I have a residential project that includes a concrete driveway. The minimum thickness for a slab-on-grade according to the Florida Building Code is 3.50” and most residential slabs are 4” thick. Welded wire fabric (e.g., 6x6-W2.9xW2.9) is often used for crack control. According to ACI 318...
In order for multi-ply wood plates (oriented flat-wise) to behave as a single unit, they must be sufficiently fastened in order to transfer the stress across the shear plane (a shear flow calculation). However, sometimes the amount of fasteners required can be problematic. Is it acceptable to...
I have a wood-framed apartment project where the framer wants to construct the shear walls in segments, and sheath them on the ground before lifting them in place. This introduces vertical seams into the shear wall. I understand that each wall segment will require an end stud and that the...
For wood shear walls sheathed with wood panels, does it matter which direction the panels span over the wall studs, or if adjoining edges are staggered? The SDPWS differentiates between different cases for wood diaphragms, but I cannot find anything for shear walls.
I am looking for the minimum bend radius in the VERTICAL plane of a 1/2" diameter unbonded tendon using a parabolic profile. The available literature discusses the minimum radius of sweeps in the horizontal plane, but I cannot find anything for the vertical plane. The following is what I have...
This question is specifically for structural engineers in Miami-Dade County, Florida:
I have always put the following wind load information on my structural drawings: Design Wind Speed, Risk Category, Exposure Category, the C&C Design Pressures (positive and negative pressures for Zones 1-5)...
We have a single-story “big box” project in Florida that is 480’ x 160’. It was originally an all-steel building, with steel stud exterior walls, and using the Thermal Program (steeltools.org) it shows that an expansion joint is not required (Delta-T = 55 degrees). The project has changed to...
We have been asked to design a large shipping container warehouse where the floor live load is 2,500 psf (specified by the user client). The SOG will be supported on soil that will be improved by stone columns (subgrade modulus = 100 pci after improvement). That design load is off the charts of...
For multi-story wood buildings, I have very often seen the wall studs spaced at 16” o.c. and the trusses spaced at 24” o.c. The trusses bear on a double top plate across the top of the wall studs. This typical configuration will result in every other truss bearing at midspan between the wall...
I have a project with numerous concrete columns that are cast within the plane of concrete masonry walls (a/k/a concrete “tie columns”). The walls and columns are supported only at the floors above and below. The column and walls are 7-5/8” thick and the column widths range from 16”-32”. Does...
We are designing a concrete high-rise building that includes post-tensioned transfer girders supporting multiple levels. Our standard is to design PT beams with a maximum precompression of 350 psi and as Class U (ft <= 7.5sqrt[f'c]). Is this too conservative for a transfer girder? In particular...
This question pertains to the design of lintels in CMU loadbearing walls that support precast hollowcore panels in multi-story buildings (i.e., “block & plank” buildings). It is common knowledge that lintels can be designed for only the loads within the triangular area below the apex so long as...
We are designing several tall cantilevered retaining walls that range from 8’-0” to 16’-0” of retained soil. The walls are subject to a traffic surcharge load as there is a parking lot within several feet of the walls. In the past we used a surcharge of 250 psf and believed this adequately...
Walls constructed of CMU supporting wood-framed roofs is common. The roofs are often sloped, have an overhang, and the roof diaphragms can be large for buildings such as assisted living facilities.
SDPWS states that “diaphragm boundary elements shall be provided [and]… diaphragm chords and...
We are currently designing some long span transfer girders that require a significant amount of 1/2" unbonded tendons. We typically use rectangular tendon bundles that are six tendons wide, and this results in a large number of bundles. Is there a maximum number of tendons per bundle? Is there a...
I am looking for a good pilecap design program and was wondering if anyone had any recommendations. I would prefer a program that uses a FEM solution to determine the pile cap forces, pile reactions, design the reinforcement, etc. Thank you in advance for your advice.
Should the seismic overstrength factor (Omega) be used when determining the foundation design loads? I am specifically referring to the loads as they pertain to the soil-foundation interface, and not the design of the foundation itself.
Should the seismic overstrength factor (Omega) be used when determining the foundation design loads? I am specifically referring to the loads as they pertain to the soil-foundation interface, and not the design of the foundation itself.
ACI 318-05 [10.11.1] allows the use of the reduction factor 0.25Ig for estimating the cracked MOI for concrete flat plates. However, that is not for prestressed flat plates. Assuming a minimum precompression of 125 psi, would not the cracked MOI be something higher than 0.25Ig? If so, what would...
We have a renovation project where we need to reinforce an excisting 8" CMU wall in order to bring it up to Code. The existing wall has minimal vertical reinforcement (if any) and a 1-2 course bond beam across the top. This will be an obvious constructability issue. Has anyone run into this...
