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New Products for Static Load Testing – Vibrating-Wire Strain
Gages, and the Static Load Tester (SLT) System
Van E. Komurka, P.E., D.GE
Pile Dynamics, Inc. Representative Days
September 27 – 29, 2017
New Products for Static Load TestingTopics Outline
• New PDI Product – Vibrating-Wire Strain Gages• Surface-Mounted
• Strainmeters
• What is a Static Load Test?
• Static Load Test Instrumentation
• New PDI Product – Static Load Tester (SLT) Datalogger System• SLT Data Acquisition Box (DAB)
• SLT Computer
Surface-Mounted Vibrating-Wire Strain Gages
• Mounts to the surface of a driven or bored pile
• Mounts above-grade on concrete and steel piles to provide additional information on applied load and/or the test pile’s elastic modulus
• Can be mounted below-grade on steel piles to determine load in a static load test pile at different elevations – determine shaft resistance distribution – correlate to dynamic testing results – refine design (potentially shorten piles)
• Gages will come with a smart connector
Vibrating-Wire Strainmeters (“Sister Bars”)
• Are cast into the concrete of a prestressed concrete pile, a concrete-filled pipe pile, or a bored pile
• Are generally tied to other reinforcing
• Can be installed below-grade within concrete to determine load in a static load test pile at different elevations – determine shaft resistance distribution –correlate to dynamic testing results – refine design (potentially shorten piles)
• Gages will come with a smart connector
New Products for Static Load TestingTopics Outline
• New PDI Product – Vibrating-Wire Strain Gages• Surface-Mount
• Strainmeters
• What is a Static Load Test?
• Static Load Test Instrumentation
• New PDI Product – Static Load Tester (SLT) Datalogger System• SLT Data Acquisition Box (DAB)
• SLT Computer
• Load is applied at the pile head
• Potential instrumentation:• Above-Grade:
• Jack Pressure
• Applied Load
• Head Movement (test pile, and reaction piles)
• Pile Strain (test pile, and reaction piles)
• Tilt
Top-Loading Static Load Test
Top-Loading Above-Grade Instrumentation
Top-Loading Static Load Test
• Load is applied at the pile head
• Potential instrumentation:• Below-Grade:
• Pile Strain
• Telltales
• Tilt
Top-Loading Below-Grade
Instrumentation
Top-Loading Below-Grade
Instrumentation
For prestressed concrete piles, sister bar
strainmeters are installed in the casting yard
Bi-Directional Static Load Test
• Load is applied somewhere along the pile length (below-grade)
• Instrumentation potentially read:• Above-Grade:
• Head Movement
Bi-Directional Static Load Test
• Load is applied somewhere along the pile length (below-grade)
• Instrumentation potentially read:• Below-Grade:
• Jack Pressure
• Jack Expansion
• Pile Strain
• Telltales
Bi-Directional Below-Grade Instrumentation
Need for a Datalogger
• Static load tests may require many types of instrumentation to be read by a datalogger
• Static load tests may require many numbers of instrumentation to be read by a datalogger
• In photo at right:
• Test pile had 74 below-grade strain gages alone
• Took an entire day to wire the datalogger in the field
New Products for Static Load TestingTopics Outline
• New PDI Product – Vibrating-Wire Strain Gages• Surface-Mount
• Strainmeters
• What is a Static Load Test?
• Static Load Test Instrumentation
• New PDI Product – Static Load Tester (SLT) Datalogger System• SLT Data Acquisition Box (DAB)
• SLT Computer
Static Load Tester (SLT) Data Acquisition Box
(DAB)• Compact, lightweight, water-
resistant
• Reads virtually all types of static load test instrumentation
• 30 hours of battery life
• Storage capacity for 4,000 readings (more coming soon)
• 16 input channels per box: 12 analog, and 4 digital
Static Load Tester (SLT) Data Acquisition Box
(DAB)• Additional boxes can be
connected together to provide as many channels as required (coming soon)
• All channels can be configured by user, or automatically when using PDI sensors with a smart chip
• PDI will install smart-chip connectors on customers’ existing instrumentation at no charge
New Products for Static Load TestingTopics Outline
• New PDI Product – Vibrating-Wire Strain Gages• Surface-Mount
• Sister Bars
• What is a Static Load Test?
• Static Load Test Instrumentation
• New PDI Product – Static Load Tester (SLT) Datalogger System• SLT Data Acquisition Box (DAB)
• SLT Computer
Static Load Tester (SLT) Computer
• Currently consists of a dedicated SLT computer
• With an SLT module installed, a PDA-8G unit can be used (coming soon)
• Interfaces with SLT Data Acquisition Box via proprietary serial data cable, or Bluetooth®, (WiFi coming soon)
• Saves all readings it receives
• SiteLink® capable
Static Load Tester (SLT) Computer
• Programmable save intervals
• User-configurable real-time plots of:
• Load vs. Displacement
• Load vs. Time
• Strain vs. Displacement (coming soon)
• Strain vs. Time (coming soon)
• Generates user-configurable data tables, and plots, in PDF and JPG format for download to user’s PC
Questions / Comments?
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