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  • Relative Elevation Data Analysis on Newly Constructed Residential Foundations

    Author: Arthur S. Koenig, P.E., 1991
    Sponsor: Expansive Clay Research Institute - ECRI Publication #001

    ABSTRACT
    Many forensic engineers perform foundation distress studies on residential structures. One of the first tasks of such investigations is to make judgements concerning how much movement the foundation has experienced. It is commonly accepted that residential foundations can be placed out of level, and that in some cases, this may account for some, if not all, of the elevation differences measured during the examinations. For example, engineer's have been overheard saying something along the lines of, "I looked at a foundation that was 2 inches out of level, but it was probably constructed that way."

    This paper explores and answers the question raised by such remarks; namely the question of how much "out of level" are newly constructed foundations. The paper presents the statistical results of a study to measure the relative elevations of points at the middle and perimeter of residential foundations within several weeks of initial placement.

    The study indicates that residential foundations are actually placed within a much narrower band of error than commonly thought. The paper provides data allowing performance judgements to be supported by facts rather than speculation.

    Keywords: foundations, structural engineering, geotechnical engineering, forensic, elevations, relative elevations, floor flatness, foundation distress, statistics, water level, engineering, homebuilder, residence

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  • Slab-on-Grade Deflection: How Much Is Too Much?

    Author: Arthur S. Koenig, P.E., 1991
    Sponsor: Expansive Clay Research Institute - ECRI Publication #002

    ABSTRACT
    This paper presents an analysis of floor slab deflection data on 148 distressed residential dwelling foundations prior to their repair by underpinning. The intent of the study was to determine just how "bad" foundation distress had to get before homeowners' felt that problems needed correction, i.e., that there was a structural "failure" needing correction. The indicator of distress studied was that of maximum deflection from high to low point on the distressed slab.

    Keywords: foundations, structural engineering, geotechnical engineering, forensic, elevations, relative elevations, floor flatness, foundation distress, statistics, water level, engineering, homebuilder, residence, underpinning, economics

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  • Soil Moisture Levels Under Slabs Having Plumbing Leaks 1991

    ABSTRACT
    Foundations constructed over expansive clays can experience substantial heaving movement related to moisture content changes in the soils brought about by leaking water or sewer lines.

    Due to the introduction of new technology that is able to conveniently obtain high quality continuous Shelby tube samples from underneath foundations, information is being collected that forms a data base for evaluation of the moisture and physical property characteristics of such wetted soils.

    This paper presents the general difference characteristics that have manifested themselves upon analysis of soils from underneath foundations that have water leaks, or "free water" zones and those that don't. The data gathered thus far indicates that there is a definite and measurable moisture wave front associated with "leak wetted" soils. It also indicates that a key indicator of free-water wetted soil is the value of soil-moisture and its relation to the soil plastic limit. Soils under slabs with leaks, or observed ground water intrusion, have moisture contents that are at or above the Plastic Limit. The water leak cases studied presented moistures approximately 2 to 3 points above the PL. Ground water intrusion cases had moistures in the ground water zone of 5 to 8 points above the PL. Areas of soils affected by tree roots, as known from roots in the samples, had moistures that were approximately 2-3 points below the PL in the high moisture zones and 5-9 points below the PL in the low moisture zones. Investigation of structures not having water leaks or free-water indicates that the moisture content under the central portions of a foundation should normally be expected to have a high of "at or slightly below" the PL.

    Comparison of the two soils moisture scenarios of leakage vs. no leakage indicates that the Moisture Index, defined as the ratio of MC/PL, is a good criteria for evaluation of abnormal wetness. Water leak or otherwise free water wetted soils appear to have MI's of above 1. Normal soils appear to have MI's generally less than 1.

    Keywords: foundations, structural engineering, geotechnical engineering, forensic, elevations, relative elevations, floor flatness, foundation distress, statistics, water level, engineering, homebuilder, residence, moisture index, plumbing leakage, soil samples, shelby tube, GeoSampler

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  • MDI LABS Soil Sampling System ~ Description and Forensic Applications

    Author: Arthur S. Koenig, P.E., 1991

    ABSTRACT
    Sampling equipment has recently been developed that makes possible the gathering of good quality, continuous Shelby tube samples and performing of penetration testing from within confined or environmentally sensitive spaces such as commonly occur in buildings.

    The procedure is relatively easy and results in a much more meaningful and useful data than that derived from borings from outside, or that derived from talking auger or impact samples from within. This paper discusses the general features of the newly developed equipment and presents some typical scenarios, derived from actual case studies, outlining its use and benefits.

    Keywords: foundations, structural engineering, geotechnical engineering, forensic, elevations, relative elevations, floor flatness, foundation distress, statistics, water level, engineering, homebuilder, residence, GeoSampler, soil sampling, soil samples, shelby tube, MDI Labs, xGEL Data Systems, LLC, ECRI

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  • Economic Impact of the Texas Insurance Claims Market to Texas

    Author: Arthur S Koenig, PE
    Sponsor: Expansive Clay Research Institute (ECRI)

    ABSTRACT
    This paper discusses the "above the horizon" and the "behind the scenes", structure and operation of the Texas Insurance Claims Market in the years 1994-2003, and gives yearly hole counts, $ revenue, and $ expense numbers for one of the leading providers of drilling and testing and reporting for this foundation claims market.

    The paper also discusses the overall financial impact and discloses the yearly $ revenues that were paid to the various contract laboratories in the San Antonio, Houston, and Dallas market, and shows the substantial financial impacts of this work. It proposes a revision to the existing models of engineering business operations and concludes that ecosystem partnering is a tool that yields great benefit to all parties.

    Keywords: foundations, structural engineering, geotechnical engineering, forensic, elevations, relative elevations, floor flatness, foundation distress, statistics, water level, engineering, homebuilder, residence

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  • Dimension Changes and Air Intrusion Characteristics of a Clay

    Author: Arthur S Koenig, PE
    MDI Labs, Inc.
    3130 Mindoro
    San Antonio, TX 78217
    (402) 782-1734