-place concrete deck located in Wisconsin were identified as possible candidate structures for this research. The two bridges are further described in the following sections. The proposed bridges would be considered “reference bridges” for the Long Term Bridge Performance (LTBP) program and would be subjected to the full range of characterization methods employed for those structures.

Prestressed Concrete Multi-Beam Bridge with Cast-in-Place Concrete Deck

The prestressed concrete bridge proposed for the initial stage of the data collection program is Bridge #0957800619516 which carries two westbound lanes of Interstate 84 (HWY 6) over County Road 1133 (Nolin Road) in Umatilla County, Oregon. The bridge was constructed in 1969 and is located approximately 31 miles west of the Emigrant Hill Weight Enforcement Station which is located at M.P.

227 (Latitude: 45.59115, Longitude: -118.5455) on westbound Interstate 84. The 2013 ADT for the bridge was 7,400 with 29% trucks.

An aerial view of the bridge is shown in Figure 1. The bridge crossing consists of three simple spans of

Type III prestressed concrete beams. The bridge has a 1620’00” right forward skew. The overall length of the bridge is 160 ft and includes two equal length end spans (Span 1 and Span 3) of 40 ft, and a center span (Span 2) with a length of 80 ft. The superstructure framing plans for the end spans consist of five equally spaced beam lines on 9.25 ft centers. The framing plan for the center span consists of six equally spaced beam lines on 7.4 ft centers. Each end span has reinforced concrete diaphragm beams at each bent and the midspan location. The center span has reinforced concrete diaphragm beams at each bent and at the approximate 1/3 and 2/3 points along the span.

This bridge deck was reconstructed in 2004 and consists of 8 in thick reinforced concrete slab. The reinforced concrete deck is composite with the prestressed beams and is continuous over the interior bents for live load. The overall width of the bridge deck is 43.5 ft and the overall roadway width is 40.95 ft measured from toe to toe of the concrete barriers. The bridge deck services 12 ft wide traffic lanes, a 10 ft wide right shoulder, and a 6 ft wide left shoulder.

Steel Multi-Beam Bridge with Cast-in-Place Concrete Deck

A steel multi-beam bridge located in Wisconsin is the second bridge proposed for the data collection program. The bridge (B37018200000000) carries two westbound lanes of State Highway 29 over County

Highway Q in Marathon County, Wisconsin. The bridge has an 1127’13” right forward skew. The bridge was constructed in 1990 and is located approximately 8.5 miles west of an existing Long Term Pavement Performance (LTPP) Program WIM Site. The LTPP WIM site is located at M.P. 189.8 on westbound State Highway 29 (Latitude: 44.850435, Longitude: -89.266719) and consists of bending plate scales and inductive loops installed in the right traffic lane. The 2010 ADT on the bridge was 5,600 with 8% trucks.

An aerial view of the bridge is shown in Figure 2. The bridge is a single span welded plate girder structure with composite concrete deck. The length of the span is 130 ft measured center to center of the bearings. The framing plan consists of five equally spaced girder lines on 9 ft centers. The end diaphragms at each abutment are constructed from steel channels and plates. There are five lines of intermediate crossframes consisting of steel angles that are spaced at 21.67 ft. The welded plate girders are constructed from 7/16 in thick by 54 in deep web plates, 12 in wide top flange plates that vary in thickness from 5/8 in to 1 7/8 in. The bottom flange plates are 20 in wide and vary in thickness from 1 in to 1 7/8 in. A photograph showing the underside of the bridge is shown in Figure 3.

The bridge deck consists of an 8 in thick reinforced concrete slab. The overall width of the bridge deck is 43 ft measured out to out. The bridge roadway width is 40 ft and services 12 ft wide traffic lanes, a 10 ft wide right shoulder and a 6 ft wide left shoulder.

Figure 1. Aerial View of the Oregon Bridge Site (Image from Google)

Figure 2. Aerial View of the Wisconsin Bridge Site (Image from Google)

West Bound Bridge

Electrical Power Transformer

Latitude, Longitude 45.739506, -119.077732

West Bound Bridge

Electrical Utility Pole

Latitude, Longitude 44.883829, -89.423431

Figure 3. Underside View of the Wisconsin Bridge (Image from Google)

TRAFFIC WEIGHT AND CLASSIFICATION DATA COLLECTION

A new two lane pavement WIM system will be installed in the concrete roadway pavement approaching each of the two proposed bridges. The WIM systems will be of a double threshold design system in which two lines of weighing sensors are installed in each lane along with inductive loops. An overhead IP camera will also be installed at each WIM system to capture images of the trucks (according to vehicle classification criteria) and to associate them with the truck weight and classification measurements. The methods and procedures for the installation, calibration and validation of the WIM systems will conform to those outlined in ASTM E1318-09 (Standard Specification for Highway Weigh-in-Motion (WIM) Systems with User Requirements and Test Methods) for a Type 2 WIM systems and in the LTPP Field Operations Guide for SPS WIM Sites, Version 1.0 (July 6, 2012). LTBP draft protocols will be prepared for installation and validation of WIM sites at bridges based on these documents.

