Design Thoughts

X Marks the Brace: Resisting Earthquakes on Capitol Hill's Heritage Buildings

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11th and Pike Steet

11th and Pike Streets Bracing Diagram

Capitol Hill is in one of the most seismically active (i.e. earthquake prone) areas of the world. While not as prone to the frequencies and durations of seismic events of say Japan, the Pacific Northwest can suffer virtually the same magnitude of earthquake damage. Over the years, as understanding of earthquakes has improved, ways of stemming their destructive impacts has increased. Seismologists and geologists have worked to better identify the location, magnitude, frequency, and duration of seismic events. Architects and engineers have spent decades examining post-earthquake structures, studying what has and has not worked to keep buildings from damage and collapse. In the history of construction, however, such knowledge is relatively recent. Also relatively recent is the use of steel, the primary material used to resist seismic forces. Wood frame construction can be designed to resist earthquakes, but if one is retrofitting older buildings, supplementing the existing structure with steel is usually the most practical and effective way to go.

Many of Capitol Hill's buildings were built prior to the time when seismic bracing was required by code. Such buildings, if they have neither gone under a significant renovation nor a change in use (from, say, an automotive showroom to a restaurant, common here on the Hill), have not been required to incorporate bracing. As seismic bracing is an expensive proposition, building bracing without a mandate is uncommon which is why many of our older buildings simply do without. That being said, the observant Hill resident will notice many older buildings do indeed have bracing, a signifier of a change in a building's original use, its expansion, or significant renovation. While the types of forces to be resisted are the same, the magnitude and resolution varies from building to building. This is largely due to the space available for bracing and the size and configuration of the building, leading to a variety of bracing solutions, many of which are visible on Capitol Hill. As each new earthquake provides a test of the current seismic designs, engineers continually refine their approaches, adding yet another layer of variety and richness to this seemingly utilitarian but lifesaving task.

Above is a medium/large heritage building at 11th and Pike Streets. Well cared for -- and recently renovated -- this building's seismic credentials are evident to all who pass through the front door, as they simultaneously pass through a massive, red, chevron brace. And though most robust where the building meets the ground, the brace traces up through at least two floors and two sides. Placing braces along the perimeter of the building is the most efficient deployment; however, circumstance may dictate other locations. In the case of this building, the perimeter walls were available and fit within the over-all renovation concept, so that is where the braces went.

The above diagram parses the visible-from-the-street structural highlights. Typical for this post, the orange represents the seismic bracing, and the blue the gravity structure. To keep things simple, the gravity structure is shown abbreviated (ground floor only) and the seismic indicates only what was visible, although it would be continuous from ground to roof. Eleventh and Pike is a straight forward solution, and very efficient, as it is along the perimeter. Below, one can imagine the strength imparted by the steel frame as one passes between its large, steel tubes.

[caption id="attachment_2326" align="alignnone" width="269" caption="11th and Pike Street Entry"][/caption]

 

[caption id="attachment_2349" align="alignnone" width="280" caption="11th and Pike Street Entry Diagram"][/caption]

Above is a detailed shot of the chevron brace, but even amongst braced frames there are different structural and architectural solutions available. In the above example, a chevron was chosen as it allows for people to pass under it. Had the brace been an 'X', as seen below, it would not have been possible for people to pass through.

The 'X' braces below are at the East Precinct station, on the Pine Street side. Such braces are preferred to the chevron, as the loads are resolved at the intersecting points of the building's gravity structure. Because they tend to be difficult to pass through, 'X' braces are often not used on retrofits, as they tend to block doors and windows. Where this is not an issue, an 'X' can be the most economical and structurally efficient way to go, and here, the braces are duplicated while the size of individual pieces of steel is reduced and both braces work together to resist seismic loading. Of note, police stations, hospitals, and other essential facilities require a higher level of seismic resistance than commercial buildings.

[caption id="attachment_2327" align="alignnone" width="399" caption="East Precinct 'X' Brace"][/caption]

[caption id="attachment_2333" align="alignnone" width="378" caption="East Precinct 'X' Brace Diagram"][/caption]

For retail and restaurant tenants, a brace on a building's facade may not be desirable, even if it is the most effective location as its presence could block visual access to window displays. For clients such as these, architects will collaborate with the structural engineer to place the braces within the body of the building, thus maintaining a cleaner and more accessible facade. This interior brace approach can pose some planning obstacles, but also some interesting opportunities to make the new structural elements a feature of the interior, such as in the Piston and Ring Building, on 12th Avenue, and pictured, below. Similar to 11th and Pike, one passes through a chevron brace to gain access, but access is deeper into the building. Here, the designers met the challenge head on, and used the brace to define the building's entry vestibule, as well as provide an organizing element for the bar at Plum. By placing the brace within, I was able to take the photograph from the sidewalk, unobstructed by a brace. The open facade also allows for the much desired connection of diners to the street life passing by. As in the previous diagrams, orange is the seismic brace, and the blue is the gravity structure (roof trusses in this case).

