Author Archives: jonochshorn

New Rand Hall code compliance drawings raise additional safety issues

Without the Code variances that have been granted, Cornell’s Rand Hall Fine Arts Library, as a Type V-B building with A-3 occupancy, would be limited to two stories; as it is, the current proposal (including the anticipated roof-top pavilions) is for a five-story building. The proposal, without the variances, would also greatly exceed the allowable per-floor area permitted by the Code, owing to its attachment, without any fire wall separation, to Milstein and Sibley Halls.

Not only does the current proposal exceed the height limits granted by prior variances, but the variances themselves do not even appear to apply to the current proposal at all, since the prior variances were for a 3- or 4-story library, not a 5-story library. This is a classic bait-and-switch move, entirely unjustified by any fire science rationale.

I have already written extensively about the flawed logic underlying these Code variances and also underlying the Fine Arts Library proposals themselves, so I won’t repeat those arguments.

What I will comment upon are the new (for me) Code analysis drawings supplied by the architects that are now available in the Architecture, Art, and Planning Dean’s Office, based upon which a building permit was granted.

There are at least five serious Code violations that I have noticed in these new drawings:

1. The art gallery will become a fifth story as soon as even temporary pavilions are constructed. As such, these pavilions would not be permitted under the Code, even given the already egregious assumptions made about Code compliance for the proposed 4-story building. Because these pavilions are not shown in the drawings, any such construction will require a new building permit, even if the pavilions are only temporary. The pavilions will not be compliant if the Code is followed, since an A-3 assembly space (art gallery with pavilions) is not permitted above the third floor of a sprinklered Type II-B building, and certainly not on the fifth floor.

2. The entire egress strategy for the building, based on having unenclosed interior exit stairs in the atrium, is flawed, to the extent that it is based on 2015 IBC Section 1023.2, exception 2. This section allows interior exit stairways to forgo construction of otherwise required fire-barrier enclosures if they are within an atrium enclosed per 2015 IBC Section 404.6.

However, 2015 IBC Section 404.6 requires the atrium to be separated from adjacent spaces (not only adjacent “stories” but any adjacent “spaces”) by a 1-hour horizontal assembly (and/or fire barrier). There is an occupied space above the atrium (the roof-top art gallery) and yet a 1-hour fire-rated horizontal assembly is not provided that would separate the atrium from the art gallery above. In fact, there are even roof hatches designed to pop open in the event of fire, between the art gallery and the atrium, a strategy which completely violates both the spirit and letter of this Code requirement. Since the requirements of Section 404.6 are not met, having unenclosed interior exit stairways in the atrium is not permitted (and, of course, the atrium itself is noncompliant).

3. Along those lines, the architect’s Code drawings incorrectly state that the second-floor slab provides a non-required 1-hour horizontal fire barrier as per variance 2015-0432. First, there is no such thing as a horizontal fire barrier (it would be called a horizontal assembly). Second, this 1-hour fire rating is not discretionary, but is absolutely required, in order to separate the first floor occupancy from the atrium above. It does not provide “extra” fire safety beyond Code requirements, as is implied.

4. The atrium is improperly labeled; it is drawn as if it consisted of the entire space within the exterior walls of Rand Hall, above the first floor and excluding the “bump” on the southern side. In fact, the atrium consists only of an “opening connecting two or more stories” and not the stories themselves. Therefore, all the stack floor areas are not part of the atrium itself, but are simply stories, adjacent to the atrium, for which atrium smoke calculations must be made. This means that the justification for the roof-top mezzanine is flawed, since it is based on a calculation that its area is no greater than 1/2 the area of the “atrium” it is in. But the mezzanine as drawn is not “in” the atrium; only the stair to the mezzanine is conceivably in the atrium, while the rest of the mezzanine is directly over the stack floors and the mechanical room serving Milstein Hall. It therefore does not qualify as a mezzanine, but would be considered a fifth story.