A general schematic of this WIM configuration is shown in Figure 4. Some of the vendors employ a set of two inductive loops, one leading and one trailing the weigh scales, to control the weight measurement sequence while others use only a single leading loop for this purpose. The schematic shown in the figure is for a system with a single inductive loop detector leading the weight sensors.

The new WIM system installed at each bridge site will provide the following information for each vehicle record: (1) record number, (2) date and time (3) lane number, (4) vehicle classification (FHWA), (5) vehicle speed, (6) GVW, (7) Axle Weights and (8) Axle Spacing. The overhead camera at the WIM system will record a snapshot image of each vehicle triggering the inductive loops, but only the images associated with designated vehicle classifications (trucks) will be associated with the vehicle weight record and retained.

Figure 4. Two Lane, Double Threshold WIM System with Leading Loop Detectors and Quartz Piezoelectric Weight Sensor

BRIDGE RESPONSE DATA COLLECTION

The bridges described previously will both be instrumented and monitored along with the truck weight and classification information from the new WIM sites to evaluate the effects of truck volumes and weights on their structural responses and long-term performance. The structural monitoring program devised for the bridges incorporates both short-duration, high-speed triggered measurements and slow-speed continuous measurements of representative structural responses.

The high-speed triggered monitoring scheme avoids the significant hardware, logistical and data analysis demands that would be imposed by high-speed measurements of the structural responses either on a continuous basis, or by recording the structural responses from the much larger numbers of light passenger vehicles crossing the bridges. This monitoring scheme also permits the response data due to truck crossings to be recorded with the high spatial and temporal resolutions necessary for reliable and scientific evaluation of the structural performance and behavior. The structural responses to be measured under this scheme will include strains on the deck underside and on the beams and accelerations. The bridge monitoring system will be triggered to record these responses when the strain measured at one or two designated locations on the bridge exceeds a predetermined threshold value.

The threshold strain values will be established from analysis of structural response measurements obtained from a controlled truck load test that will be performed on each bridge after the sensors have been installed, but prior to initiation of the long-term monitoring program.

An outdoor rated, Internet Protocol (IP) camera with an infrared illuminator will be installed at each bridge site in order to capture the traffic present on the instrumented span in its field of view. The cameras will be programmed to record a minimum of two photographs of the traffic on the bridge deck whenever a high-speed measurement sequence is triggered by a truck crossing. The recorded

Lineas Sensor 6

Lineas Sensor 5

Lineas Sensor 2

Lineas Sensor 1

Lineas Sensor 8

Lineas Sensor 7

Lineas Sensor 4

Lineas Sensor 3

To Instrumented Bridge

Loop

Loop

Lane 1

Lane 2

Minimum 150 ft of sufficiently flat pavement to start of bridge approach slab

Pavement Shoulder

Pavement Shoulder

Overview camera on pole and WIM electronics cabinet photographs will be associated with the triggered structural response measurements and used in conjunction with the measurement data analysis and for cross validation with truck weight, classification and vehicle image data collected from the new WIM stations.

The slow-speed continuous measurement scheme will measure and evaluate the structural responses of each bridge due to ambient environmental loads, such as thermal inputs, in parallel with the measured truck load induced responses. The structural responses due to environmental inputs are significant and the live load related responses are superimposed on the environmental related responses. The structural responses due to environmental inputs must be quantified and evaluated along with the responses due to trucks in order to reliably evaluate and assess the true impact of truck loads on long-term bridge behavior and performance.

Since the environmental inputs and the structural responses due to these stimuli are both slowly-varying, they can be continuously measured with a slow sampling rate without any risk of aliasing the measurement data. This approach generates a relatively small amount of data on daily basis, but maintains enough temporal resolution for reliable data interpretation. The slow speed measurements will be recorded in this monitoring program on a continuous basis (24/7) at a rate of 5 samples per sensor once per every 30 minutes. The slow-speed measurement sequence (one sample per sensor recorded from a total of five sequential sweeps through all of the sensors) will require a total time of approximately two minutes to complete. Temperature changes will be insignificant for the brief time duration over which the sequence of five measurements is completed. The discrete samples from each sensor will be graphically evaluated during the data analysis stage to identify measurement that is substantially inconsistent with the other samples from the same sequence. The consistent samples from each sensor will be averaged together in the data processing stage to provide a single measurement value for the 30 minute interval. This averaging process will minimize the effects of any live loads (cars or trucks) that may be present on the bridge when a given measurement is recorded.

A compact, all-in-one weather station will be installed at each bridge site that will measure a full spectrum of metrological characteristics including air temperature, air pressure, wind speed and direction, relative humidity, precipitation and solar radiation. The slow-speed continuous measurements of the bridge structural responses (strains, displacements, tilts and structural temperatures) will be correlated and evaluated with the specific metrological parameters influencing those structural responses. The specific metrological parameters expected to be evaluated in conjunction with the bridge response measurements include air temperature, solar radiation, and relative humidity. The bridges monitored for this research will become reference bridges for the LTBP Program and historical climatic data for the sites will be collected according to LTBP Protocol PRE-ED-BD-004 Site Conditions.