[caption id="attachment_2329" align="alignnone" width="392" caption="The Piston and Ring Building"][/caption]

[caption id="attachment_2328" align="alignnone" width="394" caption="The Piston and Ring Building Diagram"][/caption]

In addition to supporting a building's main structure (the gravity structure), seismic bracing is also used to prevent non-structural elements from collapse during an earthquake.  Many Capitol Hill buildings are built from un-reinforced masonry, or brick that has no steel reinforcing. In some un-reinforced masonry buildings, these walls may not support gravity loads, but are the primary lateral force resisting system of the building. Unfortunately, these walls are not capable of resisting the rapid back-and-forth motions of major earthquakes, and - without steel - a brittle and can collapse. Due to this lack of reinforcing steel, these walls need the same level of attention against seismic events as does the building's gravity structure. While needed, I equate this level of bracing to a labor of love, Why? Because it can be less expensive to demolish and replace such walls, rather than preserve them. But it is a labor of love worthy of support, if a client has the means, as it preserves another layer of authenticity and heritage of buildings in the neighborhood. Below is an image of the Stumptown 12th Avenue coffee house, and the story it tells is of an owner's determination to preserve as much of the original building as possible, almost regardless of effort.  In addition to the orange and blue in the above diagrams, a new color -- yellow -- has been utilized, this time to highlight the reinforcement of the above mentioned masonry in-fill walls. Note the difference in scale and number of the seismic reinforcement brace of the building structure (orange) with its large tube steel members, to that on the smaller but more numerous steel angles supporting the clay tile walls (yellow). Why the effort? I suspect the owner valued the appearance of the historic clay blocks. While still commonly used in Europe, clay blocks are not commonly seen here and their preservation is a wholly appropriate marker for the age of this building. Imagine the effort and expense needed to maintain the wall. Someone really wanted that to stay. And the pattern of the steel channels, marching along in lock-step making sure the blocks don't come crashing down on your noggin, has its own aesthetic appeal.

[caption id="attachment_2330" align="alignnone" width="420" caption="Stumptown at 12th Avenue"][/caption]

 

[caption id="attachment_2331" align="alignnone" width="421" caption="Stumptown at 12th Diagram"][/caption]

The diagram above reveals the complexity that even such a small space can entail. Note the (orange) steel plates on at the intersection of the columns and the beams, top right, that ties the timber beams to the column. The beams on the left of the image (in blue) appear to be supporting the (yellow) angles that brace the clay blocks and tie the roof to the walls. Here, the gravity structure is not only braced, but also braces -- a nice example of the hierarchy of forces being resisted.

Above are but a few of the examples around us of updated structures on Capitol Hill. As our historic buildings are re-purposed and renovated, we will be treated to ever new solutions to keep our heritage buildings standing in our shaky corner of the world.

 

Pike Street's Nicest Storefront

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Capitol Hill's Pike-Pine corridor is our neighborhood's greatest urban asset and home to some of our best buildings. Odd Fellow's Hall, Agnes Lofts, and the Elysian Brewing building are just a few of the notables. In addition to these larger buildings, there is (at least) one real gem of a building, but easily missed due to its diminutive size and modest appearance. Don't let its size fool you, for this small edifice possesses a singular quality that makes it a giant amongst its larger peers -- an incredibly handsome and well-preserved wood storefront, remarkable both in its delicacy and in that it unpainted wood-- a bold approach given our 8 - 9 months of rather damp weather (paint is tougher than sealer). Fitting cozily between two recent and boldly modern buildings, 1115 E. Pike does not give an inch to its new block-mates. In fact, the two contemporaries framing it heighten the building’s light touch and historic qualities. Former tenants for the building include the Seattle Academy of Arts and Sciences, who used it as their music and activities building, after which it was the Capitol Hill LGBT center. Originally, it was an automotive parts building. It is owned by Anne Michelson, who built the condominiums next door (to the west) and also owns Crescent Down Works (http://www.crescentdownworks.com/), whose offices are inside, and whose fine down garments are made just around the corner at 1423 10th Avenue.