5. Glazed openings in Stairway A appear to be too close to glazed openings in the southern wall of Rand Hall (unless this glass has a sufficient fire-rating, which is not indicated in the drawings I have examined). Per 2015 IBC Section 1023.7: “Where nonrated walls or unprotected openings enclose the exterior of the stairway or ramps and the walls or openings are exposed by other parts of the building at an angle of less than 180 degrees, the building exterior walls within 10 feet horizontally of a nonrated wall or unprotected opening shall have a fire-resistive rating of not less than 1 hour. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than 3/4 hour. This construction shall extend vertically from the ground to a point 10 feet above the topmost landing of the stairway or ramp, or to the roof line, whichever is lower.”

[Update Aug 26, 2018: Correction made to the statement in the second paragraph contending that prior Code variances were for a 3-story building. In fact, Cornell’s third, 2016, variance was for a 4-story building, although its logic was entirely flawed. Since the current proposal, purported to be for a 4-story building, is actually for a 5-story building, the argument I am making—that prior variances do not apply to the current proposal—still stands.]

Taxi

Harry Chapin was, briefly in the early 1960s, an architecture student at Cornell University. Thankfully, that career choice short-circuited and, after several other initiatives (including an Academy Award-nominated boxing documentary that he wrote and directed in 1968), he ended up as a rather successful singer-songwriter in the 1970s. I arranged and recorded this version of his hit song from 1972, “Taxi,” at home in Ithaca, NY.

I actually went to see Chapin play a benefit concert at Cornell, when I was an architecture student there, perhaps around 1973 or 1974. He was an excellent performer and it was a memorable concert which, in addition to Taxi, included a song he wrote when he was a student at Cornell, about taking the Greyhound bus back to NYC: “Take the Greyhound/ It’s a dog of a way to get around/ Take the Greyhound/ It’s a dog gone easy way to get you down.” If my memory serves me well, the benefit event also featured Jane Fonda and Tom Hayden.

More of my covers, as well as original songs, can be found here.

New Rand Hall windows invite bird collisions

[Update: Oct. 23, 2018] Latest image showing highly-reflective glass—just installed for the Fine Arts Library project in Rand Hall at Cornell University—inviting bird collisions:

Photo by Jonathan Ochshorn, October 23, 2018

According to the Rand Hall Fine Arts Library’s June 18 to June 29, 2018 construction activity highlights and project update: “A full mock up window has been installed on the northern facade. It can be viewed from the sidewalk on University Avenue.”

Rand Hall’s highly reflective trial window appears as an opening to sky and trees, inviting bird collisions.

Based on the trial window, shown in the image above, it seems likely that these highly-reflective windows will be problematic for birds: the windows appear (to the birds) as openings to trees and sky, thereby inviting collisions. There are better bird-safe glazing techniques that are widely known, for example using patterns on the glass that mimic the multi-pane steel-framed “factory” windows that were recently removed. For more information, see the American Bird Conservancy website.

[Update: July 9, 2018] Here’s another image of the same highly-reflective window.

Another image of Rand Hall’s highly-reflective glazing.

[Updated Oct. 16, 2018: The image below shows how it looked on Oct. 8, 2018, with a few more windows installed.]

View on Oct. 8, 2018 (photo by Jonathan Ochshorn)

Additional writings and blog posts on the Rand Hall Fine Arts Library project are linked here.

What LEED Gold Certification Gets You

I just read an article in the May 2018 ASHRAE JOURNAL about Discover Elementary School in Arlington, Va. designed by VMDO Architects; it is currently the largest zero energy elementary school built in the US. It’s interesting to compare its size, cost, and “sustainable” qualities with Cornell’s LEED gold-certified Milstein Hall, the architecture building designed by OMA and Rem Koolhaas. Both are two-story academic buildings.

  Size (sq. ft.) Cost ($ millions) OFF-SITE Energy USED
Discover 97,000 32.3 None
Milstein 50,000 60+ Lots

So, in a nutshell, Milstein Hall is half the size, twice the cost,* and barely meets minimum ASHRAE energy standards,** while the Arlington school actually returns energy to the grid.

Aerial views of the Discovery Elementary School in Arlington, VA (top) and Milstein Hall at Cornell University (bottom)

*To be clear, the Arlington school is half the cost and twice the size; in other words, its cost per square foot is approximately 25% that of Milstein Hall.

**Cornell’s stated goal (see my video) since 2008 is for new buildings “to use 30% less energy than current energy standards and strive towards 50% less energy.” Milstein Hall’s energy model projects a whopping 2% energy reduction compared to this minimum standard.