Sensor Types

The majority of the sensors to be installed on the bridges will be vibrating wire type sensors. Vibrating wire sensors are designed to measure a specific physical parameter such as strain, tilt, or displacement along with the temperature at the sensor location. Until recently, vibrating wire sensors were only suitable for slow-speeds or quasi-static measurements. Dynamic vibrating wire measurement hardware recently developed enables these sensors to be measured at much higher rates (20 Hz, 50 Hz, 100 Hz or 200 Hz sampling rates). This dynamic measurement hardware also permits the same sensors to be simultaneously measured at a quasi-static rate to record the structural responses due to environmental inputs. This capability represents a significant advantage in that it overcomes the need to employ separate sensors to measure the structural responses due to live loads and due to environmental inputs.

This significantly reduces the overall cost and complexity of the monitoring system.

Dynamic vibrating wire measurement hardware will be used at each bridge with vibrating wire strain gages to measure the structural responses of the deck and beams due to truck loads and environmental inputs. In the high-speed triggered measurement scheme, the strain gage measurements will be recorded at a rate of 200 Hz (samples per second) for a total duration of 4 seconds during each truck crossing event. The corresponding number of measurement samples that will be recorded from each strain gage on the bridge per foot of truck movement across the instrumented spans is shown for various vehicle speeds in Table 1. The same hardware and strain gages will also record the structural responses due to environmental inputs at a rate of 5 samples per sensor every 30 minutes.

Strain Gages

Two different variations of the same vibrating wire strain gage will be used for the bridges. Strain gages will be installed on concrete elements such as the deck underside or prestressed concrete beams. Strain gages will be installed on steel elements such as welded plate girders and crossframes. The strain gages also feature a thermistor for recording the sensor (and structure) temperature at the installation location. These vibrating wire gages feature a ruggedized design that has proven successful for long-term measurement applications in harsh environments, but a separate protective cover will be installed over each gage to further improve their long-term hardiness and to minimize any potential for temperature differences between the sensor and the structural element at the gage attachment locations.

Tiltmeters and Displacement Sensors

Vibrating wire type sensors will also be used for all displacement and tilt measurements on each bridge structure. These sensors will only be measured under the slow-speed continuous measurement scheme to track the structural responses due to environmental inputs to the bridges. Vibrating Wire Tiltmeters will be used to measure the slowly-varying rotations of the beam ends and substructure elements. Each tiltmeter also includes a thermistor for measuring the temperature of the sensor at its installation location. A dampening fluid can be injected into the tiltmeter to counteract the effects of structural vibrations on the long-term measurements.

The vibrating wire sensors that will be used for displacement measurements These sensors will be used to measure the longitudinal displacements of the prestressed beams and steel plate girders at the expansion bearing locations. The sensors are equipped with universal joints at each end permitting a wide array of attachment methods. Each displacement sensor also includes a thermistor for measuring the temperature of the sensor at its installation location.

Accelerometers

Accelerometers will be installed on both bridges to measure and track the dynamic impact effects of various truck loads and their interactions with the approach slab and roadway pavement leading up to the bridge. The accelerometers will also measure the live load induced free vibration response of the instrumented spans as a truck exits the bridge. The accelerometers measurements will only be recorded during triggered high-speed measurements when a truck crosses the bridge. Accelerometers will be used on the stiffer prestressed concrete beam bridge to minimize the potential for the vibrations to exceed the input range of the sensors.

Weather Station

A weather station will be installed at each bridge to measure the complete spectrum of environmental conditions at the site. The weather station will be an all-in-one type sensor with a digital communication interface that can measure the following metrological parameters: (1) Air Temperature, (2) Relative

Humidity, (3) Precipitation Intensity, (4) Precipitation Type (rain/snow), (5) Precipitation Quantity, (6) Air Pressure (barometric pressure), (7) Wind Speed, (8) Wind Direction, and (9) Solar Radiation.

The weather station includes a heater to prevent the sensors from freezing during snow/ice conditions.

However, all of the metrological measurements produced by the weather station will be archived and evaluated in conjunction with the data collection program for LTBP Program reference bridges.

IP Camera

Camera will be installed at each bridge site to capture images of the traffic on the instrumented bridge span when the high-speed triggered measurement sequence is activated by a truck crossing the structure. It is a high definition network camera It has built-in white light and infrared illuminators and is a true day/night camera.

Instrumentation Plans for the Proposed Bridge Sites

The following sections illustrate the layout of the sensors described above for each of the bridge sites.

The sensors will generally be located at a number of transverse lines (instrumented sections) along the bridge span. These instrumented sections are typically located at the bearing locations, the midspan location of the bridge, the location of a diaphragm beam or intermediate crossframe, and one additional section in the span. The instrumented sections at the bearings include tiltmeters and displacement transducers for measuring the deformations of the beams and substructures.

