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According to Appendix C—Alternative Load and Strength Reduction Factors in ACI 318-11¹ and previous versions, a load combination given by Eq. (C.9-2), U = 0.75(1.4D + 1.7L) + 1.6W, can be used for structures when service-level wind loads are used. Because this appendix was removed from ACI 318-142 and ACI 318-19,³ could these requirements still be used when designing with ACI 318-19?

According to Fig. 1 (Fig. R17.10.5.3 in ACI 318-19¹), grout pad thickness is included when calculating stretch length. Is that correct? If using sleeves, can they be filled with grout? What is the effective depth (h_ef) of an anchor with a sleeve?

The Joint ACI-ASCE Committee 445 published a document titled Report on Torsion in Structural Concrete that contained an in-depth review of historical theory development, design models, and simplified design procedures for the effect of torsion in concrete structures. That document contained three design examples that were relatively simple. An important goal of this ACI Special Publication is to provide more realistic design examples that are usable by design professionals. This paper satisfies that goal by showing a detailed solution to a realistic example that has been encountered on several occasions by one of the authors. Another goal of the ACI Special Publication is to show applications where torsion is combined with flexure and shear. In this example, the torsional effects are combined with biaxial flexure and biaxial shear forces. This example includes a check of the new provisions in ACI 318-19 for bi-axial shear effects.

This paper shows a detailed solution for the design of a reinforced concrete grade beam subjected to torsional effects combined with biaxial shear and biaxial flexure. The grade beam is a portion of a structural screen wall system. A 25 psf (1.20 kPa) strength level wind pressure acts on a 20 ft (6.10 m) tall CMU wall supported by a continuous grade beam. The 21 in (533 mm) wide by 18 in (457 mm) deep grade beam is isolated from an expansive soil and is supported by drilled shafts 21 ft (6.40 m) on center. The wind load and gravity loads induce torsion, biaxial bending moments, and biaxial shear forces in the grade beam. This example shows how to calculate the internal forces in the grade beam at the critical section and design the required longitudinal and shear reinforcement according to the ACI 318-19 code.

The design of the grade beam includes closed stirrups of #4 (Ø 12) bars spaced at 5.5 in (140 mm), five #8 (Ø 25) bars used near the top and bottom faces and one #6 (Ø 16) bar used at mid-height near the side faces.

In order to ensure a continuous and reliable path for the lateral loads caused by earthquake or wind forces, FRP-strengthened masonry walls that are part of the lateral load resisting system of a building require the joint work of the FRP strengthening to resist tensile stresses in the masonry and anchorage to the boundary structural elements (foundations or beams) to transfer the loads. This article presents the results of an investigation on the assessment of anchorage methods and FRP strengthening configurations for unreinforced masonry (URM) walls subjected to in-plane loads. Fourteen masonry walls were constructed for this experimental program. All of the walls were built with hollow clay bricks, typical of URM structures in Colombia and other parts of the world. The specimens for this investigation included slender and squat walls. The dimensions of the slender walls were 1.20 m. [4 ft] long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The dimensions of the squat walls: 2.50 m. [8.2 ft.] long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The walls were strengthened using two configurations: (1) Layout ‘H’ involving horizontal CFRP laminates along on wall side, and vertical CFRP laminates at each wall toe on one side of the wall, and (20 Layout ‘X’ involving diagonal CFRP laminates oriented at approximately 45 degrees on one side of the wall. Four anchor systems were evaluated: (1) System 1 (CFRP anchors embedded in the base beam), (2) System 2 (CFRP bonded to the base beam), (3) System 3 (FRP bonded to grout blocks), and (4) System 4 (FRP wrapped around grout blocks). The walls were tested in two series: (1) Series 1 – Monotonic Loading, and (2) Series 2 – Cyclic Loading. The test results demonstrated that Anchor System 4 was the most effective anchorage system. The walls strengthened with Anchor System 4 failed due to rupture of the CFRP laminates wrapped around the grout block. In general, the largest increases in in-plane capacity, when compared to the control walls, were observed in the slender walls. The walls with the ‘H’ Layout showed more ductility and less degradation of the lateral stiffness than the walls strengthened with the ‘X’ Layout.

Masonry buildings form significant part of the cultural heritage in the world. One of most important aspects for old and historical buildings is the vulnerability to lateral loads such as earthquake and wind loads and the need for appropriate strengthening. Fiber reinforced polymer (FRP) composite materials are developed options for strengthening of masonry buildings. The application of FRP composites as externally bonded reinforcement in repairing and strengthening the masonry walls has becoming more attractive than the traditional methods which are based on steel elements. Their excellent strength-to-weight ratio, easy installation and minimized damage for the existing structure made them the best option for strengthening of listed buildings and structures. In this research, an experimental study has been conducted to show the out-of-plane behavior of FRP strengthened large-scale masonry walls. The wall panels made of clay bricks have been investigated and the effectiveness of different type of FRP elements used for strengthening is analyzed.

Wind-tunnel testing is introduced as a means of providing accurate design loads for the structural frames of buildings in a timely and economic manner, overcoming the inherent limitations of code and analytical procedures. Various types of model tests and their relative advantages are described. The nature of the information that the building’s structural engineer must supply to the wind consultant, and the loading information that can be expected in return, are investigated through examples and explanation.