Handrail problem in Milstein Hall

Milstein Hall, the architecture facility at Cornell designed by OMA and Rem Koolhaas, has a “growing” handrail problem: the vines intended to cover the exterior egress stairway have penetrated the metal grid on which they’re supported, and have rendered the handrail noncompliant.

Vines intended to cover the exterior egress stair for Milstein Hall have penetrated inside the structure and rendered the handrail noncompliant (photo by J. Ochshorn, May 28, 2018)

Handrails must be continuous; the NYS Building Code has this advice: “Handrail gripping surfaces shall be continuous, without interruption by newel posts or other obstructions.”

You Can Close Your Eyes: New Cover

I recorded James Taylor’s 1971 classic, “You Can Close Your Eyes” and made a quick video using the new Final Cut Pro video editing software that I got with my new iMac.

 

Between writing and recording new songs, I’ve been recording covers that were somehow meaningful to me, in chronological order starting with 1963’s Surfer Girl (Beach Boys). All my music, with links to additional videos, can be found here.

I saw James Taylor at the Capitol Theater in Port Chester during my senior year in high school, in 1970. I had already been playing guitar for about 6 years; seeing him perform solo (just voice and guitar) was unforgettable and I’ve been a fan ever since. “You Can Close Your Eyes” came out the following year and became one of my favorites. Beginning about 20 years after that, I starting singing it as a bedtime lullaby for my children.

I also finally created a video for my prior original song, If I Could Sing Like That.
 

Squints on a Triple at Thumbnail

I hosted yesterday’s “Thumbnail” PechaKucha-style 20×20 event at Cornell, whose theme was “taboo.”

Poster for “Taboo” Thumbnail event held at Cornell on April 13, 2018.

As part of the opening monologue, I performed my 2008 song, “Squints on a Triple.”

Three “sketchers” (students in the department of architecture) documented the event in real time

Information about the song, including lyrics and video, can be found here; or go directly to the 2008 YouTube video to see the famous Scrabble game reenacted.

I’ve also recently compiled many of my original songs, including “Squints on a Triple,” in three “Greatest Hits” albums (Squints can be found in Volume 1).

Thirty-four of my “greatest hits” are now available as downloads or streams on three albums

Stream all the songs on Spotify and other digital platforms. Or purchase (and preview) on CD Baby, Amazon, or iTunes.

Why buildings fall down: E. Sibley Hall version

I took a look at several documents that were emailed to me, at my request, on March 21, 2018: the “Building Envelope and Structural Conditions Assessment” for Sibley Hall at Cornell University (prepared by Ryan-Biggs Associates in May 2009) as well as four pages of structural plans and details for the third-floor renovation of E. Sibley Hall (prepared by Robert Silman Associates in March 2015). It seems to me that the structural analysis and mitigation measures proposed for the E. Sibley roof do not reflect the actual behavior of the roof members and do not explain observed displacements, misalignments, and rotations of columns, attic joists, girders, and roof rafters. I am not a structural engineer, but I think that the discrepancies between the Assessment report and structural analysis, on the one hand, and the observed conditions in E. SIbley Hall, on the other hand, warrant further investigation.

First, there is no mention anywhere, in any of the documents, of second-floor and especially third-floor column misalignment, attic joist displacement and rotation, and girder bowing in E. SIbley Hall. Either the engineers simply missed these important structural conditions in their site investigations, or the misalignments, displacements, rotations, and so on occurred after their reports and drawings were prepared — for example, they might have occurred as a result of construction during the third-floor E. Sibley renovation itself. It is also possible that these conditions occurred, or were exacerbated, as a result of the 2009 excavation for Milstein Hall and the underpinning of E. Sibley foundations, or it is possible that they occurred as a result of some original skylight installation decades ago. It would be important to know whether these structural problems (not mentioned in any of the documents) existed before the E. Sibley renovation and the Milstein Hall excavation took place. I was a student here, spending my entire freshman year on the third floor of E. Sibley Hall in 1970–1971; I don’t recall any column misalignment at that time, but, of course, I may not have noticed. I also can’t find any early photos of the interior of E. Sibley Hall that might allow us to determine when this misalignment happened. The two photos showing the interior of E. Sibley Hall provided in the Assessment report are inconclusive, but perhaps the engineers took other photos (not in their Assessment report) that might show the condition of the columns in 2008.