The remaining instrumented sections include strain gages installed on the vertical cross section of the beams, the underside of the concrete deck, and on select diaphragm beams and intermediate crossframes. The strain gages will be used to evaluate the behavior of these elements due to truck loads and environmental inputs. The strain gages installed on the vertical cross section of the beams will be used to evaluate the bending behavior of each beam, the location of the neutral axis for the composite deck, and the distribution of bending moments across the width of the structure. The strain gages installed on the underside of the concrete deck will measure longitudinal and transverse strains. These gages will be installed at three locations between the beams to measure the distribution of deck strain between the beams due to composite section behavior, and due to global transverse and longitudinal bending of the deck. The strain gages installed on the diaphragm beams and intermediate crossframes will be used to evaluate the behavior of these elements in distributing the truck live loads between the beams.

A limited number of accelerometers will be placed at several locations on each bridge to measure the global and local dynamic response of the bridge due to different truck weights and configurations, and for tracking how the approach slab and deck joint conditions influence the dynamic response of the bridge. The specific locations of the instrumented sections and the arrangements of the sensors on the structural components of each bridge are described in the following.

Oregon Bridge

A general schematic of the framing plan for the center span (Span 2) of the Oregon Bridge is shown in Figure 5. The spatial relationship between the traffic lanes and shoulders to the prestressed beams is shown in Figure 6. This illustrates that Beam 2 thru Beam 5 will be subject to the majority of live load and Beam 3 is the most likely to be frequently loaded by trucks. The bridge will be instrumented using a total of 93 strain gages, 10 tiltmeters, 4 displacement gages, and 7 accelerometers.

The locations for the instrumented sections for Span 2 of the bridge are illustrated in Figure 7.

Instrumentation Section A and Section E are located at Bent 3 and Bent 2, respectively. Section B is positioned at one of the two concrete diaphragm beam locations and is at the approximate 1/3 point of the span length. Section C is positioned midway between the diaphragm beam line and the middle of the span. Section D is located at the middle of the span. The locations of the accelerometers are also shown in this figure. These sensors will primarily be installed on Beam 3 at the locations of the two diaphragm beams, midway between Bent 3 and the first diaphragm beam location, and at the middle of the span. Accelerometers will also be installed on Beam 1 and Beam 6 at the middle of the span to capture the spatial character of the dynamic effects due to truck crossings. There will be one instrumentation section located in the middle of Span 3 (the eastern end span). The concrete deck is continuous for live loads, so the sensors in this location can be used for evaluating and tracking this characteristic for truck loads. The sensors located in the end span will also serve as the trigger sensors for the high-speed measurement scheme for Span 2.

Figure 5. General Schematic of the Framing Plan for the Center Span of the Oregon Bridge

78’-10” C to C Brgs.

26’-1” 26’-1”

Diaphragm Beams

Diaphragm Beams26’-8”

Bent 2 (Pin)

Bent 3 (Free)

Figure 6. General Schematic of Superstructure Cross Section and Roadway Configuration on Bridge

Figure 7. Instrumented Section Locations in Span 2 of the Westbound Traffic Bridge

Superstructure Cross Section Looking West

1236 45

Rt. Shoulder 10’-0”

Lt. Shoulder 6’-0”

Lt. Lane 12’-0”

Rt. Lane 12’-0”

5 Equal Beam Spaces @ 7’- 4 ¾”± = 37’-0”

78’-10” C to C of Brgs.

D BC

Bent 2 (Pin)

Bent 3 (Free)

AE

Instrumentation Sections – Span 2 Plan View

Vertical Accelerometers to be installed on prestressed beams (Qty = 6)

Instrumentation Sections A and E

The arrangement of tiltmeters and displacement gages on the structure at Sections A and E are illustrated in Figure 8 and Figure 9, respectively. Instrumentation Section A, which is located at the free end of Span 2, will have three tiltmeters installed on the concrete diaphragm beams located between Beams 1 and 2, Beams 3 and 4, and Beams 5 and 6. The tiltmeters will measure the longitudinal end rotation of the superstructure relative to the substructure across its transverse width due to thermal inputs and other long-term effects. Two additional tiltmeters will be installed on the top of the concrete cap beam at Bent 3 to measure its longitudinal rotation globally and with respect to the superstructure due to thermal loads and other long-term effects. A total of four linear displacement sensors will be used to measure the longitudinal displacements due to thermal loads of the two exterior beams and two of the interior beams of the skewed superstructure. Instrumentation Section E (Figure 9) is located at the pinned end of the span and includes a total of five tiltmeters arranged in the same manner on the structure as for Section A.

