Details:

Creators:
Siwula, John ; Helwany, Sam
Siwula, John ; Helwany, Sam Less -
Corporate Creators:
Wisconsin Highway Research Program ; Wisconsin. Department of Transportation
Wisconsin Highway Research Program ; Wisconsin. Department of Transportation Less -
Corporate Contributors:
HNTB Corporation ; University of Wisconsin--Milwaukee
HNTB Corporation ; University of Wisconsin--Milwaukee Less -
Subject/TRT Terms:
[+]
Concrete Construction Concrete Curing Concrete Placing Pile-driving Vibration Pile Driving Vibration
Publication/ Report Number:
No. 0092-06-04
Resource Type:
Brief
Geographical Coverage:
Wisconsin
Corporate Publisher:
Wisconsin Highway Research Program
Abstract:
For many years, engineers have measured and regulated the impacts of pile driving on existing structures. Vibrations from pile driving can impact buildings, affect safety and also be a major annoyance to people and businesses. However, while pile driving typically occurs early on highway projects, on complex projects the pile driving may occur concurrently with other work. In these cases, the vibrations from pile driving might not just impact surrounding properties – they may also affect recently placed concrete on the highway project itself. What’s the Problem? To allow for concrete to properly cure, WisDOT’s Standard Specifications regulate the distance of pile driving from early-age concrete and limit how soon pile driving can occur after the concrete has been placed. While the the impacts of pile-driving vibration on existing structures has been well established, fewer studies have evaluated the impacts on fresh concrete and results published to date for research in this area vary. With the scarcity of conclusive research recommendations, state specifications tend to take a conservative approach. WisDOT currently requires pile driving to be kept at a distance of 15 feet or more from a concrete-filled pile shell until it has cured for at least seven days. This specification does not mention freshly placed concrete structures such as footings. Research Objectives: This research evaluated the potential of pile-driving vibrations to damage concrete-filled pipe piles and recently placed structures in which concrete is still curing. The study measured how the vibrations diminished with distance and depth from their source, and established a relationship to concrete performance through evaluation of the effects of distance and elapsed curing time on the compressive strength of recently placed concrete. Methodology: After carrying out a literature review of related research, the investigators took the following steps to study the impacts of construction vibration on early-age concrete: Finite element modeling to evaluate the effects of varying pile sizes, pile types and hammers. A laboratory study of the compressive strength of concrete samples exposed to varying levels of vibration at different times during curing. A field evaluation of the compressive strength of concrete block samples placed at varying times and subjected to pile driving vibrations. Results: These analyses yielded the following results: Finite element modeling (FEM). Compared to empirically based equations and predictive models based on field tests, finite element modeling proved effective. FEM accommodates a number of variables not included in these other approaches, and simulates complicated soil-pilehammer interactions well in two-layer and single-layer soil systems. Laboratory. Researchers subjected 90 12-inch concrete cylinders and 36 concrete beams to 15 minutes of vibration each. Both the level of vibration and concrete curing time were varied Generally, vibration levels and elapsed curing time had little impact on the stiffness and strength of specimens tested at three, seven and 28 days. However, beams that were vibrated very early– within four to six hours of pouring–had substantially less strength than the three-day average of control beams. Field. Investigators placed 72 cast-in-place pullout cylinders and 24 pullout beams at varying distances from the vibration source (pile driving) in the field, then drove two test piles at different times within their curing periods. Placing materials at different distances allowed for the concrete to experience varying vibration levels. Geophones on the surface and at depths of 10 feet measured vibrations in relation to distance. The field data showed more variability than the laboratory data, but vibration level and curing time again seemed to have little impact on the compressive strength of specimens tested at three, seven and 28 days. As a result of this study, investigators recommended that WisDOT consider modifying the Standard Specifications to reduce the required distance of pile driving from early-age concrete in pile shells to 10 feet rather than 15 feet and to shorten the required curing time to five days rather than seven days. Study results indicate that these adjustments will still allow concrete to meet its design strength, but will also allow more rapid construction, which will save money and reduce inconvenience to the public.
Content Notes:
This brief summarizes Project 0092-06-04, “Construction Vibration Attenuation with Distance and Its Effect on the Quality of Early-Age Concrete.”
Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:faa171f0a4ced120ac168cade8767179367ad54c38c98e978d48680c210d278d
Download URL:
https://rosap.ntl.bts.gov/view/dot/61070/dot_61070_DS1.pdf
File Type:

Supporting Files

• No Additional Files

More +