Now showing 1 - 5 of 5
  • Publication
    Assessment of excavation-induced building damage
    Ground movements during excavation have the potential for major impact on nearby buildings, utilities and streets. Increasingly ground movements are controlled at the source. They are assessed by linking the ground loss at the excavation wall to the volume change and displacements in the soil mass, and then to the lateral strains and angular distortion in structural bays or units, and are related to damage using a damage criterion based on the state of strain at a point. Numerical and physical models of excavation-induced building damage were used to vary parameters and develop procedures for assessing distortion and damage. Examples of building distortion and damage are presented for brick bearing wall structures of the 1800’s and early 1900’s, as well as later frame structures, that illustrate how geometry, era of construction, stiffness, and condition influence building response to ground movement.
    Scopus© Citations 11  6799
  • Publication
    Predicting reinforced concrete frame response to excavation induced settlement
    (American Society of Civil Engineering (ASCE), 2009-11) ; ; ;
    In many tunneling and excavation projects, free-field vertical ground movements have been used to predict subsidence and empirical limits have been employed to evaluate risk. Validity of such approaches given the reality of two-dimensional ground movements and the influence of adjacent applied loads has been largely unknown. This paper employed analytical and large-scale experimental efforts to quantify these issues, in the case of a reinforced concrete frame structure adjacent to an excavation. Nearly half of all soil and building movements occurred prior to installation of the first tie-back, even when conservative practices were applied. Free-field data generated a trough half the size of that recorded near the building frames. Empirically based relative gradient limits generally matched the extent and distribution of the damage. Application of various structural limits also generally reflected global experimental response but did not fully identify local damage distribution. Fully free-field data or failure to include accurate two-dimensional soil displacements under-predicted building response by as much as 50% for low-rise concrete frames without grade beams.
      2562Scopus© Citations 36
  • Publication
    Theoretical solutions for strength-scaled unreinforced masonry for scaled soil-structure experimentation
    Reduced-scale masonry testing offers advantages of lower costs and shorter schedules compared to full-scale testing, but achieving results reflective of full-scale behavior requires development and fulfilment of appropriate scaling relationships. In many model-scale experiments, geometric scaling occurs but kinematic and/or dynamic similitude is not fully satisfied. This paper describes the theoretical basis and evolution of the equations necessary to achieve kinematic similitude for soil-structure testing at one-gravity for unreinforced masonry. Critical considerations relate to preventing the soil from being overloaded. By adopting a standard linear relationship of increased soil stiffness with depth, the controlling principle becomes the application of restricted, scaled loads throughout the entirety of the structure-soil system. As such, material strength and stiffness must be scaled accordingly to respond appropriately under the reduced stress. An example is provided for an adjacent excavation experiment with related empirical verification and computational quantification.
    Scopus© Citations 4  1496
  • Publication
    Examples of building response to excavation and tunneling
    Monitoring of ground movements around tunnels and excavations on the Washington Metro led to development of procedures for assessing ground loss or movements at the boundaries of the excavation or tunnel and the distribution of movements through the soil mass to the ground surface and to adjacent structures (Cording and Hansmire, 1975, O’Rourke and Cording, 1974). As the field investigations progressed in Washington, instrumentation and observations were concentrated on the effect of ground movements on structures. (Boscardin and Cording, 1989). More recently, a research program consisting of numerical and model studies correlated with field observations was conducted to assess the relation of building distortion and damage to excavation-induced ground movements. This paper provides examples of building damage and distortion resulting from excavation or tunneling and evaluates the behavior of the buildings using methods developed in previous studies. The buildings are on shallow foundations in U.S.cities. Most are masonry bearing wall structures built in the 1800s or early 1900s.
      1839
  • Publication
    Manufacturing, assembly, and testing of scaled, historic masonry for one-gravity, pseudo-static, soil-structure experiments
    In many model-scale experiments, geometric scaling is upheld but kinematic and/or dynamic similitude is not because of the difficulty in manufacturing and assembling small models. This paper describes scaling, manufacturing, assembly, and testing of 1/10th scaled historic masonry materials for one-gravity, pseudo-static, soil-structure testing. Prototype selection, manufacturing limitations, constructibility constraints, and testing decisions are presented, alongside details related to model construction. Compressive, tensile, and shear capacities of one-tenth scale prototype values, as well as failure mechanisms, were achieved by adopting traditional brick extrusion and firing methods, in conjunction with modifying mortar products developed for historic restoration. When scaled-masonry structures were subjected to adjacent excavation, damage levels and patterns and levels were consistent with full-scale, field observations.
    Scopus© Citations 28  1382