Instrumentation Section B

Instrumentation Section B includes a total of 18 strain gages installed on all of the prestressed concrete beams as shown in Figure 10. Since this instrumented section is at one of the concrete diaphragm locations, the strain gages will be installed on the prestressed beams a minimum distance of 6 in away from the face of the diaphragm beam towards the middle of the span. A total of three strain gages will be installed at different points along the 45 in height dimension of each beam. One strain gage will be placed on the bottom flange of each beam, another will be installed on the web a distance of 16 in above the bottom flange, and the final strain gage will be placed near the top flange. This arrangement will permit the neutral axis location for the composite deck and beams to be determined and the distribution of moment between all of the beams to be measured under truck loads. The strain gages located near the bottom of the beam cross section will both be located away from the neutral axis should provide large enough strain measurements to reliably quantify the neutral axis location. The strain gage located near the top flange will be located near the neutral axis of the composite section and may measure small strains under truck loads, but these measurements will serve to validate the position of the neutral axis determined from the other two strain gages on the beam. They will also be used to evaluate the beam strains near the interface of the deck and beams and for characterizing the beam response due to thermal inputs.

Figure 11 shows the arrangement of the 18 strain gages that will be installed on the underside of the deck at Instrumentation Section B. These gages will be installed on the deck underside between Beams 2 and 3, Beams 3 and 4, and Beams 4 and 5 since only this region of the deck will be directly loaded by truck wheel loads. A total of 3 longitudinally oriented strain gages and 3 transversely oriented strain gages will be installed on the deck between each of the beams. The strain gages measure the bending and membrane strains on the deck underside due to local (wheel) and global (overall truck) live load effects. The longitudinal strain gages will also be used to characterize the effective flange width of the composite deck-beam section due to truck loads. They will also be used to validate the lane occupancy and to validate multiple presence characteristics for each truck crossing event. Finally, the longitudinal strain gages can be used to validate axle count and spacing information obtained from the WIM system measurements. The strain gages installed on the deck underside will also be monitored under the slow-speed continuous measurement scheme to track the behavior of the composite deck-beam sections and of each to the components to thermal loads and other long-term effects. The strain gages will be installed on the deck underside a minimum distance of 6 in from the face of the concrete diaphragm beam towards the middle of the span at Instrumentation Section B.

As shown in Figure 12, a total of 12 strain gages will be installed on the concrete diaphragm beams located at Section B. These strain gages will only be installed on the diaphragm beams between Beams 2 and 3, Beams 3 and 4, and Beams 4 and 5. Two transverse strain gages will be installed near the top and bottom of each diaphragm beam section near its ends. The strain gages will measure the bending and axial strain on the diaphragm due to local and global truck load effects. These gages will also be measured under the slow-speed continuous measurement scheme to track their behavior due to thermal loads and other long-term effects.

Figure 8. Tiltmeters and Displacement Sensors at Instrumentation Section A

Figure 9. Tiltmeters at Instrumentation Section E

1 2 3 64 5

VW Tiltmeter - Longitudinal Direction on Bent (Qty = 2)

VW Linear Displacement – Beam relative to Bent (Qty = 4)

VW Tiltmeter - Longitudinal Direction on Diaphragm Beam (Qty =3)

Instrumentation Section A Looking East at Bent 3 (Free)

6 5 4 13 2

VW Tiltmeter - Longitudinal Direction on Bent (Qty = 2)

VW Tiltmeter - Longitudinal Direction on Diaphragm Beam (Qty =3)

Instrumentation Section E Looking West at Bent 2 (Pin)

Figure 10. Strain Gages on Prestressed Beams at Instrumentation Section B

Figure 11. Strain Gages on Deck Underside at Instrumentation Section B

Figure 12. Strain Gages on Concrete Diaphragm Beams at Instrumentation Section B

Prestressed Concrete Beams - Instrumentation Section B Looking West

6 5 4 13 2

VW Longitudinal Beam Strain (Qty = 18)

Deck Underside – Instrumentation Section B Looking West

5 4 3 2

VW Transverse Deck Strain (Qty = 9)

VW Longitudinal Deck Strain (Qty = 9)

Diaphragm Beams – Instrumentation Section B Looking West

5 4 3 2

VW Transverse Strain on Intermediate Diaphragm Beams (Qty = 12)

Instrumentation Section C

Figure 13 shows the strain gage arrangement for the prestressed concrete beams at Section C. One strain gage will be installed on the bottom flange of the six prestressed concrete beams at this section.

This section is located away from the concrete diaphragm beam locations where the transverse bending stiffness of the superstructure will be minimized. These strain gages will provide a redundant measurement of the distribution of bending strains among all of the beams for truck loads. This will be used to validate the bending distribution factors that will also be measured at the middle of the span (Section D) where there is also no diaphragm beam. This section will also provide additional spatial resolution for evaluating the global behavior of the superstructure under truck loads and thermal loads.

Instrumentation Section D

Instrumentation Section D will be located at the middle of Span 2 where there is no concrete diaphragm beam. Figure 14 shows the arrangement of the 18 strain gages that will be installed on the prestressed concrete beams at this transverse line. A total of three strain gages will be installed along the 45 in height dimension of each beam in the same manner as employed for Section B. The underside of the deck will also be instrumented with a total of 18 strain gages (Figure 15) in the same arrangement as employed for Section B.

