Simpson Strong-Tie Structural Engineering Blog -

The Legacy of Loma Prieta

Every year on October 17, we take a moment to reflect on the 1989 Loma Prieta earthquake. The 6.9-magnitude earthquake was one of the most powerful and costly quakes to shake the San Francisco Bay area since the 7.9-magnitude earthquake of 1906. The quake caused an estimated $6 billion in damage and, tragically, resulted in 63 deaths and 3,757 injuries.

Many of those casualties were due to failing infrastructure when sections of the Nimitz Freeway collapsed.

Simpson Strong-Tie was founded in Oakland, California — practically in the heart of the Bay Area. Earthquakes were never far from the minds of our founders. It’s why even before Loma Prieta our mission was to provide solutions that help people design and build safer, stronger structures. However, it’s safe to say the earthquake not only reinvigorated our mission but inspired countless structural engineers who would go on to define the next 30 years of Simpson Strong-Tie research and development into community resilience.

Providing Performance Data for Shallowly Embedded Anchors

In the last few years, Simpson Strong-Tie has heard from a number of structural engineers expressing frustration with the lack of performance data for shallowly embedded, post-installed anchors (shallow anchors). Engineers of Record (EOR) have identified a common application for shallow anchors as those related to attachment of sill plates for structural and nonstructural wall-to-podium slab connections. One dilemma faced by the EORs originates in their desire to prevent damage to concrete podium slab reinforcement, especially where reinforcement is located close to the slab’s top surface to resist negative bending moments. EORs further indicate that shallow anchors are frequently needed for the following attachments: hanging MEP fixtures; attaching nonstructural components associated with tenant improvements; and anchoring light equipment.

Three Ways Anchor Designer™ v3.0 Simplifies Design

Since the introduction of strength design for post-installed anchors in IBC 2000, determining the designed capacity of anchors has become increasingly complex. Dozens of variables, such as geometry, concrete conditions, and the specific properties of different anchor types, make a quick, straightforward comparison of design options almost impossible. Leaving behind printed tables and digital spreadsheets, many manufacturers now offer software to simplify anchor design and provide design feedback in real time. Simpson Strong-Tie offers Anchor Designer software to specifiers as a free, intuitive design tool that streamlines the anchor design process.

A Day in the Life of a Simpson Strong-Tie Structural Engineering Intern

As I look back on the past year and a half and think about all the madness surrounding Covid-19, I can’t help but feel as if I’m emerging from some strange cosmic time warp. The time that has passed since the early days of the pandemic feels so slow in the moment, yet, when I think about all that has happened in my life during this period, the time has passed by surprisingly quickly. Continue Reading

RTUD and ATUD Now UL Listed As a Through-Penetration Firestop System

Whether you’re designing and building a one- or two-story single-family residence, or doing the same for a multifamily, mid-rise wood-frame structure, fire and smoke protection features must be considered, and in most cases are required. When a fire starts, time is of the essence and the longer the flame and gases can be contained and the spread of the fire to adjacent spaces is kept in check, the greater the chance firefighters and first responders will have to defeat the blaze. Though many building jurisdictions have slightly different requirements and provisions, the three primary modes of fire rating that codes consider are an F-rating (flame), a T-rating (temperature rise), and an L-rating (air or gas leakage). The F and T ratings are gauged on a resistance per hour basis and the L rating is based on a rating of air leakage in cubic feet per minute per square foot of opening, or CFM/sq.ft. These ratings and provisions are in place to help safeguard against the spread of fire and smoke within the immediate structure as well as to contain the spread of fire to other structures.

Questions Answered: Strong-Wall® High-Strength Wood Shearwall Webinar

In this post, we follow up on our July webinar, Innovations in Strength and Versatility: Overview of the Strong-Wall® High-Strength Wood Shearwall, by answering some of the interesting questions raised by attendees. Continue Reading

Project Profile: Reinforcing Concrete Joists to Increase Load Rating

We’re excited to share another fiber-reinforced polymer (FRP) project that required both flexural and shear strengthening (photo below) of reinforced concrete joists to enable the slab floors to carry more live load. The structure is in Southern California, and appears to have been built in the 1950s or 1960s when pan joist construction was common. The EOR for this project, Structural Focus, is an experienced structural engineering firm known for seismic retrofit solutions. The FRP applicator was FD Thomas Structural Specialties, a contractor with decades of FRP installation experience.

Wall-Bracing Alternatives to Help Designers and Builders Navigate the Lumber Shortage

As lumberyards continue to recover from pandemic-related supply issues, there’s been an ever-increasing shortage of building materials, creating many challenges for building contractors. These shortages have impacted availability of wood structural panel sheathing and, as a result, our field engineers and sales team have received many questions about potential alternative solutions to meet the wall bracing provisions within the International Residential Code (IRC). Simpson Strong-Tie Branch Engineer Silvia Dyer has researched these provisions and compiled this useful information for our team. At Simpson Strong-Tie, customer service is one of our top priorities. Our engineering team is always available to discuss your wall bracing situations and to help you investigate unique wall bracing solutions. Read Silvia’s research and suggestions below.

Case Study: RPS solutions renew popular event structures after Hurricane Harvey damage

Background — Beach pavilions required repair both for column decay and for extensive hurricane damage.

The two pavilions at Rockport Beach Park in Rockport, Texas, have been serving as popular rentals for large weddings, family anniversaries and other events for more than 30 years. The pavilions are elevated approximately 20’above the beach on concrete slabs and columns. Other structural features include CMU and wood roofs.

Project Profile: Special Moment Frame Dropped-Beam Solution Saves Day(light) by Preserving Window Openings

Simpson Strong-Tie recently had the opportunity to work with MAK Construction to come up with a rather unique solution for a residential project in Phoenix, Arizona. Our Strong Frame® Moment Frame Selector software was used by the engineer on record, L.R. Nelson Consulting Engineers, LLC, to design this truly “special” special moment frame (SMF). The challenge for this particular moment frame design was figuring out how to work around a large garage door opening on the bottom floor without obstructing the window openings on the next floor, because the standard SMF design would cause the beam to cross right through the middle of the windows as they were situated. The solution required dropping the beam below the top of the columns, something seldom seen in moment frame designs. However, our engineering services, in collaboration with L.R. Nelson Consulting Engineers, were able to determine that dropping the beam to the needed level would be quite feasible in this case, and within 24 hours a new design was sent to the EOR and to the contractor for final approvals, which were granted.