 

Unlike today's storefront window systems, which are almost exclusively made of aluminum (and of much greater heft), those on many of our heritage buildings are made from wood -- most likely Douglas Fir -- our region's most popular species for both rough carpentry (structural use) and fine wood working (furniture). And though I cannot be certain this is Doug-Fir, the storefront does combine both of its favored attributes, for here we have mullions (which are structural) as finely crafted as if they were ornamental woodworking (furniture). This level of handcrafted quality was typical before mass-produced steel and then aluminum storefronts came to the forefront.  Not encrusted with decades of paint or the often multitude of replacements parts, the storefront on 1115 is remarkably intact and in stunning shape, radiating a pleasing golden glow.

Examining the two photos above, one can see that this storefront was built on-site. Despite the (dare I say) machine-like precision of the smaller mullions, the large wood framing members (in blue) have an irregular pattern, indicative of the different trades involved in the storefront's erection (rough framing verses fine woodworking). The photo above shows how the window maker cheated the left transom mullions to be a bit smaller than those in the field to the right, in order to account for the relative imprecision of the larger structural framing. This does not detract from the facade's overall presentation; however, it may actually enhance it by nicely juxtaposing the precision of the window mullions and their clear finish, with that of the large framing members and their dark, ink-blue paint.

This photo reveals how the window itself is framed.  Even though constructed on a par with fine woodworking techniques, its structural role is an important driver in its final form. The part of the mullions furthest from the face of the pane of the glass is the primary structure; the slimmer profiled piece that is closer to the glass is what is holding the glass in place.  Though separate, each contributes to the overall integrity of the assembly. The differing sizes relay this hierarchical deployment, as well as adding nice shadow lines and detail to the whole. This is ultimately, the way it should be, isn't it? -- Beauty derived from a clear and recognizable hierarchy of parts to the whole, with no artificial ingredients needed. A discerning eye may also notice one real advantage our heritage storefronts have over those of today – no insulating glass! Like countless other, older Hill buildings, the glass in this assemble is ¼” thick single pane glass. Today’s high performance systems are an assemblage of two ¼” panes, separated by ½” of air, all contributing to a much more energy efficient product. Modern energy codes are a good and necessary thing, and well worth the efforts, but the aesthetic results are of secondary concern.

Capitol Hill’s Other Bauhaus(es)

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As well as being the name of Capitol Hill’s premier coffee house and a 1980s Goth band, Bauhaus was the name of the modern movement in architecture’s most famous design school. Perhaps the most famous, ever. The only competition for such a superlative may be for the École des Beaux-Arts, the Parisian school that is most (in)famous for its pedagogy of classical architecture, and whose pre-immanence was in fact eclipsed once the Bauhaus came into being in the early 20th Century. The Bauhaus was justly famous as a school for painting, sculptor, dance, graphic design, but it was in the field of architecture that its legacy was — and is — strongest. Modernist icons such as Mies and Gropius both lead and taught at the institution, and both followed with highly successful and influential professional careers after the Bauhaus was disbanded by the Nazis prior to World War II. The design pedagogy taught resulted in some of the 20th Century’s best buildings, including that of the school itself, designed by Gropius and pictured below.  

[caption id="attachment_2113" align="aligncenter" width="550" caption="The Bauhaus (Source: Wikipedia)"]The Bauhaus (Source: Wikipedia)[/caption]

 

It would be hard to underestimate the influence the Bauhaus had on design schools in the United States. After its closing many instructors came here to continue their teaching careers and professional practice. Gropius landed and Harvard, while Mies ended up at the Illinois Institute of Technology in Chicago. Even tiny Black Mountain College (no longer extant) in the mountains of North Carolina landed some Bauhaus alums. The design approach taught was, in its time, at the cutting edge. So cutting edge, in fact, that it was initially a design approach typically found only in larger cities or for larger clients or more prestigious buildings. That was of course bound to change with time, but smaller markets (as Seattle at the time) were longer to embrace the Bauhaus aesthetic, especially for smaller, developer driven buildings. Education also had an influence on the Bauhaus’s dissemination into the U.S., as the Beaux-Arts tradition was what was taught at the vast majority of our universities well into the 1930s, and most likely at the U of Washington as well.