Span 3 Instrumentation

A limited number of sensors will be installed at the middle of eastern end span (Span 3). The end spans of the bridge structure have five lines of prestressed beams versus the six lines in the center span. The relationship between the traffic lanes and the prestressed beams in the end span is shown in Figure 16.

The sensors that will be installed on the end span will include three strain gages and one accelerometer as is also shown in Figure 16. The accelerometer will be installed on Beam 3 and will be used to compare the dynamic effects and interactions between the adjacent bridge spans due to different truck loads and truck configurations.

The strain gages will be installed on the bottom flanges of Beam 2, Beam 3 and Beam 4. The strain gages will be used as trigger sensors for initiating the high-speed measurement scheme for Span 2 when a truck crossing is detected. The measurements from these strain gages will also be used to trigger three snapshots of the traffic on the bridge from the overview camera during the high-speed measurement sequence. Finally, the strain gages will characterize and track the interactions through the concrete deck, which is continuous for live load, between the adjacent bridge spans due to different truck loads and configurations.

Figure 13. Strain Gages on Prestressed Concrete Beams at Instrumentation Section C

Instrumentation Section C Looking West

6 5 4 13 2

VW Longitudinal Beam Strain (Qty = 6)

Figure 14. Strain Gages on Prestressed Concrete Beams at Instrumentation Section D

Figure 15. Strain Gages on the Deck Underside at Instrumentation Section D

Figure 16. Sensor Arrangement at Middle of Span 3 (East End Span)

Prestressed Concrete Beams - Instrumentation Section D Looking West

6 5 4 13 2

VW Longitudinal Beam Strain (Qty = 18)

Deck Underside – Instrumentation Section D Looking West

5 4 3 2

VW Transverse Deck Strain (Qty = 9)

VW Longitudinal Deck Strain (Qty = 9)

VW Longitudinal Beam Strain (Qty = 3)

Vertical Accelerometer (Qty = 1)

Rt. Shoulder 10’-0”

Lt. Shoulder 6’-0”

Lt. Lane 12’-0”

Rt. Lane 12’-0”

5 4 13 2

End Span Instrumentation Section – Middle of Span 3

Wisconsin Bridge

This instrumentation plan developed for this bridge is very similar to the plan devised for the Oregon bridge structure. The same reasoning that was used in determining the locations of the instrumentation sections and the arrangement of the sensors on the structural elements for the Oregon bridge structure was also employed for this bridge. This superstructure type and configuration for the Wisconsin bridge structure is different from the Oregon bridge structure, and consists of single simple span and with five longitudinal girder lines and five transverse lines of intermediate crossframes. This leads to slight differences in the overall sensor quantities that will be used to monitor each bridge. A general schematic of the superstructure framing plan for the bridge is shown in Figure 17. The spatial relationship between the traffic lanes and shoulders to the steel plate girders is shown in Figure 18. This schematic indicates that Girders 2, 3 and 4 are located directly below the traffic lanes. The bridge will be instrumented using a total of 95 strain gages, 10 tiltmeters, 5 displacement gages, and 6 accelerometers.

The sensors will be installed on the bridge along a total five different transverse lines (instrumented sections) also shown in Figure 17. Instrumentation Sections A and E are located at the East Abutment and West Abutment, respectively. The superstructure has fixed bearings at the West Abutment and expansion bearings at the East abutment. Instrumentation Section B is located 130 in (10.83 ft) to the east of the middle of the bridge span. This transverse line is located midway between two adjacent intermediate crossframe locations. Instrumentation Section C is located at the middle of the bridge span where there is a line of intermediate crossframes. Instrumentation Section D is located at the 2/3 point of the span length measured from the East Abutment location which also corresponds to the location of a line of intermediate crossframes. The locations of the six accelerometers that will be installed on the bridge are also shown in the figure. The accelerometers are arranged on the span in the same pattern as used for the center span of the Oregon bridge structure.

The arrangement of the sensors on the structure at Sections A and E are shown in Figure 19 and Figure 20, respectively. A linear displacement sensor will be used to measure the relative longitudinal displacement of each girder relative to the substructure at Section A. Section A and Section E both include a total of five tiltmeters with three located on the end diaphragm for measuring the end rotations of the superstructure relative to the abutment, and two located at the top of each abutment to measure the rotations of these elements.

Instrumentation Section B includes a total of 15 strain gages that will be installed on the 5 plate girders and 24 strain gages (12 longitudinal and 12 transverse) that will be installed on the underside of the deck in the spaces between each girder line as shown in Figure 21 and Figure 22, respectively. This instrumentation section is located between the locations of intermediate crossframes where the superstructure is more flexible in the transverse direction.

