Snow drift procedures in Canada and the U.S. are compared and evaluated.

Cylinder vs. cube conversion.

Ultra-High-Performance Concrete (UHPC) is a concrete class initially developed in the 1990s. UHPC contains no coarse aggregates. When fibers are used in UHPC, it is called Ultra-High-Performance Fiber Reinforced Concrete (UHPFRC) and offers increased strength and durability. The compressive strength of UHPC may have values exceeding 21,750 psi (Graybeal&Davis, 2008). It has been found by researchers, especially at the Kassel Universität, Germany, that UHPC can be designed to reach compressive strengths up to 36,250 psi. In addition to its high compressive strength, UHPC offers enhancements of high strength concrete (HSC) such as very high tensile strength (over 2175 psi) and flexural strength (over 7250 psi), very high ductility, very high durability to freeze-thaw cycles, chloride penetration, abrasion resistance, and carbonation. These enhanced properties will result in the overall improved performance of structures using this material, thus increasing construction safety, providing longer service life, and lower maintenance costs.

Part 1: Section Analysis (STRUCTURE, April 2023) presented a general framework for flexural analysis of singly reinforced and doubly reinforced beam sections. In this Part 2: Section Design, flexural design of singly reinforced and doubly reinforced beam sections is studied. The focus is on general sections instead of rectangular sections only. Although it may be adequate to design beam sections using a trial-and-error approach based on the section analysis steps outlined in Part 1, the design approach presented in this article determines the minimum required steel area to support a given factored bending moment. 

Numbers in computers can only be represented by a fixed number of digits. The predominant number type in Finite Element Method (FEM) software packages is Double-Precision, which is 8 bytes in size. This gives about 15 digits of accuracy. However, during the solution of FEM equations, numerical difficulties or errors may be encountered in certain modeling scenarios due to truncation and round-off errors. The introduction of the Quad-Precision number type, 16 bytes in size providing about a 34-digit accuracy, can reduce FEM solution errors. The author presents a few examples to illustrate the differences in using Double Precision and Quad Precision numbers.

Engineering projects and building code provisions can often seem like Rorschach tests where two people looking at the same thing can draw sharply different conclusions. This article reviews the two-stage analysis procedure in ASCE 7-16, Minimum Design Loads for Buildings and Other Structures, to consider if the provisions are an innocent inkblot or possibly may be interpreted differently by some.

Use of CBFEM for Validation

Have you ever stopped for a second and thought, “do we ever validate our rigid plate assumption when designing anchorage to concrete?” The answer is simple. There is no analytical method for validation and, because the design codes mandate it, the design engineer abides by it as it is a Building and Safety (Plan check) requirement. This article demonstrates how Component Based Finite Element Modeling (CBFEM) can validate any base plate behavior, rigid or non-rigid. So, regardless of what base plate assumption you make as a design professional, now you can get validation.

The Real Failure Mode

A young researcher studying Buckling Restrained Braces (BRB) once commented that a change made in their design had improved the failure mode such that fatigue of the yielding core no longer controlled the BRB’s performance. Upon investigation, the change had simply created a failure mechanism that developed BEFORE the steel would have fatigued had the change not been made. The fatigue life of the BRB had not changed – the rest of the system simply no longer had the capacity to survive until fatigue limits would have been reached. Thus, what was thought to be a benefit, was not. But the point is an important one.