Second, the Assessment report repeatedly emphasizes and notes an outward movement of the exterior masonry walls in E. Sibley Hall. Such an outward movement does not explain (and in fact appears to contradict) the observed inward movement of the interior wooden columns on the third floor of E. Sibley Hall where the skylight opening occurs. This alleged outward movement of the masonry walls is not visible by casual observation, and no evidence is produced to support the contention that the masonry walls have, in fact, displaced laterally. Nor is it clear, even if there has been some outward movement of the masonry walls, that this movement explains the distress in the roof structure.

Third, there is no analysis in the Assessment report or in Silman’s structural drawings of the actual structural behavior of the wooden roof elements in E. SIbley Hall, behavior that is alleged to have caused this outward “thrust” on the exterior masonry walls. In fact, the behavior of this structure is rather complex, since it contains several internal “hinges,” especially at the intersection of the lower and upper sloping members that create the Mansard form. Such hinge conditions could explain why there may well have been both an outward and an inward thrust on the exterior walls (outward) and the interior columns (inward) respectively — especially when attic joists under the skylights were removed. Silman’s structural drawings do not even represent the lower part of the Mansard structure in their “Existing Attic Framing Configuration” section (Figure 1). There is no way to fully understand the structural behavior of E. Sibley’s roof framing without including these Mansard elements in the sections and in the analysis.

Structural roof section, E. Sibley Hall, Cornell

Figure 1. Existing attic framing section from Silman structural drawings, Drawing No. S-110.

Fourth, this mischaracterization of the behavior of the roof apparently led to the conclusion that the two interior lines of girders above the wooden columns on the third floor of E. Sibley Hall should be connected with cables or rods (in tension) to protect against the alleged outward thrust of the roof elements. These tension cables are clearly useless (they are slack) and, in fact, will do nothing to protect against a mode of failure in which the girders above the two lines of inner columns, already leaning towards each other, move further inward under the roof loads (see Figure 4). Silman’s “Design Intent Narrative” is based entirely on the premise of adding tension rods between the third-floor girders to “resolve horizontal spreading force.” There is no mention of the observed fact that, rather than “spreading,” the third-floor columns, along with the girders they support, are actually leaning inward.

Fifth, there appears to be a much smaller misalignment of several second-floor columns in E. Sibley Hall, but in the opposite direction of the third floor columns. In other words, some of the second-floor columns appear to be leaning outward, while the third-floor columns appear to be leaning inward. This could be the result of some outward spreading of the exterior masonry walls. However, such spreading, to the extent that it has occurred, seems to be relatively insignificant in terms of explaining the behavior of the wooden roof structure. There is no obvious evidence of outward movement of the exterior walls from inside E. Sibley Hall. On the third floor, the top edge of the masonry wall appears perfectly straight, whereas the girders over the interior column lines are remarkably out of alignment (see Figure 2 and Figure 3).

images of Sibley Hall column-girder misalignment

Figure 2. These images show the misalignment of third-floor columns (left) and the bowing of the steel girders that they support (right). Photos by J. Ochshorn, April 2018.

Sixth, these column/girder misalignments appear to happen only where the skylights in E. Sibley Hall occur, presumably because either attic joists were removed, or because the structure was not adequately braced during the renovation of the third floor when the older skylight frame was removed. In other words, my assumption is that these former structural elements (i.e., either the attic joists or skylight mullions in the plane of the roof) allowed the inward-acting tendencies (thrusts) of the north and south mansard sections to counteract each other in compression and thereby provide more than 100 years of equilibrium.