Instrumentation Section C includes a total of 15 strain gages installed on the 5 plate girders, 12 strain gages located on the crossframe elements, and 24 strain gages located on the deck underside as illustrated in Figure 23, Figure 24 and Figure 25. A single strain gage will be installed on each of the three angle sections that make up the crossframe to measure the local and global behavior of the crossframes due to truck loads, and thermal loading and other long-term effects.

Instrumentation Section D includes a single strain gage installed on the bottom flange of each plate girder as illustrated in Figure 26. This instrumentation section is located along a line of crossframes and will be used to validate the measured behaviors from Section C and to provide additional spatial resolution to the measurements of the global behavior of the superstructure.

Figure 17. Instrumented Section Locations for Wisconsin Bridge

Figure 18. General Schematic of Superstructure Cross Section and Roadway Configuration on Bridge

130’-0” C to C Bearings

Instrumented Sections – Wisconsin Bridge

W. Abut.

(Fix)

E. Abut.

(Exp)

5 Intermediate Crossframes - 6 Spaces @ 21’-8”

C BD AE

Vertical accelerometers to be installed on plate girders (Qty = 6)

Superstructure Cross Section Looking West (Parapets Not Shown)

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Rt. Shoulder 10’-0”

Lt. Shoulder 6’-0”

Lt. Lane 12’-0”

Rt. Lane 12’-0”

4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

Figure 19. Sensor Arrangement at Instrumentation Section A

Figure 20. Sensor Arrangement at Instrumentation Section E

Instrumentation Section A – East Abutment (Exp.)

Looking East

4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

54321

MC18x42.7 (Typ.)

VW Tiltmeter - Longitudinal Direction on Abutment (Qty = 2)

VW Longitudinal Displacement – Girder relative to Abutment (Qty = 5)

VW Tiltmeter - Longitudinal Direction on Diaphragm Beams (Qty =3)

Instrumentation Section E – West Abutment (Fix) Looking West

4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

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MC18x42.7 (Typ.)

VW Tiltmeter - Longitudinal Direction on Abutment (Qty = 2)

VW Tiltmeter - Longitudinal Direction on Diaphragm Beams (Qty =3)

Figure 21. Sensor Arrangement on Steel Plate Girders at Instrumentation Section B

Figure 22. Sensor Arrangement on Concrete Deck Underside at Instrumentation Section B

Figure 23. Sensor Arrangement on Steel Plate Girders at Instrumentation Section C

Instrumentation Section B – Plate Girder Sensors Looking West

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4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

VW Longitudinal Girder Strain (Qty = 15)

Instrumentation Section B – Reinforced Concrete Deck Sensors Looking West

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4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

VW Transverse Deck Strain (Qty = 12)

VW Longitudinal Deck Strain (Qty = 12)

Instrumentation Section C – Plate Girder Sensors Looking West

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VW Longitudinal Girder Strain (Qty = 15)

Figure 24. Sensor Arrangement on Intermediate Crossframes at Instrumentation Section C

Figure 25. Sensor Arrangement on Concrete Deck Underside at Instrumentation Section C

Figure 26. Sensor Arrangement on Steel Plate Girders at Instrumentation Section D

Instrumentation Section C – Intermediate Crossframe Sensors

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4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

VW Strain on Intermediate Crossframe Angles (Qty = 12)

Instrumentation Section C – Reinforced Concrete Deck Sensors Looking West

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4 Spaces @ 9-0” = 36’-0” 3-6”3-6”

VW Transverse Deck Strain (Qty = 12)

VW Longitudinal Deck Strain (Qty = 12)

Instrumentation Section D – Plate Girder Sensors Looking West

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VW Longitudinal Girder Strain (Qty = 5)

Data Acquisition Systems

The data acquisition systems to be used for each bridge will employ the same basic configuration. A local area network (wired Ethernet) will be implemented on each bridge. The data acquisition devices components will be located in a number of weatherproof enclosures that will be located close to the sensors to minimize the cabling required from each sensor to an enclosure.

Figure 27. Data Acquisition Enclosure Locations for Oregon Bridge

Figure 28. Data Acquisition Enclosure Locations for Wisconsin Bridge

D BC AE

Bent 2 Bent 3

Data Acquisition Enclosure Locations – Oregon Bridge Span 2

Plan View

Data Acquisition Enclosure Locations – Wisconsin Bridge

Plan View

W. Abut.

(Fix)

E. Abut.

(Exp)

E

BCD

Data File Size Estimates

An analysis was performed in order to estimate daily and annual measurement data files sizes to determine the expected order of magnitude of the measurement data that will need to be transferred from the bridge sites over a cellular wireless connection and managed and archived on a local server.

The measurement data generated by the high-speed triggered monitoring scheme and by the slow-speed continuous monitoring scheme were both evaluated. The Oregon bridge site was used as the controlling case for the data file size assessment since this bridge has a higher ADTT value than the Wisconsin bridge. The higher ADTT value will lead to a larger number of short-duration, high-speed measurement sequences and larger data file sizes.

