Grade beam

Abstract: This paper presents the results from a series of centrifuge tests and three-dimensional finite-element (FE) analyses, which examined the benefits of combining a footing with a monopile as a solution for foundations that are subjected to large moment loading, such as those used for towers and wind turbines. The experiments were carried out in silica sand and involved monotonic application of lateral loads at an equivalent prototype height of 26 m above the foundations. Tests were conducted on piled footings, monopiles, and unpiled footings. These experimental results together with the findings from the FE analyses show that the footing interacts positively with the piled foundation and that both the rotational stiffness and capacity of the combined piled footing system are greater than the sum of the individual contributions. Increased capacity arises as the footing causes a significant reduction in moment loading on the pile (hence facilitating the application of larger loads), primarily owing to ...

Abstract: A modular precast construction block system (10) with a wall subsystem (12) and a foundation subsystem (14). The wall subsystem (12) has a number of wall units (16) having cavities (40) and prestressed tension cables (58) cast therein. The wall units (16) are vertically stacked with alignment channels (42) in the top surface (28) of one wall unit (16) receiving the key portion in the bottom surface (30) of the wall unit (16) above, to form walls (26) with vertically aligned cavities (40). Threaded wall bars (24) and extension bars (74) are threaded through the cavities with a wall tensioning assembly (22) applying downward force on the wall units (16) and providing structural strength to the wall. The foundation subsystem (14) includes a variety of precast foundation members including T footing members (126), pier members (128), grade beam members (130), and column members (132). The T footing members (126) and grade beam members (130) include complementary angled pairs for creating angled and "T" joint foundation designs.

Abstract: Experiments and analyses were conducted to address concerns about performance of reinforced concrete connections with shallow, wide beams subjected to lateral earthquake loading and to compare behavior of wide beam connections to that of conventional connections. Two wide beam‐column‐slab connections and one conventional beam‐column‐slab connection were subjected to cycles of reversing lateral displacements up to 5% drift. The conventional beam and wide beam connections exhibited similar overall load‐displacement behavior, with similar beam plastic hinge development. The wide beam connections dissipated almost as much energy as the conventional beam connection and had greater slab participation and less joint and beam shear cracking than the conventional beam connection. Experimentally determined wide beam connection stiffness was closer to the conventional beam connection stiffness than had been predicted. Refined models were developed, with features such as rigid end offsets for wide beam conne...

Abstract: An improved precast concrete beam element, useful as a continuous bearing structural foundation member supporting wall and floor slab loads in soil, has a unique shape and includes a bearing surface for spreading vertical loads into the soil and a wall section having a height sufficient to place the bearing surface at a specified bearing depth in the soil. Optionally, the precast beam element also includes a formed-in notch to serve as a block ledge to facilitate weathertight wall installation. By integrating both the slab form edge and the wall ledge, the beam element eliminates the need for field forming. The beam element is manufactured offsite in a mold capable of changing dimension to cast elements with differing bearing heights and differing wall thicknesses as soil and loading conditions require. Installation of the beam element involves simple suspension of the beam element above an excavated trench such that a gap is formed between the bottom and sides of the trench and the surfaces of the beam element. As the beam element is suspended above the trench, a flowable fill material is poured into the trench to fill the gap. When the flowable fill material hardens, the beam element is locked into place, achieving full bearing and lateral stability.