Seventh, Silman’s section notes that the “existing rafters [are] pulling from ridge board.” This observation actually contradicts the premise of their structural design — that the roof structure is thrusting outwards. If that premise were true, one would expect that the rafters would be in compression, pushing against the ridge board, rather than in tension, pulling away from the ridge board. This separation of the rafters from the ridge board is better explained by a rotation of the rafter-attic joist-knee wall (considered as a rigid free-body) over the girder on which it is “balanced” — facilitated by its unstable connection (hinge) to the lower inclined Mansard element. This explanation is much more plausible than the “spreading” explanation, since it is consistent with the observed rotation of these wooden roof elements and with the inward displacement of the supporting girder. I measured the distance from the bottom of the attic joists to the finished floor and found that the attic joists were indeed significantly lower where they connect with the inclined Mansard elements, but only at the locations where the columns were most displaced. As would be expected, these locations of maximum column displacement and maximum attic joist rotation occur toward the middle of the north-south bracing walls, as shown schematically in Figure 3: Attic joist “A” (at the bracing wall or frame) is horizontal, with no apparent rotation, whereas attic joist “B” shows significant rotation, with its northern end 1.5 inches lower than its southern end. This rotation, made possible by the “hinged” connection to the inclined Mansard supports, is easier to visualize by examining the section in Figure 4.

Structural plan, E. Sibley roof

Figure 3. This is an annotated, revised, and schematic version of Silman’s “Attic Floor Existing Framing” plan, showing not only how columns and girders are displaced between the north-south bracing walls, but how the attic joist-rafter elements, considered as rigid free-bodies, have rotated and displaced laterally. Locations of maximum column displacement and maximum attic joist rotation occur toward the middle of the north-south bracing walls: Attic joist “A” (at the bracing wall or frame) is horizontal, with no apparent rotation, whereas attic joist “B” shows significant rotation, with its northern end 1.5 inches lower than its southern end. This rotation, made possible by the “hinged” connection to the inclined Mansard supports, is easier to visualize by examining the section in Figure 4. (Annotations and revisions by J. Ochshorn, April 2018)

Eighth, the inward bowing of the steel girders over the misaligned columns on the third floor of E. SIbley (Figures 2 and 3) indicates that these girders — designed to transfer the gravity loads of the roof structure to the columns — are now also acting as parabolic tension chains, resisting the further inward movement of the columns and attic joists (Figure 3). Clearly, these girders were not intended to act in this manner, and there has been no mention, in either the Assessment report or in Silman’s structural drawings, of this potentially dangerous condition. If these girders fail in tension as a result of the inward-acting lateral forces being applied to them by the rafters and attic joists of the roof structure, it is possible that a total failure of the roof structure could follow. Figure 4 shows the observed and alleged movement of columns and walls in E. Sibley Hall. This movement is consistent with a structural model of the Mansard’s wooden elements that is explicitly unstable (i.e., creating what is called a “mechanism”) because it includes an internal hinge at the top of the inclined Mansard supporting wall, making the structure underconstrained internally. It is possible that the third-floor steel girders, having been transformed into parabolic tension chains, are the only things preventing a structural collapse.

Ninth, if the tension rods were ever tightened to reduce their sag, this would have made the condition even worse.

structural section through E. Sibley Hall, Cornell

Figure 4. This is an annotated, revised, and schematic version of the section through E. Sibley Hall provided in the Assessment Report prepared by Ryan-Biggs Associates in May 2009. The black lines show an idealized condition, with no displacement of columns, walls, or girders; the red lines and tones show the current condition (not to scale), with a small outward displacement of the exterior masonry wall (mentioned in the Assessment report, but not visible to the unaided eye), a large inward displacement of the interior wooden columns and their steel girders, and a substantial rotation and displacement of the wooden attic joists and rafters that are supported by the displaced columns/girders on one side, and by the inclined Mansard structure on the other side; and the blue dotted lines show a possible failure mechanism. The roof structure appears to be unstable in its current configuration. (Annotations and revisions by J. Ochshorn, April 2018)

I want to make it clear that I am not suggesting that the E. Sibley Hall roof structure either is, or is not, in danger of collapse. I am not competent to make such a determination. My concern is that neither the Assessment report nor the Silman structural analysis (1) acknowledges the complex nature of this potentially unstable roof structure, (2) notes the actual displaced, misaligned, and rotated condition of the third-floor structural columns, girders, attic joists, and rafters, (3) discusses the structural geometries and forces that would explain these observed conditions, and (4) proposes a remediation strategy that follows logically from an adequate structural analysis.

I strongly believe that Cornell should immediately engage the services of a consulting engineer — preferably an office that was not involved in producing the Assessment report or the structural drawings for the E. Sibley renovation — in order to assess the conditions in E. Sibley Hall and to make recommendations for remediation.