The number of daily trigger (truck crossing) events is assumed to be 2,500 which is conservative relative to the 2014 ADTT of approximately 2,150 reported for the Oregon bridge site. The triggered high-speed sampling rate will be 200 samples per second (200 Hz) and 100 high speed sensor inputs are assumed at this rate. The sampling duration for each high-speed triggered event will be 4 seconds, and the data size per sample (IEEE4 Format) of a single channel will be 4 bytes. The number of samples per sensor for the 4 second sampling duration is 800 leading to a data file size of 320,000 bytes (0.320 MB) for all sensors from each truck crossing event. Assuming 2,500 trigger events per day, the daily data file size will be

0.80 GB. The data file size per week will be 5.60 GB, and the annual data file size generated will be

291.20 GB.

The overhead camera will record two images of the bridge traffic during each truck crossing event.

Assuming a conservative file size of 250 KB (0.25 MB) for a 1280 x 720 JPEG image file, the size of the image files generated per truck crossing event will be 0.5 MB. The size of the image files generated for 2,500 trigger events per day will be 1.25 GB. The image file size generated per week would be 8.75 GB and the image file size generated per year will be 455 GB.

The measurement data file size that will be generated by the slow-speed continuous (24/7) monitoring scheme was also estimated. This measurement scheme includes all vibrating wire sensors and their thermistors, and the weather station sensors. The total channel count is 217 (107 vibrating wire sensors, 107 thermistors, and 3 weather station sensors) and the sampling interval is 30 minutes. The number of sample intervals per day will be 48 and 5 samples will be recorded for each channel during each sample interval. The file size for each channel will be 4 bytes (IEEE4 format) and the total data file size per sampling interval will be 4,340 bytes. The data file size generated each day will be 0.208 MB, the data file size generated per week will be 1.46 MB, and the data file size generated per year will be 75.8 MB.

The daily, weekly and annual data file sizes for the WIM system measurements were also estimated using data size information obtained. WIM vehicle records generally range from 500 bytes for a two axle vehicle to 1500 bytes for a five axle vehicle. Using the 2014 ADTT numbers from the Oregon bridge site as the controlling case, the daily two-axle and five-axle vehicle counts are conservatively estimated at 5,000 and 2,500, respectively. These counts would result in a daily WIM data file size of 6.25 MB (2.5 MB for two axle vehicles and 3.75 MB for five axle vehicles). The size of the weekly WIM data file would be

43.75 MB and the size of the annual WIM data file would be 2.3 GB. The overhead IP camera at the WIM system would be expected to generate image file sizes of 625 MB, 4.4 GB and 228 GB on a daily, weekly and annual basis assuming image files are only retained for trucks. The image file size estimate assumes the same parameters for each image file’s size as used for the overhead camera at the bridge.

In summary, a conservative estimate of the data file sizes that will be generated on an annual basis for each bridge will be 291 GB for the high-speed triggered measurement data, 455 GB for bridge traffic images, and 76 MB for slow-speed continuous measurement data. Therefore, the bridge monitoring data that will need to be transferred over the cellular wireless network connection will be approximately

2 GB per day. A corresponding conservative estimate for the annual WIM system vehicle data record file size is 2.3 GB and 228 GB for truck images from an overhead camera at the WIM site. A separate cellular modem dedicated to the WIM system will need to transfer approximately 630 MB to an off-site server for analysis on a daily basis. The overall size of the measurement data files that might be generated on an annual basis from each bridge sites is just under 1 TB per year. The off-site server will easily accommodate a data archive of such size. Furthermore, a significant portion of this data (on the order of 70%) will be image files of the traffic on the bridge during high-speed triggered measurement scans and of the trucks crossing the WIM scales.

COMMISSIONING AND CALIBRATION OF WIM AND BRIDGE MONITORING SYSTEMS

The WIM systems will be calibrated and the bridge monitoring systems for the Oregon and Wisconsin bridges will be validated before the initiation of the long-term monitoring program. The initial calibration of the WIM systems will be performed by the selected WIM system vendor according to the ASTM E1318-09 Standard (Standard Specification for Highway Weigh-in-Motion (WIM) Systems with User Requirements and Test Methods) after the systems have been installed. The WIM systems will be subject to validation programs during their operation to ensure the WIM systems produce research quality truck weight and classification data over the duration of this research program using the procedures implemented for pavement WIM systems under the Long Term Pavement Performance Program (LTPP) and as outlined in “LTPP Field Operations Guide for SPS WIM Sites, Version 1.0” and dated July 6, 2012.

The performance of the bridge monitoring systems will be validated after installation by conducting a controlled truck load test of each bridge. This first load test will be used to obtain an initial validation of the monitoring system components (sensors, data acquisition hardware, cabling, and network and communications devices) as an integrated system and to define the threshold strain values to be used in conjunction with the high-speed triggered monitoring scheme. The sensors to be monitored for the trigger strain thresholds will be those located on the bottom flange of beams located directly under the traffic lanes. The threshold values will be set to a minimum value such that all trucks (loaded or unloaded) crossing the bridges will trigger the high-speed measurement sequence.