 

[caption id="attachment_2114" align="aligncenter" width="720" caption="303 Harvard Avenue E Corner View"]303 Harvard Avenue E Corner View[/caption]

 

And though perhaps a bit slower to arrive at the modernists dance, Seattle’s Capitol Hill is fortunate to have several Bauhaus/International Style (similar time period and aesthetic) influenced apartments of various sizes, including the mid-sized beauty pictured above, built in 1949. Thirty years elapsed between the construction of the Bauhaus and 303 Harvard Ave E, perhaps enough time for a direct connection to be tenuous; however, the lineage is evident. Cubic massing, concentrated and expansive use of glass (with an emphasis on horizontals juxtaposed by verticals), and something missing form today’s Bauhaus prodigy: the crisp delineation of the depth between the buildings mass (in this case brick) verses its openings.

 

[caption id="attachment_2115" align="aligncenter" width="720" caption="303 Harvard East Elevation"]303 Harvard East Elevation[/caption]

 

Similar to the recently profiled Boylston Court, 303 has the beloved steel window, whose effectiveness as a design element is enhanced by it being framed by the more massive feel of the brick, as well as the little horizontal projections at the window heads and sills. No corner windows here, alas, but the modernist,s next favorite trick — that of the continuous ribbon window — and here deftly used in combination with concrete spandrels on the building’s most significant facade. Nice!

 

[caption id="attachment_2116" align="aligncenter" width="720" caption="303 Harvard Entrance"]303 Harvard Entrance[/caption]

 

Even the addressing numbers have the same proto-super graphic and vertical arrangement as the Bauhaus, this time with an art-deco font. The concrete entry canopy continues the thin lines above the windows in the body of the building, and is at a bit skewed from the mass of the rest of the building. No steel frames here, the window glass is framed directly into the concrete structure, lending it further distinction from the rest of the building. Especially nice is the re-entrant corner and the lone steel post. It would be nice to have a look at the interiors of the units, hopeful that they still may have some great space-age appliances and fixtures.

There are at least several other buildings of this ilk on the Hill, three of which I documented in this pamphlet: Capitol Hill Building Analysis . Each one unique, and each one worthy of providing precedent to future design projects on the Hill — all to better balance the prevalent and suffocating post-modern pastiche that is all too often referenced in the majority of our current development.

Boylston Court

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Courtyard housing is one of the oldest types of housing — whether for individual or multiple families — and dates back to at least ancient Greek times. It has such a lengthy heritage for several reasons, including interior cross ventilation and increased access to daylight. Outdoors, there is the ability to achieve a well-defined (and defended) space, which can be completely enclosed or open. Capitol Hill has its own assortment of courtyard housing, the majority most likely built before the 1970s with the Anhalts, dating to the 1920s, as the most famous example. As to the reasons for courtyards falling out of fashion I can only speculate, but maximizing return on investment must be one of them, as providing large planted landscapes not only lessens the number of units per parcel but also increases operational costs. Whatever the reasons, it is unfortunate fewer of them are being built.  

[caption id="attachment_2102" align="aligncenter" width="720" caption="Boylston Court view of Courtyard from Street"]Boylston Court view of Courtyard from Street[/caption]

 

I have a couple of favorite courtyard housing projects on the Hill, including Boylston Court, a nicely complex project just west of Seattle Central Community College, and the subject of this posting. Boylston Court has several noteworthy qualities, including a lushly planted and well maintained landscape, a south facing courtyard, and – my favorite aspect — an astonishing variety of design and detail in a compact footprint. Taken individually, the parts of Boylston Court are nothing outstanding; rather, it is in their successful assemblage that an exemplary building is found.

 

[caption id="attachment_2103" align="aligncenter" width="720" caption="Boylston Court view of Garages Along Olive"]Boylston Court view of Garages Along Olive[/caption]

 

Most likely built in the 1950s, it has many elements of that era. including roman brick and steel framed windows. I know I am not alone when I write that I am a sucker for steel-framed corner widows. And who wouldn’t be? They occur in several locations at Boylston Court, at both prominent, and well, less prominent, locations (such as this one at the above garage). But ooh, what beauties they are, regardless of location. It is a shame that steel windows today are (incredibly) expensive, making them prohibitive for most projects — a reason for us to treasure and preserve the few remaining ones we have. Other details include the most minimal of handrails (as seen  in the above photo) — similar to the steel windows there is nothing there but the minimum needed for support. Too bad such delicacy  is not allowed by code anymore . . .

 

[caption id="attachment_2104" align="aligncenter" width="730" caption="Boylston Court Southwest Corner of Courtyard at Olive"]Boylston Court Southwest Corner of Courtyard at Olive[/caption]

 

Opposite the courtyard from the above garage photo is another beloved steel-framed corner window, this time with the roof seemingly floating above it. I pray the owners never swap them out for vinyl windows (it does happen). Note how the foreground gives a hint of the courtyard landscape contained beyond.

 

[caption id="attachment_2105" align="aligncenter" width="720" caption="Boylston Court view of Eastern Building from Olive"]Boylston Court view of Eastern Building from Olive[/caption]

 

Above is an alternate view of the garage facade in the second image. Just beyond Boylston Court is an even older apartment building (in blue). Compared to the box that is its neighbor (and mind you, I do fancy boxes) Boyslton Court’s facade and massing falls with the grade. This not only creates a better pedestrian environment (garage doors not withstanding), but also creates a break in the mass of the building at both the roofline and the plane of the facade. Here is a break down in massing (that Holy Grail of design review boards) that is actually understandable and ties back to something tangible. What a refreshing departure from the current modulation craze that seems to have neither rhyme nor reason, other than a designer’s whimsy.

 

[caption id="attachment_2106" align="aligncenter" width="720" caption="Garages and Decks along Boylston Avenue"]Garages and Decks along Boylston Avenue[/caption]

[caption id="attachment_2107" align="aligncenter" width="720" caption="Facade Along Boylston with Varandah Above"]Facade Along Boylston with Varandah Above[/caption]

 

The other street elevation of Boylston Court occurs, appropriately enough, along Boylston Avenue, where the designer created one of the better apartment facades on Capitol Hill although it is (again) dominated by garage doors for a section of its length. Despite this apparent handicap (or because of it?), over the garages there is a nice and spacious verandah on the level above the garage, whose size makes it appear to actually be quite usable. Being this close to the street a nice venue is offered for the residents and passing public to informally engage with one another (or not). Here, the garages are effectively used as a base, an intermediary that helps to maintain protocols. The garages also provide modulation (that again is understandable) to the verandahs, and order the various levels of transparency of the facade as it transitions from brick to metal railing and back to brick. Classic.

 

[caption id="attachment_2108" align="aligncenter" width="720" caption="Boylston Court End Unit with Private Entry"]Boylston Court End Unit with Private Entry[/caption]

 

Further north along Boylston is still another expression, this time more of a townhouse or even a single family home. Making a return appearance is the delicate guardrail from along Olive and the much-loved corner window. This unit even gets a bit of a front yard and entry porch, in place of a verandah, as well as its own set of stairs. Despite this entry being the fourth (fifth?) design treatment of the street frontage of the modestly sized project, the complex’s over-all architectural unity remains in tact. This is an extremely delicate balance to maintain, especially with so little street frontage. To have all of these parts flow cohesively is not something to take for granted, as each section can simultaneously stand on its own merit while still contributing to the greater whole; however, it is not just the buildings that play a role. The landscape’s design is equally important, be it the built landscape of the verandahs, the micro, intimate front yard noted above, or the the courtyard, pictured below.

 

[caption id="attachment_2109" align="aligncenter" width="720" caption="Boylston Court Inner Courtyards"]Boylston Court Inner Courtyards[/caption]

 

Instead of digging a large hole, and filling it with building (a typical approach), the designers of Boylston Court approached the site differently, leading to the above-mentioned qualities.  Where this approach really bears fruit is in the courtyards. In addition to the large, central courtyard depicted above, there are two alley-sized-courtyards that wind their way up the site, to the east and then north, creating a splendid terracing and layering of space effectively creating shared landscapes that are at the same time intimate. A well resolved dichotomy.

 

[caption id="attachment_2110" align="aligncenter" width="720" caption="Courtyard Facade with Wood Siding"]Courtyard Facade with Wood Siding[/caption]

 

Above, one sees the only significant break in the otherwise uniform palette of roman brick — rough sawn cedar siding (a fuller extent can be seen the first photo); curious, that this change is somewhat buried in the courtyard, and not on the street, where it would be more ‘expressive’. Or is it? I like to think it yet another example of the designer’s sophisticated approach. Whisper, don’t scream. Also, the wood siding is a softer material than the brick, and in the designer’s eye more apropos to be within the softer courtyard, the softer landscape.

Boylston Court is a great building in our neighborhood, and a great example of how a context driven design (be that the site or the content of the building’s program) can provide a wealth of valuable clues about which to design, and lead to a building that not only fits well into its context, but enhances and creates its own. It is also a superb example of courtyard housing, and a building typology I would like to see more of on the Hill (albeit, at a greater density).